Hp 6177b Service manual

_0

PER

AT!

N G

AND

S E R V

ICE

MAN

U A L

DC

POWER

SUPPLY

CCB

SERIES

MODEL

6177B

•

HEWLETT

Jl:i

PACKARD

=

~----~

DC

POWER

SUPPLY

CCB

SERIES

MODEL 6177B

OPERATING AND

SERVICE

MANUAL

FOR

SERIALS

9C0191

-

0215*

*For

Serials

Below

9C0191

Refer

to

Appendix A

Manual

Backdating

Changes.

*For

serials

above

9C0215

a

Change

Page

may

be

in-

cluded.

100

Locust

Avenue,

Berkeley

Heights,

New

Jersey

07922

HP

Part

No.

06177-90002

Printed:

August,

1969

i}

MANUAL CHANGES

Model

6177B

DC

Power

Supply

Manual

lOP

Part

No.

06177-90002

Make

all

corrections

in

the

manual

according

to

errata

below,

then

check

the

following

table

for

your

power

wi

supply

serial

number

and

enter

any

listed

change(s)

in

the

manual.

SERIAL

MAKE

Prefix

i

Number

CHANGES

9C

0191 -

0275

1

OB

0276

-

0365

1,2

OB

0338,

0339,

1,2,3

0340,

0343,

0346,

0348,

0354,

0356,

0357,

0364

OJ

0366

-

'Jp

1,2,3

ALL

-

Errata

OJ

0426

-

0470

L 2, 3, 4

OJ

0471-0580

1

thru

5

1149A

0581

-up 1

thru

6

CHANGE

I:

Table

5-4,

Step

I

should

read

as

follows:

Remove

CR25

and

CR26 from

circuit

(open).

Open

the

base

lead

of

Q19B.

Disconnect

the

wire

at

point

B

(white

wire).

Refer

to

Component

Location

Diagram,

Figure

7-2.

CF.ANGE 2:

The

serial

number

prefix

of

the

instrument

has

been

changed

from

"9C"

to

"DB".

In

the

Replaceable

Parts

Table,

make

the

following

changes:

Front

Panel

Binding

Post,

White:

Delete,

HP

Part

No.

1510-0067.

Meter

Bezel:

Change

to

lOP

Part

No.

4040-0414.

Connector,

Test

Point,

Jack,

White:

Add.

HP

Part

No.

1251-2440.

Connector,

Test

Point.

Plug,

VIlhite:

Add.

HP

Part

No.

1251-2441:

In

the

Replaceable

Parts

Table

and

on

schematic

diagram,

make

the

following

changes:

R5:

Change

to

5.49k,

l/8W,

HP

Part

No.

0698-

3382.

Rl0:

Change

to

5.1k,

tw,

HP

Part

No.

0698-3-644.

R9:

Change

to

270n,

tw, HP

Part

No.

0686-2715.

Q3,6:

Change

to

HP

Part

No.

06177-80001.

R33:

Change

to

2.4K,

tw,

lOP

Part

No.

0686-2425.

R51:

Change

to

SIn,

tw,

lOP

Part

No.

0686-5105.

CR11:

Add,

HP

Part

No.

1901-0461.

Disconnect

the

cathode

of

VR13

from

TP18

and

connect

the

cathode

of

CRl1

to

cathode

of

VR13.

Connect

anode

of

CR11

to

TP18.

Table

5-4;

Step

1

should

read

as

follows:

Remove

jumper

Jl,

connected

to

anode

of

CR26

(point

A).

Disconnect

wire

at

point

B.

Refer

to

Component

Location

Diagram,

Figure

7-2.

CHANGE

3:

The

serial

number

prefix

of

the

instrument

has

been

change

from"

OB"

to

"OJ" .

In

the

Replaceable

Parts

Table

and

on

the

schematic

diagram,

make

the

following

changes:

R70:

Change

to

270n,

~W,

HP

Part

No.

0686-2715.

CR25,CR26,CR33:

Change

to

HP

Part

No.

1901-

0642.

R50: Add, lOOn,

l/8W,

HP

Part

No.

0757-0401.

connected

between

+OUT

and

the

junction

of

CR25

anode.

CR26

cathode,

and

Ql9A

base.

"In

the

Replaceable

Parts

Table,

delete

Q25

(HP

Part

No.

1854-0311)

from

the

Milln

P.

C,

Board.

Add

new

Q25

(HP

Part

No.

1854-0250)

to

the

Chassis

Electri-

cal.

The

new

electrical

connections

of

the

new

025

have

not

been

changed

but

the

transistor

is

now

mounted

on

the

rear

Heat

Sink.

A

boron

nitride

in-

sulator

(HP

Part

No.

0340-0411)

has

been

installed

under

Q25

before

mounting

it

On

the

Heat

Sink.

ERRATA:

On

Page

5-14,

in

Part

B

of

Table

5-10,

change

Step

(b)

to

read:

,jOutput

current

remains

low."

On

the

schematic

diagram,

make

the

following

changes:

Change

the

references

the

integrated

cir-

cuits

in

the

guard

supply

and

the

main

error

am-

plifier

to

read:

"Z2

(See

Note

11);

Zl

(See

Note

II)!!

respectively.

Change

the

reference

the

jumpers

in

the

meter

circuit

to

read:

"Note

9.

11

Change

the

positions

of

the

Current

Range

Switch

(S2)

to

read

(from

top):

"500mA,

50mA,

5mA."

Change

the

note

in

the

dotted

box

representing

the

Input

Circuit

Board

in

two

places

on

the

schematic

to

read:

"p/o

Input

P.C.

Board

(06177-60021)."

Change

Note

4

to

read:

"All

components

located

on

main

printed

circuit

board

(06177-60022)

un-

less

otherwise

indicated.

"

In

the

Replaceable

Parts

Table,

make

the

following

changes:

VR6:

Change

rating

to

16.2V,

400mW.

Shoulder

Washer,

insulated:

Add,

qty.

6,

HP

Part

No.

2190-0490.

Bushing

Insulator,

collector

screws,

Q7,

Q29,Q30:

Change

HP

Part

No.

to

0340-0170.

Indian

Bead:

Add, HP

Part

No.

4330-0145.

Used

to

prevent

Ferrite

bead

Ll

from

contacting

c?se

of

transistor

Q2.

P.C.

Board

GUide:

Add,

lOP

Part

No.

0403-0150.

Lampholder

Base,

DSl.

DS2:

Change

to

HP

Part

No.

5040-0305.

Manual

Changes/Model

6177B

Manual

HP

Part

No.

06177-90002

Page

-2-

CF.ANGE 4:

In

the

Replaceable

Parts

Table,

change

C33

to

0.01f'F,

200V, HP

Part

No.

0160-0161.

CHANGE 5:

In

the

Replaceable

Parts

Table

make

the

following

changes:

Q6:

Change

to

HP

Part

No.

1853-0083.

R5:

Change

to

6.2k,

IjBW,

±l

%,

HP

Part

No,

0698-5087.

R14:

Change

to

22k,

tW,

HP

Part

No.

0686-2235.

CHANGE 6:

The

standard

colors

for

this

instrument

are

now

mint

gray

(front

and

rear

panels)

and

olive

gray

:

(for

top.

bottom,

and

side

surfaces).

Option

X95

designates

use

of

the

former

color

scheme

of

light

gray

and

blue

gray.

Option

ASS

designates

use

of

a

light

gray

front

panel

and

olive

gray

for

the

re-

maining

surfaces.

New Part

Numbers

are

shown

below:

I

I DESCRIPTION

I STANDARD

Front

Panel,

Complete

06177-60002

Front

Panel,

Top

Insert

06177-60006

Front

Panel,

Bottom

Insert

06177-60004

Heat

Sink,

Rear

PaDel

5020-8067

Rear

Panel

5000-9461

Cover,

Side

5000-8559

Cover,

Top

5060-8585

Cover

I Bottom

5000-9444

Rack

Kit

(Assy.)

5060-8764

Filler

Panel

(Assy.)

5060-8530

5-1-72

•

HP

PART

NO.

OPTION

A85 OPTION X95 •

<;;

06177-60003

<'

E

Refer

to

(

Manual

Parts

"

List

(-

(

Not

Applicable

Not

Applicable

SECTION

I

GENERAL

INFORMATION

1-1

DESCRIPTION

1-2

This

supply,

is

designed

for

applications

requiring

a

constant

current

source

with

a

high

degree

of

regulation

and

stability

and

very

low

ripple

characteristics.

The

use

of

a

three-posi-

tion

output

RANGE

switch

and

a

lO-tum

output

CURRENT

control

result

in

resolution

down

to

O.5f.,lA.

