Linear Technology DC1850A-A Quick setup guide

1
dc1850aabf
DEMO MANUAL
DC1850A-A/DC1850A-B
Description
LTC4366HTS8-1/LTC4366HTS8-2
Very High Voltage Surge Stopper
Demonstration Circuit 1850A showcases the LT C
®
4366
high voltage surge stopper in a 28V vehicular application.
DC1850A withstands inputs of up to 100VDC and input
transients of up to 250V while maintaining the output at
43.1V. Reverse battery and errant inputs of up to –100VDC
are blocked from reaching the output.
performance summary
DC1850A-A features latchoff behavior after a fault and is
reset by asserting the SHUTDOWN input high for at least
100µs. DC1850A-B features auto-retry 9 seconds after
tripping off in an overvoltage fault condition. The 9 second
delay can be interrupted by pulsing the SHUTDOWN input.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Range
Operating
DC Survival
1ms Transient
Load = 1.5A
18
–100
250
28 41
100
V
V
V
Output Regulation 41 43.1 45.3 V
Surge Timer
Cool-Down Timer
Input = 100V (DC1850A-B) 1.2
5.9
2.8
9
4.9
16
ms
s
Specifications are at TA= 25°C

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dc1850aabf
DEMO MANUAL
DC1850A-A/DC1850A-B
overview
The LTC4366 surge stopper operates in a floating topol-
ogy, permitting the design of circuits capable of operating
at virtually unlimited input voltage. DC1850A has been
designed to protect against ±100VDC and 250V for 1ms,
in 28V vehicle applications. The input start-up range is
18V to 41V, while after start-up the input can fall to ap-
proximately 7V while still passing 1.5A load current.
Careful attention has been paid to the layout to provide at
least 87mil (2.2mm) clearance between input and output,
and input and ground. This wide clearance is capable of
withstanding 100VDC and spikes to 250V without arcing.
The operating ranges are shown in silkscreen on the top
of the board. The bottom shows the U1 part number, top
mark and behavior associated with the –A and –B ver-
sions of DC1850A. This same information is shown on
the schematic.
Three ancillary circuits are located on the bottom of the
board.
Shutdown Level Shifter
Since the LTC4366 operates in a floating topology, it is
necessary to level shift ground-referred shutdown signal-
ling. A simple NPN circuit provides level shifting between
the SHUTDOWN turret and the LTC4366’s SD pin.
Wide Voltage Range Constant Current LED Driver
Making an LED operate at constant brightness over a
wide operating range is made possible by a simple, two-
transistor circuit. Input LED (D6) current is held constant
from 18V to 250V, and emits some light as low as 7V.
Output LED (D5) is biased with a 9.1k resistor (R7, on bot-
tom of board). Its brightness will vary with output voltage.
−100V Reverse Voltage Protection Circuit
Reverse polarity inputs of up to −100V are blocked from
reaching the load by M2, whose associated circuitry is
located on the bottom of the board. This circuit blocks
reverse inputs of up to −250VDC, provided the input is
applied from a cold start. If DC1850A is already on and
operating with a positive input voltage, instantaneous
spikes must not exceed −100V.
SHUTDOWN TURRET
If the SHUTDOWN turret is left open, DC1850A defaults
to the ON state and turns on when an input supply is
connected. Pulling SHUTDOWN to 1.8V or higher causes
the LTC4366 to enter its shutdown state. The circuit
board layout limits the maximum SHUTDOWN voltage to
60VDC, while R2 limits the peak applied transient voltage
capability to 100V.
OPTIONAL COMPONENTS
Tw o optional components, CX and RX are made available
for those who wish to experiment with the frequency
response of the overvoltage regulation loop.
HOW TO OPERATE DC1850A
Operation of DC1850A is straightforward: connect an
input supply of 18V to 41V, and an output load of up to
1.5A. If the SHUTDOWN turret is open circuit the output
will power up. If the input voltage is increased above
≈ 43.1V, the output will limit and shut off after 2.8ms. DC
inputs of up to ±100V may be applied. The basic hookup
is shown in Figure 1.