Special

attention

has

been

given

to

circuit

details

so

that

we

11

regu

1a

ted

perfonnance

is

main-

tained

down

to

very

low

output

currents

-

of

the

order

of

1

t-LA.

1-3

A

special

guard

supply,

within

the

unit,

pro-'-'

vides

a

voltage

which

is

used

to

prevent

internal

leakage

currents

which

would

degrade

the

regula-

tion

characteristics.

Since

the

positive

output

voltage

is

held

equal

to

the

guard

voltage.

it

is

also

used

to

drive

the

front

panel

voltmeter

effec-

tively

isolating

the

voltmeter

from

the

main

supply.

This

prevents

the

usual

output

degradation

associ-

ated

with

connecting

a

voltmeter

across

a

constant

current

supply.

1-4

The

supply

is

completely

transistorized

(all-

silicon)

and

is

suitable

for

either

bench

or

rack

operation.

It

is

of

the

Constant

Current/Voltage

\

Umiting

type

that

will

furnish

full

rated

output

current

at

the

maximum

rated

output

voltage

or

can

be

continuously

adjusted

throughout

the

output

range.

The

front

panel

VOLTAGE

control

is

used

to

establish

the

output

voltage

limit

(ceiling)

when

the

supply

is

used

as

a

constant

current

source.

This

control

is

continuously

variable

throughout

the

entire

voltage

range.

The

front

panel

CURRENT

control

can

be

used

to

establish

the

output

current

limit

(overload

or

shOTt-circuit)

if

the

supply

is

used

as

a

voltage

limited

source.

1-5

A

single

meter

is

used

to

meaSure

either

out-

put

voltage

or

current.

The

dual

selection

is

ac-

complished

by

a METER

switch

on

the

front

panel.

Output

current

can

be

measured

in

one

of

three

ranges

in

accordance

with

the

RANGE

SWitch

set-

ting

on

the

front

panel.

Output

voltage

is

measur-

ed

in

only

one

range.

1-6

The

power

supply

has

both

front

and

rear

ter-

minals.

Either

the

positive

or

negative

output

ter-

minal.may

be

grounded

or

the

power

supply

can

be

operated

floating

at

up

to

a

maximum

of

300

Volts

off

grou'Od

(added

safety

precautions

should

be

1-1

taken

to

protect

the

operator

when

the

supply

is

used

in

this

mode).

1-7

Terminals

at

the

rear

of

the

unit

allow

ac-

cess

to

various

control

points

within

the

unit

to

expand

the

operating

capabilities

of

the

instru-

ment.

A

brief

description

of

these

capabilities

is

given

be

low:

a.

Remote

Programming.

The

power

supply

can

be

programmed

(controlled)

from

a

remote

lo-

cation

by

means

of

an

external

voltage

source

or

resistance.

The

output

current

can

be

rapidly

pro-

grammed

in

the

up

or

down

direction

using

this

technique.

Remote

programming

speed

is

less

than

SOOp.sec

from

zero

to

99%

of

maximum

rated

output

with

an

accuracy

of

1%.

b.

External

Voltage

Monitoring.

The

output

voltage

of

the

supply

can

be

externally

monitored

with

an

accurate

differential

or

digita

1

voltmeter

for

applications

involving

component

testing

or

sorting~

Connecting

the

external

meter

to

the

guard

voltage

prevents

output

performance

degradation

when

this

feature

is

employed.

c.

AC

Modulation

of

Output.

An

external

ac

component

(or

varying

de)

can

be

superimposed

on

the

dc

output

current

of

the

supply.

This

feature

permits

measurement

of

dynamic

impedance.

volt-

age

breakdown.

and

leakage

resistance.

1-8

SPECIFICATIONS

1-9

Detailed

specifications

for

the

power

supply

are

given

in

Table

1-1.

1-10

OPTIONS

1-11

Options

are

factory

modifications

of

a

stan-

dard

instrument

that

are

requested

by

the

customer.

The

following

options

are

available

for

the

instru-

ment

covered

by

this

manual.

Where

necessary.

detailed

coverage

of

the

options

is

included

throughout

't.'1e

manual.

Option

No.

14

28

De

scriPtion

Three

Digit

Graduated

Decadial

Current

Control:

Control

that

re-

places

10-turn

current

control

per-

mitting

resettability

to

within

0.1%.

Rewire

For

230V AC

Input;

Supply

as

normally

shipped

is

wired

for

115Vac

input.

Option

28

consists

of

reconnecting-

the

input

transformer

for

230Vac

operation.

'-12

ACCESSORIES

1-13

The

applicable

accessories

listed

in

the

f01-

lo\ving

chart

may

be

ordered

witt

the

instrument

or

separately

from

your

local

Hewlett-Packard

field

saies

offiCE

(refer

to

list

at

rear

of

manual

for

ad-

cresses).

if

Par.:

No,

5060-0806

5060-0097

DescriDtion

Rack

Kit

for

mounting

one

or

two

units.

(Refer

to

Section

II

for

de-

tails,)

Filler

panel

to

block

unused

half

of

rack

when

mounting

only

one

unit.

1-14 INSTRUMENT IDENTIFICATION

1-15

Hewlett-Packard

instruments

are

identified

1-2

by

a

three-part

serial

number

tag.

The

first

part

is

the

unit

mocie1

nu

mber.

The

second

part

is

the

se-

ria

1

number

prefix,

which

consists

of

a

number-

l.etter

combination

that

denotes

the

date

of

a

Sig-

nificant

design

change.

The

number

designates

the

year,

and

the

letter

A

through

L

designates

the

month,

January

through

December

respectively,

with

1

omitted.

The

third

part

is

the

instrument

serial

number.

1-16

If

the

serial

number

prefix

on

your

unit

does

not

agree

with

the

prefix

on

the

title

page

of

this

manual,

change

sheets

are

included

to

update

the

manual.

Where

applicable.

backdating

information

is

given

in

an

appendix

at

the

rear

of

the

manual.·

1-17

ORDERING

ADDITIONAL

MANUALS

1-18

One

manual

is

shipped

with

each

instrument.

A~ditional

manuals

may

be

purchased

from

your

local

Hewlett-Packard

field

office

(see

list

at

rear

of

this

manual

for

addresses)'

Specify

the

model

number,

serial

number

prefix.

and

@

part

number

provided

on

the

title

page.

•

i

I

!

•

! '

Model

6177B,

Specifications

INPUT:

LOAD TRANSIENT RECOVERY

TIME:

,

115Vac±

10%,

single

phase,

48-63Hz,

0.6

Amp,

Less

than

ZOOjJ.sec

for

output

current

recovery

55

Watts

(nominal).

to

within

1%

of

the

nominal

output

current

fol-

lowing

a

full

load

voltage

change

in

the

output

OUTPUT:

voltage.

0-500mA

@

50

Volts.

METER:

OUTPUT

CURRENT

RANGES:

The

front

panel

meter

can

be

used

as

a

0-3

oo

rnA

,

0-500mA,

0-50mA,

or

O-SmA.

0-30mA,

or

0-3mA

ammeter

or

a

O-120V

voltmeter.

LOAD REGULATION:

OUTPUT

CONTROLS:

Less

than

25pprn

of

output

+

Sppm

of

range

Range

switch

selects

desired

output

current

switch

setting

for

a

full

load

to

no

load

change

range

and

meter/line

switch

controls

input

power

in

output

voltage.

and

selects

meter

range.

Ten-turn

current

and

single-turn

voltage

controls

permit

continuous

LINE REGULATION:

adjustment

over

the

entire

output

span.

Less

than

25ppm

for

any

line

voltage

change

within

the

input

rating.

OUTPUT TERMINALS:

Four

output

posts

are

provided

on

the

front

panel

RIPPLE AND

NOISE:

and

two

output

terminal

strips

are

located

on

the

rear

of

the

chassis.

All

power

supply

output

ter-

Output

Range

Ripple

and

Noise-rms/pk-pk

minals

are

isolated

from

the

chassis

and

either

(rnA)

(de

to

20MHz)

the

positive

or

negative

terminal

maybe

connect'-

ed

to

the

chassis

through

a

separate

ground

ter-

500

40;.cA/250;.cA

minal

located

on

the

front

paneL

50 4;.cA/40;.cA

PROGRAMMING

SPEED:

Less

than

SOO\-lsec

are

required

to

program

from

5 o

.4

;.cA

/ 5

;.cA

zero

and

to

99%

of

the

maximum

rated

output

cur-

rent

0:

each

range

or

between

the

maximum

rated

output

current

of

each

range

to

within

1%

of

zero.

TEMPERATURE RANGES:

Operating:

o

to

5SoC.

Storage:

-40

to

+85

0

C.

REMOTE

PROGRAMMING,

CONSTANT CURRENT:

TEMPERATURE

COEFFICIENT:

Programming

Range

(rnA)

Less

than

75ppm

of

output

plus

Sppm

of

range

Source

500

50

5

switch

setting

per

degree

centigrade.

Resistance

STABILITY:

(Accuracy:

1%

of

Less

than

100ppm

of

output

+

2Sppm

of

range

output

+

0.04%

of

4n/mA

40n/mA

400n/mA

switch

setting

total

drift.

Mea

sured

for

8

hours

range)

after

an

initial

warm-up

time

of

one

hour

at

con-

stant

ambient,

consta

nt

line

volta

ge

t

and

Con-

Voltage

stant

load.

(Accuracy:

0.5%

of

output

+

0.04%

2mV/mA

20mV/mA

200mV/rnA

INTERNAL

IMPEDANCE

AS

A

CONSTANT

of

range)

CURRENT

SOURCE:

~

Output

Range

Output

Impedance

REMOTE

PROGRAMMING,

VOLTAGE

LIMIT:

(rnA)

(R

in

parallel

with

C)*

Remote

programming

of

the

voltage

limit

at

ap-

p'roxirnately

870

ohms

per

Volt

is

made

available

500

R=

3.3

Meg,

C = 0.05fJ.£

at

the

rear

terminals.

50 R = 33

Meg,

C =

O.OO5~f

COOLING:

Convection

cooling

is

employed;

no

moving

parts.

5 R =

330

Meg,

C =

500pf

SIZE:

*The

·formula

Z =

RXe/..JR2

+ Xe2

can

3-7/16"

H x

12-3/8"

D x

7-3/4"

W.

be

used

for

calculations,

up

to

IMHz.

WEIGHT:

10

lbs.

net,

13

lbs.

shipping.

1-3

SECTIOfl'

If

Ir;STALLA

liON

2-1

INITIAL

INSPECTION

2-2

Before

shipment,

this

instrument

was

in-

spectec

and

found

to

be

free

of

mechanical

and

eiectrical

defects.

As

soon

as

the

instrument

is

unpacked,

inspect

for

any

carnage

that

may

have

occurred

in

transit.

Save

all

packing

materials

until

the

inspection

is

completed.

If

damage

is

found,

file

a

claim

for

damage

with

the

shipper.

Hewlett-Packard

Sales

and

Service

Office

should

De

notified.

2-3

MECHANICAL CHECK

2-.s.

This

check

should

confirm

that

there

are

no

broken

knobs

or

connectors,

that

the

cabinet

and

panel

surfaces

are

free

of

dents

anc

scratches,

and

that

the

meter

is

not

scratched

or

cracked.

2-5

ELECTRICAL CHECK

2-6

The

instrument

should

be

checked

against

its

electrical

specifications.

Section

V

includes

an

Hin-cabinet"

performance

check

to

verify

proper

instrument

operation.

2-7

INSTALLATION DATA

2-8

The

instrument

is

shipped

ready

for

bench

operation.

It

is

necessary

only

to

connect,

the

in-

strument

to

a

source

of

power

and

it

is

ready

for

operation.

2-9

LOCATION

2-10

This

instrument

is

air

cooled.

Sufficient

space

should

be

allotted

so

that

a

free

flow

of

coolin~

air

can

reach

the

sides

and

rear

of

the

in-

strument

when

it

is

in

operation.

It

should

be

used

in

an

area

where

the

ambient

temperature

does

not

!=-xceed

50°C.

2-11

OUTLINE DIAGRAM

2-12

Figure

2-1

illustrates

the

outline

shape

and

dimensions

of

the

6177B

and

6181B

supplies.

2-13

RACK

MOUNTING

2-14

This

instrument

may

be

rack

mounted

in

a

standard

19

inch

rack

panel

either

alongside

a

sim-

ilar-unit

or

by

itself.

Figure

2-2

shows

how

both

2-1

Figure

2-1.

Outline

Diagram

types

of

installations

are

accomplished.

2-15

To

mount

one,

or

two

units

side-by-side,

proceed

as

follows:

a.

Place

adaptor

frame

on

bench.

b.

Remove

feet

from

submodular

instruments.

Place

instrument(s)

in

frame.

c.

Place

divider

clamps

between

instruments.

d.

Place

divider

c

lamps

in

position

on

each

end

and

push

the

instrument

combination

into

frame.

e.

Insert

screws

on

either

side

of

frame

and

tighten.

Figure

2-2.

Rack

Mounting

One

and

Two

Units

•

,

2-16

INPUT

POWER

REQUIR"M"II:TS

2-17

This

power

supply

may

be

operated

from

either

2.

nominal

115

Volt

or

230

Volt

4S-63Hz

pow-

er

source.

The

unit,

as

shipped

from

the

factory,

is

wirec.

for

115

Volt

operation.

The

input

power

required

when

operated

irom

a

115

Volt

60Hz

power

sourCE

at

full

load

is

55

Vlatts

and

0.6

Ampere.

2-18

CONNECTIONS

FOn

230

VOLT OPERATION

(Figure

2-3)

.~

I !

ip

b

JI

FI o

P/O

SI

01

TRANSFORMER

PRIMARY

CONNECTIONS

FOR

230V

OPERATION.

Figure

2-3.

Primary

Connections

TI

2-19

Normally,

the

two

primary

windings

of

the

input

transformer

are

connected

in

paranei

for

op-

eration

from

115

Volt

source,

To

convert

the

power

supply

to

operation

from a 230

Volt

source,

the

power

transformer

windings

are

connected

in

series

as

follows:

a.

Unplug

the

line

cord

and

remove

the

bot-

tom

cover

from

the

unit.

2-2

b.

Unsoider

jumper

between

taps

1

and

3

and

taps

2

and

4.

These

taps

are

shown

in

Figure

2-4,

and

are

located

on

the

bottom

of

the

unit.

c.

Solder

jumper

between

taps

2

and

3.

d.

Replace

existing

fuse

with

0.5

Ampere,

230

Volt

fuse.

Replace

cover

and

operate

unit

normally.

2-20

POWER CABLE

2-21

To

protect

operating

personnel,

the

National

Electrical

Manufacturers

Association

(NEMA)

rec-

ommends

that

the

instrument

panel

and

cabinet

be

grounded.

This

instrument

is

equipped

with

a

three

conductor

power

cable.

The

third

conductor

is

the

ground

conductor

and

when

the

cable

is

plugged

into

an

appropriate

receptacle,

the

instru-

ment

is

grounded.

The

offset

on

the

power

cable

three-prong

connector

is

the

ground

connec-

tion.

2-22

To

preserve

the

protection

feature

when

op-

erating

the

instrument

from

a

Mo-contact

outlet,

use

a

three-prong

to

two-prong

adapter

and

con-

nect

the

green

lead

on

the

adapter

to

ground.

2-23

REPACKAGING

FOR

SHIPMENT

2-24

To

insure

safe

shipment

of

the

instrument,

it

is

recommended

that

the

package

designeci

for

the

instrument

be

usee.

The

original

packaging

mate-

erial

is

reusable.

If

it

is

not

available,

contact

your

local

Hewlett-Packard

field

office

to

obtain

the

materials.

This

office

will

also

furnish

the

ad-

dress

of

the

nearest

service

office

to

which

the

in-

strument

can

be

shipped.

Be

sure

to

attach

a

tag

to

the

instrument

which

specifies

the

owner,

model

number,

full

seria

1

number,

and

service

required,

or

a

brief

description

of

the

trouble.

SECTION

III

OP:::RATING

INSTRUCTIONS

61778

DC

CURRENT

SOURCE

HEWlETT<>PACK,o..RD

D-50V

Figure

3-1.

Operating

Controls

and

Indicators

3-1 TURN-ON CHECKOUT

PROCEDURE

3-2

The

following

checkout

procedure

describes

the

use

of

the

front

panel

controls

and

indicators

and

ensures

that

the

meter

and

programming

cir-

cuits

are

operable.

Actual

outpu:

current

should

be

checked

with

an

external

ammeter

before

con-

necting

delicate

loads.

a.

Set

line/meter

switch

(1)

to

VOLTS

and

observe

that

UNE

light

(2)

goes

on.

b.

To

select

voltage

limit,

adjust

VOLTAGE

control

(3)

until

front

panel

meter

(4)

indicates

desired

output

voltage

(no

load

connected).

c.

VOLTAGE

UMIT

lamp

(5)

sho.uld

be

on

with

no

load

connected.

d.

To

select

constant

current

output.

tum-

off"supply

and

short

+

and

-

output

terminals

(front

3-1

or

rear).

e.

Set

switch

(1)

to

AMPS

and

select

de-

sired

output

current

range

with

range

switch

(6).

Adjust

CURRENT

control

(7)

for

desired

output

cur-

rent.