3
dc1850aabf
DEMO MANUAL
DC1850A-A/DC1850A-B
overview
Figure 1. DC1850A Basic Hookup
18V TO 41V
INPUT
0A TO 1.5A
LOAD

4
dc1850aabf
DEMO MANUAL
DC1850A-A/DC1850A-B
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
1 1 CF CAP., X7R, 1000pF 100V, 10%, 0603 AVX, 06031C102KAT2A
2 2 CT, CG CAP., X7R, 0.01µF 100V, 10%, 0603 AVX, 06031C103KAT2A
3 1 CLOAD CAP., ALUM. 100µF 50V, 20% SUN ELECT, 50CE100LX
4 1 C1 CAP., X7R, 0.47µF 25V, 10%, 0603 AVX, 06033C474KAT2A
5 0 CX (OPT) CAP., X7R, 0.01µF 100V, 10%, 0603
6 1 CSNUB CAP., X7R, 0.01µF 500V, 20%, 1210 AVX, 12107C103MAT2A
7 5 D1, D2, D3, D4, D7 DIODE, SWITCH 300V 400MW SOD123 DIODES INC, BAV3004W-7-F
8 2 D5, D6 LED, GREEN S-GW TYPE SMD PANASONIC, LN1371SGTRP
9 6 E1, E3, E4, E5, E6, E8 TESTPOINT, TURRET, .094" MILL-MAX, 2501-2-00-80-00-00-07-0
10 4 E18, E19, E20, E21 JACK, BANANA KEYSTONE, 575-4
11 2 M1, M2 MOSFET, N-CH 250V 33A D2PAK FAIRCHILD, FDB33N25TM
12 3 Q1, Q2, Q3 TRANSISTOR, GP NPN AMP SOT-23 DIODES INC, MMBT3904-7-F
13 1 Q4 TRANS., AMP NPN GP 300V SOT-223 FAIRCHILD, PZTA42 TR
14 1 RFB1 RES., CHIP, 12.4k, 1%, 0603 NIC, NRC06F1242TRF
15 1 RFB2 RES., CHIP, 422k, 1%, 0603 NIC, NRC06F4223TRF
16 1 RG RES., CHIP, 10, 5%, 0603 NIC, NRC06J100TRF
17 1 RSS RES., CHIP, 34k, 1%, 0603 VISHAY, CRCW060334K0FKEA
18 1 RIN RES., CHIP, 392k, 1%, 1206 VISHAY, CRCW1206392KFKEA
19 4 R1, R2, R3, R5 RES., CHIP, 470k, 5%, 0603 NIC, NRC06J474TRF
20 3 R4, R6, R9 RES., CHIP, 270k, 5%, 1206 NIC, NRC12J274TRF
21 1 R7 RES., CHIP, 9.1k, 5%, 1206 NIC, NRC12J912TRF
22 1 R8 RES., CHIP, 4.7k, 5%, 0603 NIC, NRC06J472TRF
23 1 R10 RES., CHIP, 200, 5%, 0603 NIC, NRC06J201TRF
24 0 RX (OPT) RES., CHIP, 100k, 1%, 0603
25 1 RSNUB RES., CHIP,100Ω, 5%, 1210 NIC, NRCP25J101TRF
26 4 STAND OFF STAND OFF 0.375" KEYSTONE, 8832