=.

Remove

short

and

connect

load

to

output

termina

Is

(front

or

rear).

3-3

OPERATING

MODES

3-4

The

power

supply

is

designed

so

that

its

mode

of

operation

can

be

selected

by

making

strapping

connections

between

particular

terminals

on

the

terminal

strips

at

the

rear

of

the

power

sup-

ply.

The

terminal

designations

are

stenciled

in

white

on

the

power

supply

above

or

below

their

•

res:Je.:::tive

terminals.

The

operator

can

ground

eit'18:-

termmal

0:-

operate

the

power

supply

up

to

300Vd::

of:

ground

([loating).

If

one

outnut

tenni-

DC.:

if

to

be

grounded,

the

grounc

connection

must

D0

r:vo.cis

a7

the

front

panel

since

the

rear

terminal

str-:;J:::

do

not

contain

a grounc;

terminal.

The

ioad

ma:-

D0

connected.

to

either

ths

iront

or

rear

termi-

nal.::

withou:

degrading

the

performance

of

the

supply

in

any

way.

3-~

The

following

paragraphs

describe

the

pro-

cecures

for

utilizing

the

various

oneratlOnal

capa-

bilitie.5

0:

the

power

supply.

A

more

theoretical

desc:iption

concerning

the

operational

features

of

t~is

sU;Jply

is

contained

in

Application

Note

90,

Powe:-

Supply

Handbook,

availatlle

at

no

charge

Irorr.

your

local

Hewlett-Packarc.

sales

office.

3-6

NORMAL

OPERATING

MODE

3-7

The

power

supply'

is

normally

shipped

with

its

rear

terminal

strapping

connections

arranged

ior

:::::onstant

Current/Voltage

Limiting,

local

pro-

grcr.:rr:in;,

singie

uni:

mooe

of

o.oera-;:.ion.

This

strcpping

pattern

is

illustrated

in

Figure

3-2.

The

opera

to:

merely

selects

c

constant

current

output

usin~

the

front

panel

controls

(local

programming,

no

s:rapping

changes

are

necessary).

Figure

3-2.

Normal

Strapping

Pattern

3-8

CONSTANT CURRZNT

3-9

To

select

a

constant

current

output,

proceed

as

follows:

a.

With

output

terminals

shorted

or

open

(see

NOTE).

adjust

CURRENT

control

for

desired

output

current.

b.

"'Vith

output

terminals

open,

adjust

VOLT-

AGE

control

for

maximum

output

voltage

allowable

(voltage

limit),

as

determinec

by

load

conditions.

If

a

load

change

caUSes

the

voltage

limit

to

be

ex-

3-2

ceeded,

ths

power

s~ppiy

will

automatically

crosS-

over

to

constant

voltage

output

a:

the

preset

volt-

age

limit

ane

the

output

current

will.

drop

propo!"-

tionately.

Vrllen

this

occurs,

the

VOLTJ.;,GE

LHv1IT

lamp

on

the

front

panel

will

light.

In

setting

the

voltage

limi'~,

allowance

must

be

made

fo:-

high

peak

voltages

which

can

cause

unwanted

crossover.

(Refer

to

Paragraph

3-34.1

NOTE

\A,ihen

the

unit

is

operating

in

the

vo

It-

age

limit

mode

(LIMIT

lamp

on)

the

front

pane

1

ammeter

indicates

the

pro-

grammed

output

current

rather

than

the

actuai

output

current.

This

enables

the

operato::

to

set

the

OU:PUI

currer:t

(using

the

iront

panel

CUP",q;::K'I

con-

trol)

without

shorting

t1-:e

output

tenni-

nals.

3-10

CONNECTING

LOAD

3-11

Loads

for

a

constant

current

Source

must

al-

ways

be

connected

in

series

(never

in

pa::allel).

If

the

supply

is

used

as

.a

voltage

limited

source,

the

reverse

is

true

-

the

loads

mus:

be

connected

in

parallel.

For

constant

current

operation,

ex:reme

care

must

be

taken

to

avoid

shunt

paths

external.

to

the

power

supply'.

The

presence

of

shunt

paths

will

tend

to

degrade

the

performance

0:

the

supply.

If

the

icad

is

remotely

located

from

the

supply,

shunt

paths

can

be

avoided

by

using

Shielded

cable.

If

the

supply

is

used

as

a

positive

source

(negative

terminal

grounded)

one

end

of

the

shield

can

be

connectec

to

the

guard

terminal

(designated

GUARD

on

the

fron:

and

terminal

AO

on

the

rear)

and

the

other

end

left

unconnected.

This

effectively

pro-

jects

the

internal

guard

voltage

along

the

shield

affording

absolute

protection

against

leakage.

If

the

supply

is

used

as

a

negative

source

the

above

method

cannot

be

utilized.

However,

the

use

of

a

shie

lded

cable

will

be

sufficient

to

prevent

shunt

leakage

for

most

applications.

-----'CAUTI

0

N-----

Never

connect

the

negative

output

ter-

minal

to

the

GUARD

(terminal

AO

on

the

rear).

This

places

a

high

negative

potential

at

the

input

of

differential

amplifiers

Q18

and

Q19

end

will

result

in

damage

to

these

components.

3-12

OPERATION

OF

SUPPLY BEYOND RATED

OUTPUT

3-13

The

Shaded

area

on

the

front

panel

meter

face

indicates

the

amount

of

output

current

or

voltage

that

is

available

in

excess

of

the

rated

output.

Although

the

supply

can

be

operated

in

this

Shaded

region

without

being

damageci,

it

cannot

be

guar-

anteed

to

meet

all

of

its

p8riormance

specifica-

tions.

However,

if

the

line

voltage

is

maintained

above

11SVac,

the

supply

will

probably

operate

within

its

specifications.

3-14

OPTIONAL OPERATING

MODES

3-15

REMOTE PROGRAMMING, CONSTANT CURRENT

3-16

Either

a

resistance

or

a

voltage

source

can

be

used

to

control

the

constant

current

output

of

the

supply.

The

CURRENT

control

on

the

front

pane

1

is

disabled

when

remote

programming

the

supply.

3-17

Resistance

Proarammino

(Fiaure

3-3).

In

this

mode,

the

output

current

varies

at

a

rate

de-

termined

by

the

remote

resistance

programming

co-

efficient.

This

coefficient

is

different

for

each

output

current

range,

as

shown

in

Table

1-1

of

this

manual.

The

programming

coefficient

is

de-

tennined

by

the

constant

current

programming

cur-

rent

which

is

adjusted

to

500

±S~~

at

the

factory.

If

greater

programming

accuracy

is

required,

it

can

be

aChieved

by

changing

resistor

R35

as

outlined

in

Section

V.

•

+

AO

AI

A2 A3

'< - )

PROGRAMMING

~?'

RESISTOR

...-:

L-

Figure

3-3.

Remote

Resistance

Programming,

Constant

Current

~

3-18

Use

stable,

low

noise,

low

temperature

co-

efficient

programming

resistors

to

maintain

the

power

supplies

temperature

coefficient

and

stabil-

ity

specifications.

A

switch

may

be

used

to

set

discrete

values

of

output

current.

A

rI).ake-before-

break

type

of

switch

should

be

used

s'ince

the

out-

put

current

will

exceed

the

maximum

rating

of

the

power

supply

if

the

switch

contacts

open

during

the

switching

interval.

3-3

-----CAUTION'-----

If

the

programming

terminals

(AD

and

AI)

should

open

at

any

time

in

the

re-

mote

programming

mode,

the

output

current

will

rise

to

a

value

that

may

damage

the

power

supply

and/or

the

load.

A

protection

resistor

(2Kn

Model

6177E

or

5Kn

Model

6181B)

can

be

connected

across

the

program-

ming

terminals

to

avoid

the

possibil-

ity;

however.

note

that

the

addition

of

the

resistor

will

alter

the

linear

pro-

gramming

coefficient

given

in

Table

1-1.

3-19

If

the

negative

output

terminal

of

the

supply

is

grounded,

care

must

be

taken

to

avoid

leakage

current

paths

from

the

programming

source

to

the

negative

output

terminal

(ground).

Shunt

paths

such

as

this.

will

seriously

degrade

the

perform-

ance

of

the

supply,

3-20

Voltaae

Proarammina

(Fioure

3-4).

In

this

mode.

the

output

current

varies

at

a

linear

rate

determined

by

the

voltage

programming

coefficient

given

in

Table

l-L

The

entire

voltage

span

for

the

source

is

apprOXimately

0-1

Volt

(Model

6177B)

or

0-2.

5

Volts

(Model

6181B).

The

programming

voltage

should

never

exceed

1.

2

Volts

(Mode

1

Sl77B)

or

3

Volt.

(Model

6181B).

yo!tages

in

ex-

cess

of

this

will

result

in

excessive

power

dissi-

pation

in

the

instrument

and

possible

damage.

+

AO

A I

A2

A3

'191<;:>1

01

4:tr=

VOLTAGE

~

SOURCE F

+

Figure

3-4.

Remote

Voltage

Programming,

Constant

Current

3-21

The

5DOllA

programming

current.

flowing

into

terminal

Al

from

the

reference

supply

(see

sche-

matic),

imposes

two

restrictions

in

the

voltage

programming

mode.

The

first

restriction

is

that

the

voltage

source

must

be

capable

of

sinking

(absorb-

•

in

g)

this

500~

current

and

the

second

restriction

is

that,

if

the

programming

terminals

are

opened,

the

programming

current

will

cause

the

output

cur-

rent

to

rise

to

an

excessive

level

(refer

to

CAUTION

note

of

Paragraph

3-18),

Protection

resistors,

mentioned

in

the

CAUTION

note,

can

be

emp

leyed

to

limit

the

output

current

to

a

safe

va

lue

under

any

conditions.

3-22

Ii

the

user

finds

that

his

voltage

source

can-

no~

sink

the

SOOpp.

programming

curren,.,

the

pro-

gramming

current

path

to

terminal

Al

can

be

opened

by

removing

resistor

R37

from

the

main

printeo

cir-

cuit

board.

This

does

not

detract

from

the

voltage

programming

perionnance

in

any

way;

but

does

eliminate

the

need

for

sinking

the

programming

cur-

ren:.

Opening

R37

also

obviates

the

need

for

an

open

terrr.inal

protection

resistor.

Opening

the

programming

tenninals

with

no

programming

current

results

in

zero

output

current

instead

of

an

exces-

sive

output

current.

3-23

If

the

negative

output

terminal

of

the

supply

is

grounded,

the

voltage

source

must

be

floating

(ungrounded).

In

addition,

shunt

leakage

paths

from

the

floating

source

to

the

negative

terminal

must

be

avoided.

To

accomplish

this,

the

case

of

the

voltage

source

can

be

connected

to

the

guard

terminal

(AD)

affording

complete

protection

against

leakage.

If

this

methoc.

is

used.

ensure

that

the

case

is

not

grounded

by

any

other

means;

such

as

the

power

line.

3-24

REMOTE PROGRAMMING, VOLTAGE LIMIT

3-25

The

voltage

limit

of

the

supply

can

be

pro-

grammed

with

a

remote

resistance

or

voltage

source

if

required.

Note

that

the

front

panel

VOLTAGE

con-

trol

is

disconnected

by

the

foliowing

procedure

s.

3-26

Resistance

Prooramminc

(Figure

3-5).

The

voltage

limit

of

the

supply

is

determined

by

the

programming

coefficient

-

870.!'.

per

Volt

for

Model

6177B

or

435.n.

per

Volt

for

Model

6IBIE.

The

volt-

age

programming

current

is

1. 15mA

(Model

61778)

or

2.

3mA

(Model

6I8lB)

and

is

factory

adjusted

to

within

20%.

Adjustment

of

the

programming

ac-

curacy

can

be

achieved

by

changing

resistor

R6

as

described

in

Section

V.

3-27

A

switch

can

be

used

in

conjunction

with

various

resistance

values

in

order

to

obtain

dis-

crete

voltages.

The

switch

should

have

make-

before-break

contacts

to

avoid

momentarily

open-

ing

the

programming

terminals

during

the

switch-

ing

interval.

Opening

the

programming·~terminals

(-

and

A6)

causes

the

output

voltage

to

rise

above

normal

and

may

damage

the

load

device.

3-28

Voltaae

Proarammina

(Figure

3-6).

In

this

3-4

..;..

AO

Ai

A2

A3

i01CX19~

PROGRAMMING

-

A4

A5

A6

Figure

3-5.

Remote

Resistance

Programming,

Voltage

Limit

mode,

the

voltage

limit

will

vary

in

a I

to

1

ratio

with

the

programming

voltage

(voltage

source).

Similar

to

voltage

programming

the

output

current,

Paragraph

3-19,

the

voltage

source

used

must

be

capable

of

sinking

the

1. lSmA

(Model

6177B)

or

2. 3mA

(Model

6181B)

programming

Cb1.rrent

flowing

into

terminal

AS.

If

the

users

source

cannot

ab-

sorb

this

current,

the

programming

current

path

can

be

opened

by

disconnecting

the

collector

lead

of

02

(see

schematic).

This

does

not

adversely

affect

the

operation

of

the

supply

in

any

way,

+

AO

AI

A2

A3

101~lsa101

~

VOLTAGE

RL

SOURCE

=#f+

'1

01

1°1

-A4 A5 AS

Figure

3-6.

Remote

Voltage

Programming.

Voltage

Limit

3-29

EXTERNAL

VOLTAGE MONITORING

3-30

If

accurate

indications

of

output

voltage

are

required,

they

can

be

obtained

with

an

external

voltmeter,

?s

shown

in

Figure

3-7.

Notice

that

one

end

of

the

meter

is

connected

to

the

guard

ter-

mina

1

(AO).

This

effective

ly

isolates

the

ffi€ter

from

the

main

power

supply',

preventing

the

per-

formance

ciegradation

that

would

occu~

i:

the

meter

were

connected

directly

across

the

+

anc

-

output

terminals.

VM

101

I

-

A4

A5 AS

Figure

3-7.

External

Voltage

Monitoring

NOTE

The

external

voltmeter

must

not

draw

more

than

2mA

from

the

auxiliary

source

that

provides

the

guard

volt-

age.

A

current

drain

in

excesS

of

2mA

will

serious

ly

impair

the

operation

of

the

power

supply.

3-31

EXTERNAL AC MODULATION

3-32

Figure

3-8

shows

a

method

of

superimposing

an

ac

component

on

top

of

the

adjustable

de

output

current

of

the

supply,

which

is

operating

as

a

con-

stant

current

source.

The

dc

current

level

is

con-

trolled

in

the

normal

fashion

from

the

front

panel

while

the

ac

component

of

the

output

current

is

determined

by

the

modulation

percentage.

The

percentage

of

modulation

is

affected

by

the

ampli-

tude

of

the

external

voltage

input

and

the

value

of

the

series

resistance,

as

follows:

%

Modulation

:;;;;

Esource

(pk-pk)/RX

(in

J:..1.

Using

the

above

for-

mula,

the

user

would

require

an

external

resistance

of

2K.n.

and

a 2

Volts

peak-to-peak"±nput

signal

from

the

external

source

to

modulate

a

de

current

level

of

lOOmA

by

100%.

In

this

case,

the

output

.::urrent

would

swing

between

-200mA

and

zero

Am-

3-5

peres.

The

output

current

should

never

be

allowed

to

swing

beyond

the

rating

of

the

supply

(SOOmA,

p-p,

fo:-

Model

61778

or

2S0mA,

p-p,

for

Model

61818)

or

clipping

of

the

output

and

possible

in-

ternal

damage

will

result.

+

AO

Ai

A2 A3

j

idJ!81!i;i

A4

A5

A6

Figure

3-8.

External

AC

Modulation

3-33

The

coupling

capacitor

(C

e)

should

be

chosen

so

that

its

reactance

is

at

least

ten-times

smaller

than

RX

at

the

frequency

of

interest.

For

input

frequencies

up

to

100Hz

the

output

of

the

supply

can

be

modulated

100%.

Above

100Hz

the

modulation

capability

decreases

linearly

to

approx-

imately

10%

at

1000Hz.

3-34

Notice

that

it

is

possible

to

remotely

program

the

dc

output

current

of

the

supply

in

the

external

modulation

mode

of

operation.

This

can

be

accom-

p

lished

by

removing

the

strap

between

Al

and

A2

and

connecting

the

programming

source

across

these

terminals.

3-35

SPECIAL OPERATING CONSIDERATIONS

3-36

PULSE LOADING

3-37

The

power

supply

will

automatically

cross

over

from

constant

current

to

voltage

limiting

oper-

ation

in

response

to

an

increase

(over

the

preset

limit)

in

the

output

voltage.

Although

the

preset

limit

may

be

set

higher

than

the

average

output

voltage

high

peak

voltages

(as

occur

in

pulse

loading)

may

exceed

the

preset

limit

and

cause

crossover

to

occur.

If

this

crossover

limiting

is

not

desired,

set

the

preset

limit

for

the

peak

re-

quirement

and

not

the

average.

•

..

3-32

REVERSE

VOLTAGE LOADING

3-39

Diode

CR34

is

connected

internally

across

the

supply".