5
dc1850aabf
DEMO MANUAL
DC1850A-A/DC1850A-B
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
schematic Diagram
5 5
4 4
3 3
2 2
1 1
D D C C B B A A
OUTPUT
1.5A MAXIMUM
CLAMPED AT 43.1V
18V - 41V
-100V REVERSE VOLTAGE PROTECTION CIRCUIT
WIDE VOLTAGE RANGE
CONSTANT CURRENT LED DRIVER
INPUT RANGE
DC OPERATING DC SURVIVAL
18V - 41V
+/- 100V
OUTPUT CLAMP SURGE TIMER MAXIMUM LOAD
2.8ms 1.5A 43.1V
INPUT
*
ASSY
DC1850A-A LTC4366HTS8-1
U1
DC1850A-B
BEHAVIOR
LATCH OFF
AUTO RETRY
LTFMC LTFMF
PART NUMBER PART MARKING LTC4366HTS8-2
*
+
SHUTDOWN LEVEL SHIFTER
OUTPUT
INPUT
1ms TRANSIENT 250V
100k
OPT
GND
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: [phone] Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
3
Wednesday, June 20, 2012
11
VERY HIGH VOLTAGE SURGE STOPPER
HZ
Mitchell L.
N/A
LTC4366HTS8 FAMILY
DEMO CIRCUIT 1850A
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: [phone] Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
3
Wednesday, June 20, 2012
11
VERY HIGH VOLTAGE SURGE STOPPER
HZ
Mitchell L.
N/A
LTC4366HTS8 FAMILY
DEMO CIRCUIT 1850A
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY
Fax: [phone] Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
3
Wednesday, June 20, 2012
11
VERY HIGH VOLTAGE SURGE STOPPER
HZ
Mitchell L.
N/A
LTC4366HTS8 FAMILY
DEMO CIRCUIT 1850A
REVISION HISTORY DESCRIPTION DATEAPPROVEDECO REV
Mitchell L.PRODUCTION
36-5-12
__
REVISION HISTORY DESCRIPTION DATEAPPROVEDECO REV
Mitchell L.PRODUCTION
36-5-12
__
REVISION HISTORY DESCRIPTION DATEAPPROVEDECO REV
Mitchell L.PRODUCTION
36-5-12
__
CLOAD
100uF
50V
CLOAD
100uF
50V
D1
BAV3004W
D1
BAV3004W
1 2
R4 270kR4 270k
E18E18
E5E5
R7 9.1k R7 9.1k
R3 470k R3 470k
Q1
MMBT3904
Q1
MMBT3904
1
32
E1
SHUTDOWN
E1
SHUTDOWN
E21E21
E8
GND
E8
GND
CT
10nF 100V
CT
10nF 100V
RFB1 12.4k RFB1 12.4k
E19E19
Q3
MMBT3904
Q3
MMBT3904
1
32
CSNUB 10nF 500V CSNUB 10nF 500V E3E3
R5 470k R5 470k
R2 470kR2 470k
R9 270k R9 270k
M1
FDB33N25
M1
FDB33N25
G
DS
RX
OPT
RX
OPT
D5
GREEN
D5
GREEN
D2
BAV3004W
D2
BAV3004W
12
CF
1nF
100V
CF
1nF
100V
R8 4.7k R8 4.7k
D7 BAV3004W D7 BAV3004W
1 2
R1 470kR1 470k
Q2
MMBT3904
Q2
MMBT3904
1
32
E4E4
RIN
392k
RIN
392k
CX
10nF
100V
CX
10nF
100V
RG 10RG 10
RSS 34k RSS 34k
E20E20
RSNUB 100 RSNUB 100
D6
GREEN
D6
GREEN
RFB2 422k RFB2 422k
R10 200 R10 200
M2
FDB33N25
M2
FDB33N25
G
DS
U1U1
VDD
1GATE 8
SD
2OUT 7
FB 6
VSS
4BASE 5
TIMER
3
Q4
PZTA42
Q4
PZTA42
1
3 4
C1
470nF
25V
C1
470nF
25V
D3
BAV3004W
D3
BAV3004W
1 2
D4
BAV3004W
D4
BAV3004W
12
CG 10nF 100V CG 10nF 100V
R6 270k R6 270k
E6E6

6
dc1850aabf
DEMO MANUAL
DC1850A-A/DC1850A-B
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2012
LT 1012 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LT C for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LT C from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LT C currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LT C applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation

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