Under

normal

operating

conditions,

the

diode

is

reverse

biased

(anode

connected

to

negative

terminal).

If

a

reverse

voltage

is

applied

to

the

output

terminals

(positive

voltage

applied

to

negative

terminal),

the

diode

will

conciuct,

shunt-

ing

current

across

it.

This

diode

protects

the

series

transistors

and

drivers.

3-40

REVERSE

CURRENT LOADING

3-41

k-.

active

load

connected

to

the

power

supply

3-6

may

actually·

deliver

a

reverse

current

to

the

power

supply

during

c

portion

of

its

operating

cycle.

An

external

source

cannot

be

allowed

to

pump

current

into

the

supply

without

loss

of

regulation.

Diodes

CR35

and

CR36,

connected

in

series

with

the

neg-

ative

output

lead,

protect

internal

components

from

damage

by

blocking

these

reverse

currents.

However,

to

avoid

regulation

degradation,

it

is

necessary

to

preload

the

supply

with

a'

dummy

load

resistor

so

that

the

power

supply

delivers

current

through

the

entire

operating

cycle

of

the

load

de-

vice.

SECTION

IV

PRINCIPLES

OF

OPERATION

"

INPUT

POWER

Xf

MR

I

"'~'

I

L-+6.zv

~

.'"

REFERENCE

+56V

SUPPL\'

.

+5,9V

+

ERROR T

AMPL.

'V

i.

r:::::::::lCONST

A.

"1-------,

~

t:vU"R'>R't~~'

I I

I I CO,",P1R h I

l0

1

®"

~'

H-F

CURREh'T

AMP~

RANGE

I

,.""

'<0

I

~,;;.):_'Q.,

....

!

..,...1

__

'-<)0';

CURRENT

SAMPLING

RESISTORS

I

~-"

-~I

__

~

__________

~

__

~

____

~

__

~~

NOTt·---OENOTES

FEEoeACK

PATH.

Figure

4-1.

Overall

Block

Diagram

4-1 OVERALL

BLOCK

DIAGRAM

DISCUSSION

4-2

The

major

circuits

of

the

supply

are

shovln

in

the

overall

block

diagram,

Figure

4-1.

The

input

ae

line

voltage

passes

through

the

power

transfor-

mer

to

the

filter

(6177B)

or

voltage

doubler

(6181B)

where

it

is

converted

to

raw

(uflsegulated)

de.

This

de

current

is

adjusted

by

the

series

regulator

so

that

a

well-regulated

constant

current

is

fed

to

the

output

terminals.

The

range

of

the

output current

is

selected

by

the

range

SWitch

which

determine~

the

value

of

current

sampling

resistance

to

be

pIa

ced

in

series

with

the

(+)

output

terminal.

4-3

During

normal

(constant

current)

operation,

the

conduction

of

the

series

regulator

is

controlled

by

feedba

ck

signals

originated

by

the

constant

cur-

rent

comparator.

This

circuit

compares

the

voltage

drop

across

the

applicable

current

sampling

resis-

tance

with

the

potential

of

the

guard

supply.

The

voltage

drop

across

the

sampling

resistor(s)

is

pro-

portional

to

the

output

current,

and

the

potential

of

4-1

the

guard

supply

is

proportional

to

the

programmed

outp.lt

current,

as

will

be

explained

in

tI!e

paragraphs.

If

a

difference

exists,

that

is,

if

the

actual

output

current

does

not

equal

the

programmed

output

current,

the

comparator

sends

an

"error"

sig-

nal

to

the

series

regulator,

via

the

error

amplifier

and

driver.

This

error

signal

alters

the

mnduction

of

the

series

regulator

so

that

the

potential

across

the

sampling

resistance

equals

the

guard

voltage.

4-4

The

guard

supply

is

an

independent

constant

voltage

supply

whose

output

is

used

to

voltage

pro-

gram

the

output

current

of

the

unit.

The

guard

sup-

ply

compares

the

output

of

the

guard

with

a

fixed

reference

voltage

and

ensures

that

their

difference

is

equal

to

zero

Volts

(W)'

The

voltage

drop

ac!'"oss

the

CURRENT

control,

R40.

equals

the

out-

put

voltage

of

the

guard

with

respect

to

common.

A

change

in

the

setting

or

R40

momentarily

unbalances

a

differential

amplifier

within

the

guard,

which

causes

the

guard

voltage

to

change

by

an

equal

amount.

This

alteration

ba

lances

the

differential

•

r

t

amplifier.

4-5

The

adjusted

output

of

the

guard

supply

is

then

used

as

the

reference

on

which

the

error

sig-

nals

produced

by

the

constant

current

comparator

are

based.

A

change

in

the

output

of

the

guard

sup-

ply

results

in

a

change

in

the

feedback

signal

pro-

duced

by

the

constant

current

comparator.

This

then

causes

the

output

current

of

the

unit

to

vary

in

pro-

portion

to

the

change

"programmed"

by

the

guard

supply.

4-6

The

output

of

the

guard

supply

is

fed

to

a

copper

guard

which

surrounds

the

positive

output

terminal.

Circuitry,

which

would

cause

shunt

cur-

rent

paths

across

the

output

0:

the

supply.

is

COn-

nected

to

the

guard

rather

than

the

positive

output

terminal.

Since

the

(+)

output

terminal,

with

re-

spect

to

common

\$I'

,

is

held

a:

the

same

potential

as

the

guard

with

respect

to

common,

no

leakage

current

can

flow

between

the

two

points.

Any

leak-

age

current

that

does

flow

within

the

unit

comes

from

the

guard

supply

rather

than

the

positive

out-

put

terminal.

In

this

way

leakage

current,

across

the

output

of

the

supply

is

eliminated

and

exact

load

regulation

is

obtained.

4-7

The

meter

circuit

provides

a

continuous

indi-

cation

of

the

output

current

or

voltage.

Since

it

is

tied

to

the

guard

rather

than

the

output

terminals,

the

operation

of

the

meter

circuit

does

not

create

any

degradation

in

the

output

of

the

supply.

This

connection

also

enables

the

operator

to

program

the

output

current

before

connecting

the

load.

4-8

The

voltage

limit

circuit

continuously

monitors

the

output

voltage.

If

this

voltage

exceeds

the

pre-

set

limit

established

by

the

VOLTAGE

limit

controls,

a

shunt

regulator

in

the

circuit

is

driven

into

con-

duction

thus

limiting

the

output

voltage

by

the

amount

of

its

conduction.

The

constant

current

source

provides

a

constant

current

to

the

VOLTAGE

limit

control,

thus,

ensuring

linear

programming

of

the

voltage

limit

threshold.

4-9

Large

increases

in

output

voltage,

too

fast

for

the

voltage

lim~it

circuit

to

manage,

are

limited

by

the

volta

ge

limit

overshoot

control.

This

circuit

acts

as

soon

as

the

voltage

reaches

the

voltage

limit

threshold.

It

clamps

the

output

voltage

to

about

7

Volts

above

the

voltage

limit

setting

until

the

voltage

limit

circuit

can

respond

to

the

high

voltage

condition.

4-10

The

turn-off

control

prevents

reverse

currents

from

flowing

through

the

series

regulator

and

driver

at

turn-off.

It

accomplishes

this

by

reverse

biasing

the

driver

and

series

regulator

when

the

supply

is

turned

off.

4-11

The

H-F

amplifier

improves

the

high

frequency

4-2

gain

of

the

unit.

This

then

helps

to

improve

the

transient

response

of

the

unit

to

both

changing

load

conditions

and

ac

modulation

(see

Paragraph

3-31),

4-12

The

bleed

circuit

keeps

the

series

regulator

biased

in

its

active

region

even

at

low

output

cur-

rent

settings,

by

providing

a

continuous

path

for

current

flow

through

the

series

regulator.

Keeping

the

series

regulator

biased

in

its

active

region

al-

lows

the

regulator

to

maintain

fine

regulation

of

out-

put

current

even

at

low

output

levels.

4-13

The

reference

circuit

provides

stable

voltages

used

throughout

the

unit

for

reference

and

biaSing

purposes.

4-14

As

shown

in

Figure

4-1,

the

common

point

for

this

supply

is

at

the

inboard

side

of

the

sampling

resistor(s).

This

is

a

significan:

point

because

it

ensures

that

only

the

output

current

will

flow

through

the

sampling

resistance.

All

offset

currents

(such

as

the

meter

current)

are

referenced

to

this

common

point

and

thus,

do

not

flow

through

the

sampling

resistance

and

into

the

load.

Notice

that

this

point

should

not

be

used

as

a

ground

connection.

A

separate

terminal

is

provided

for

this

purpose.

4-15

DETAILED

CIRCUIT ANALYSIS

4-16

REFERENCE SUPPLY

4-17

The

reference

supply

is

a

feedback

constant

voltage

supply

which

provides

stable

voltages

used

throughout

the

unit

for

reference

and

biaSing

pur-

poses.

All

of

the

reference

voltages

are

derived

from

the

raw

de

obtained

from

the

full

wa

ve

bridge

rectifier

(CR5,

CR6, CR7,

and

CRS)

and

filter

ca-

pacitor

C3

and

are

measured

with

respect

to

the

unit's

common

point

W'

The

+6.2,

-16.2,

and

+5.6

voltages

are

developed

across

temperature

compen-

sated

Zener

diodes

VRS,

VR6,

and

VR12

respectively.

The

+5.9

reference

voltage

is

developed

at

the

base

of

Q15

which

is

biased

by

a

voltage

dropping

resis-

tor

R35,

factory

selected

to

obtain

this

voltage.

R34

limits

the

current

through

Zener

diode

VRS

to

obtain

the

optimum

positive

bias

leveL

+11.8

Volts.

4-18

The'

regulating

circuit

consists

of

series

regu-

lator

transistors,

011

and

012,

error

amplifier,

Q13,

and

differential

amplifier

Q14

and

015.

The

base

of

014

is

connected

between

voltage

dividing

resistors

R29

and

R30. Any

changes

in

the

output

voltage

of

the

circuit

are

reflected

on

the

base

of

014.

ampli-

fied,

inverted,

and

fed

to

013.

Q13

amplifies

and

inverts

this

signal

which

is

used

to

drive

the

series

regulating

transistors

more

or

less

in

order

to

main-

tain

the

+11.8

Volt

reference.

and

thus

the

other

reference

voltages,

constant.

4-19

An

additional

voltage

is

provided

at

the

input

of

the

reference

circuit.

This

volta

ge

(+Z4.V

linregu-

late

d)

is

not

controlled

by

the

regulator

circuit

and

is

used

in

less

cit1cal

circuitry

of

the

unit.

4-2C

CONSTANT

CURRENT COMPARATOR

4-21

The

constant

current

comparator

is

6

differen-

tial

amplifier

that

compares

the

drop

across

the

samplinQ

resistor{s)

to

the

guard

potential

and

if

a

difference

exists,

sends

an

error:

signal

proportion-

al

to

this

difference

to

the

series

regulato;,-

via

the

mair'";

error

amplifier.

The

error

signal

alters

the

conduction

of

the

regulator

thus

keeping

the

output

constant

and

at

the

desired

programmed

level.

4-22

The

comparator

consists

0:

a

differential

am-

plifier,

019.

and

a constan".:.

current

source.

021.

Q19

consists

of

two

silicon

transistors

housed

in

a

single

package.

The

transistors

have

matched

char-

acteristics

minimizing

diiierential

voltages

due

to

mismatched

stages.

Moreover.

drift

due

to

thennal

differentials

is

minimal

since

both

transistors

oper-

ate

at

essentially

the

same

temperature.

Potentiom-

eter,

E56

allows

further

balancing

of

the

stage

shoule:

this

be

necessary.

CR25

and

CR26

prevent

excessive

voltage

excursiO!1s

from

over

driving

the

stage.

4-23

The

constant

current

comparator

a

cts

in

con-

junction

witb

the

guard

supply

to

set

and

maintain

the

output

current

at

the

desired

level.

It

continu-

ously

compares

t."'r:te

drop

across

the

sampling

resis-

tance,

which

is

proportional

to

the

output

current,

to

the

potential

of

the

guard

supply,

which

is

equal

to

the

programmed

output current

(as

will

be

ex-

plained,

subsequently).

If

a

difference

exists,

the

comparator

sends

an

error

signal

to

the

series

regu-

lator,

via

the

main

error

amplifier

and

driver,

in

orde:

to

maintain

the

output

current

equal

to

the

curren:

programmed

by

the

guard

supply.

4-24

The

RANGE

SWitch

selects

the

proper

value

of

current

sampling

reSistance.

These

values

of

resis-

tance

maintain

equal

voltage

drops

for

proportional

output

current

in

each

range.

For

instance;

in

the

5181E,

in

the

25mA

range,

the

sampling

resistance

is

100./1,..

creating

a

voltage

drop

of

2.5

Volts

across

the

sampling

reSistors

at

maximum

output.

In

the

250m;;

range,

the

sampling

resistance

is

10

.......

,

again

creating

a

2.5

Volt

drop.

4-25

GUARD SUPPLY

L.;-26

The

guard

supply

is

a

self-contained,

constant

voltage

supply,

which

compares

a

portion

of

the

guard

potential

to

a

fixdd

reference

voltage

and

en-

sures

that

their

difference

is

zero.

4-27

The

guard

supply

consists

of

a

differential

amplifier.

Q18.

error

amplifier

and

series

regulator

22.

The

differential

amplifier

consists

of

two

sili-

con'transistors

housed

in

a

single

package.

The

4-3

transistors

have

matched

characteristics,

minimiz-

ing

differential

voltages

due

to

mismatched

stages.

Moreover,

drift

due

to

thermal

differentials

is

mini-

mal

since

both

transistors

operate

a:

essentially

the

same

temperature.

Q22,

acting

as

a

constant

cur-

rent

source

for

the

differential

amplifier,

is

used

to

bia

s

the

emitters

of

both

transistors.

Potentiometer,

R46.

allows

further

balancing

of

the

differential

amplifier

should

this

be

necessary.

GR1S

and

CR16

form a

limiting

network

whicb

prevents

excessive

voltage

excursions

irom

over

driving

the

stage.

4-28

The

output

of

the

guare

supply

is

fed

to

a

copper

guard

which

surrounds

the

positive

output

te:-minal.

As

previously

mentioned,

this

prevents

leakage

currents

across

the

outpt.:.t

terminals

of

the

supply.

4-29

Stage

Ql8B

is

connected

to

the

common

point

0:

the

unit.

The

base

of

Ql8A

is

connected

to

a

summing

pOint

(Al)

at

the

junction

of

the

program-

ming

resistor.

R40,

and

the

curren":

pullout

resistor,

R3

7.

Instantaneous

changes

in

the

guard

potential

result

in

an

increase

of

decrease

i:'.

the

summing

point

potential

and

thus,

unbalances

the

differential

amplifier.

An

error

signal

is

then

produced

and

fed

to

the

series

regulator

of

the

guard

supply

causing

it

to

conduct

more

or

less

in

accordance

with

the

5umr:1ing

point

change.

This

restores

the

potential

of

the

guard

which

balances

the

differential

amplifier.

4-30

R37,

connected

to

the

+5.9

reference

voltage,

acts

to

provide

a

constant

programming

current

through

potentiometer

R40,

which

ensures

linear

programming

by

R40.

Changing

the

setting

of

the

potentiometer

changes

the

potential

at

A1.

This

creates

a

momentary

imbalance

at

the

input

of

the

differential

amplifier,

which

then

sends

an

error

signal

to

the

regulator

to

alter

the

guard

voltage

and

correct

the

difference.

R36,

connected

in

series

with

R40,

acts

to

make

up

any

difference

which

might

be

created

by

the

tolerance

of

the

potentiom-

eter,

by

providing

en

addi:ional

current

trliout;h

R40.

This

then

ensures

full

range

prog:e:nming

by

the

CDRRENT

control.

4-31

H-F

ERROR

AMPLIFIER

4-32

The

E-F

amplifier

improves

:he

high

frequen-

cy

gain

of

the

unit.

This

then

helps

to

improve

the

transient

response

of

the

U:1it

to

both

changing

ioad

conditions

and

ac

modulation

(see

Paragraph

3-31).

4-33

Ml'.IN ERROR

AMPLIFIER

AND DRIVER

4-34

The

main

error

amplifier

(Zl)

receives

the

feedback

Signal.

amplifies

it

and

feeds

it

to

the

driver

stage.

Q26.

027,

and

028

brm.

the

driving

circuit

for

the

series

regulator.

This

circuit

further

amplifies

the

feedback

signal.

inverts

it

and

the

resultant

signal

is

used

to

bias

the

emitter

of

the

•

r

(

se~ies

regulator

thus

controlling

the

conduction

of

the

regulating

stage.

4-35

If

the

voltage

programmin<;

terminals

we:e

to

open

when

the

output

was

open

circuited,

the

out-

put

voltage

could

go

up

as

high

as

200

Volts.

VR14

anc

VR1S

serve

as

a

protection

against

this

condi-

tiOD.

\!Vhen

the

voltage

reaches

approximately

140-

Volts,

the

Zener

diodes

reach

their

break

doVv"TI

po-

te;;.:ial

anc

clamp

the

output

to

140

Volts.

This

pre-

ven::s

break

down

of

other

elements

which

wruld

no::

be

able

to

withstand

this

very

high

voltage.

V::::'13

operates

in

the

same

capacity

should

the

volt-

a

ge

programming

of

the

guard

supply

fail.

4-36

SERIES REGUIATOR

4-37

The

series

regulator

regulates

the

output

of

ths

supply

by

altering

its

conduction

in

accordance

with

the

feedba

ck

error

signal.

The

circuit

cO::1sists

0:

se:-ies

regulating

transistors.

030

and

Q29.

and

a

base

biaSing

source,

025.

By

altering

its

con-

c.uction

in

accordance

with

the

error

signal

applied

to

it,

the

series

regulator

produces

a

well

regulated

out

puc.

at

the

level

established

by

the

currem

con-

troIs.

4-38

Notice

that

the

series

regulato';"

is

connected

in

a

common

base

configuration.

This

increases

the

output

impedance

of

the

supply

thus

givL"1g

it

the

desired

quality

of

a

constant

current

supply.

A

more

detailed

description

concerning

the

desired

features

of

a

constant

current

supply

is

contained

in

Application

Note

90

available

at

your

local

Hewlett-Packard

field

office.

4-39

TURN-OFF

CONTROL

4-40

The

turn-off

control

circuit

prevents

reverse

currents

from

flowing

through

the

series

regulator

at

turn-off.

It

accomplishes

this

by

sending

a.

turn-

down

signal

to

the

series

regulator

via

the

driver.

4-41

During

normal

operation

of

the

supply.

031

supplies

a

bias

potential

to

the

driver.

At

turn-off,

CR30

becomes

reversed

biased.

031

turns

off

quickly,

due

to

the

discharging

of

capacitor

C34.

This

creates

a

negative

potential

at

the

base

of

026.

turning

off

both

the

driver

and

the

series

reg-

ulator.

4-42

BLEED

CIRCUIT

4-43

The

bleed

cirCuit

provides

a

path

for

20mA

of

current

to

flow

through

the

series

regulator.

This

keeps

the

series

regulator

biased

in

its

active

re-

gion

at

all

times.

The

bleed

current

flows

from

the

+24, Volt

unregulated

reference

through

Q1,

back

up

to

the

collector

of

the

series

regulator,

through

the

.

driver

to

common

W

where

it

returns

to

the

-16.2

reference

voltage

tnrough

VR6.

Notice

that

this

4-4

current

aoes

not

go

through

the

loae

nor

through

the

sampling

resistors.

V,Then

the

supply

is

programmed

for

zero

current.

20mA

are

flowing

through

the

com-

mon

node,

however,

zero

current

is

actually

deli-

vered

to

the

load.

Keeping

the

series

regulator

biased

in

its

active

region

at

all

times

makes

it

possible

to

have

good

load

regulation

even

at

low

output

currents.

4-44

VOLTAGE LIMIT

CIRCUIT

4-45

The

voltage

limit

circuit

acts

to

limit

the

potential

across

the

output

terminals

to

some

preset

lL'11it

established

by

the

VOLTAGE

limit

control.

The

circuit

conSists

of

a

voltage

limit

control,

RBI,

feedback

amplifiers

04,

OS,

and

06,

shunt

regula-

tor

07,

voltage

limit

lamp

DS2,

and

lamp

driver

08.

Unaer

normal

operating

conditions,

07

is

turned

ofL

Vlhen

the

voltage

limit

tb...reshold

is

reached.

a

neg-

ative

feedback

signal

is

sent

to

the

feedback

ampli-

fiers.

The

signal

is

inverted,

amplified

and

fed

to

the

shunt

regulator

and

lamp

driver.

This

signal

causes

:)Oth

transistors

to

conduct.

The

output

voltage

is

limited

by

the

amount

of

conduction

of

07.

Also,

with

08

on,

a

current

path

is

completed

through

08

and

DS2.

thus

DS2

turns

on

warning

the

operator

of

the

voltage

limit

condition.

Notice

that

since

the

voltage

limit

section

of

the

supply

em-

ploys

a

separate

shunt

regulator.

the

main

series

regulator

continues

to

regulate

output

current

even

during

voltage

limit

operation.

4-46

Potentiometer

RBI

permits

adjustment

of

the

base

potential

of

04

with

respect-to

(-)

out,

thus

setting

the

point

at

which

the

voltage

limit

threshold

is

reached.

4-47

Constant

Current

Source.

The

constant

cur-

rent

source,

Q2

and

associated

components,

pro-

Vides

a

constant

programming

current

through

the

VOLTAGE

limit

control,

HB1,

thus

ensuring

linear

programming

of

the

voltage

limit

circuit.

VR2

keeps

the

ba

se

of

02

at

a

constant

voltage

ensuring

a

constant

current

output.

R6

is

selected

at

the

fac-

tory

to

bia

s

the

emitter

of

02

so

that

the

proper

pro-

gramming

current

is

obta

iDed.

4-48

Tum-On

Circuit.

C40

and

R41 form a

long

time

constant

Re

network.

When

the

supply

is

ini-

tially

turned

on.

a

turn-on

Signal

is

fed

to

07

via

Q6.

This

limits

the

output,

thus

preventing

turn-on

overshoot

from

damaging

delicate

loads.

After

the

supply

has

been

on

for

a

short

time,

C40

charges

up,

back

biasing

CR40

and

thus

the

turn-on

circuit

has

no

effect

on

nonnal

operation

of

the

supply.

4-49

VOLTAGE

LIMIT OVERSHOOT CONTROL

4-50

This

fast

acting

circuit

protects

the

load

from

initial

large,

fast

rises

in

output

voltage

that

the

voltage

limit

circuit

would

not

otherwise

be

eble

to

limi~.

As

soon

as

the

voltage

limit

threshold

is

ex-

ceeciec.,

the

voltage

limit

overshoot

control

clamps

the

output

voltage

to

a

few

Volts

above

the

thres-

hole

setting,

until

07

has

a

chance

to

tum

on

to

l1rni:

the

output.

4-Sl

\Vhen

the

voltage

limit

threshold

is

exceeded,

Q3

COD-ciucts

heavily

causing

CR12

to

become

for-

ward

biased

and

VR4

and

VR7

to

reach

their

break-

down

voltages.

This

draws

current

from

the

+5.6-

\/olt

reierence.

Since

the

+5.6

Volt

reference

is

tied

to

comrr:on

through

VR12,

the

above

action

actually

craws

C..1rrent

irom

common

away

from

the

load,

thus

lImiting

the

output

to

the

preset

voltage

limit

set-

tlTIg

plus

about

7

Volts.

4-52

METER

CIRCUIT

4-53

The

meter

circuit

provides

a

continuous

indi-

cation

0:

the

output

current,

in

anyone

of

three

ranges,

or

the

output

voltage.

The

meter

ranges

are

controlled

by

the

same

switch

tha:

controls

the

output

current

ranges.

For

this

reason,

when

the

range

switch

is

moved

to

the

range,

the

output current

changes

to

ten

times

the

original

value,

but

the

needle

on

the

meter

will

not

move.

However.

it

should

be

understood

tna:

the

meter

is

now

reading

ten

times

the

indicated

value.

The

re-

verse

is

true

when

switching

to

the

range.

4-5

4-54

Notice

that

the

ammete:

is

connected

from

common

~

to

guard

and

the

voltmeter

from (-)

out

to

guard.

]:"5

explaIned

previously,

the

(+)

output

terminal

is

kept

at

the

same

potential

as

the

guard.

Th'...ls,

the

ammeter

is

actually

reading

the

voltage

across

the

sampling

resistance

which

is

proportion-

al

to

the

outpu'!:

current,

and

the

voltmete:

reeds

the

actual

output

voltage.

Connecting

the

mete

to

guard

eliminates

any

shunt

current

paths

which

might

be

created

by

the

ITf€ter

CIfcuit.

1:

also

allows

the

operator

to

program

the

output

before

connecting

the

load,

since

the

meter

reads

the

programmeci

out-

put

current.

4-55

ADDITIONAL FEATURES

4-56

Two

diodes

(CR3S

and

CR36)

placed

in

series

with

the

negative

output

terminal,

prevent

reverse

current

from

flowing

into

the

supply

and

possibly

damaging

its

components.

They

also

allow

the

sup-

ply

voltage

limit

to

be

programmed

through

zero

by

offsetting

minor

base

to

emitter

voltage

drops

in

the,

voltage

feedback

loop.

4-57

R80,

connected

across

the

supply,

keeps

the

supply

from

oscillating

with

an

iI1ductive

load

con-

nected.

CR34

prevents

reverse

voltages

from

dam-

aging

the

supply.

•

HP 6177B Service manual

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