Linear Technology DC1699A Quick setup guide

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DEMO MANUAL DC1699A
DESCRIPTION
LT6108-1/LT6108-2
High Side Current Sense Amplifier
with Reference and a Comparator
Demonstration circuit 1699A features the LT
®
6108, a
high side current sense amplifier with a comparator and
a 400mV reference.
The demo board circuit amplifies the voltage across an
onboard current sense resistor, to provide a precision
unipolar voltage output that is proportional to the sensed
current. The board has one onboard comparator and an
integrated 400mV reference that sets the threshold for the
comparator. There are two versions of this demonstration
circuit, A and B, indicating which version of the LT6108
is installed. The DC1699A-A (LT6108-1) has a latching L, LT, LTC, LTM, TimerBlox, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
PERFORMANCE SUMMARY
OPERATING PRINCIPLES
comparator, while the DC1699A-B (LT6108-2) has a non
latching comparator. Both current sense gain and cur-
rent fault limits are set by onboard resistors and are the
same for both boards. The gain is set at 25V/V and the
comparator is set to trip at a current threshold of 500mA.
The key performance specifications are listed in the table
below.
Design files for this circuit board are available at
http://www.linear.com/demo
(TA= 25°C)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Range 2.7 60 V
VIOUT Measured Output Signal ILOAD = 100mA 250 mV
IOUT Output Load Current Range Thermal Limit of RSENSE 4A
IQA VIN Quiescent Current DC1699A-A VIN = 12V 800 μA
IQB VIN Quiescent Current DC1699A-B VIN = 12V 650 μA
VTHR Comparator Threshold VIOUT = 1.25V 500 mA
TheLT6108 operates by amplifying the voltage drop across
a sense resistor that is in series with the load. The voltage
drop at the amplifier inputs is translated, via the internal
variable current source, to a ground referenced signal at
the amplifier output. The circuit gain is set by the ratio of
the output resistor to the input resistor(see Figure 1). The
comparator thresholds are set by the internal reference
and the current trip points are set by dividing the output
resistance into a network of three resistors. The DC1699A
is shipped with a 100mΩ sense resistor, a gain of 25 and
current fault threshold of 500mA.
SENSEHI
LT6108
ISENSE
RSENSE
V+
7
V–
4
V+
RIN
VBATT
SENSELO
8
1OUTA 6
dc1699a F01
ROUT
VOUT
–
+
Figure 1. Amplifier Operation
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DEMO MANUAL DC1699A
BLOCK DIAGRAMS
LT6108-1
LT6108-2
100Ω
OUTA
–
+
–
+
7
8
16
INC 5
V+
dc1699a BD1
V+
V–
V–
V–
V–
V+
3k
V+
3k
SENSEHI
LT6108-1
SENSELO
200nA
RESET
OVERCURRENT FLAG
2EN/RST
3OUTC
34V 6V
ENABLE AND
RESET TIMING
V–
4
400mV
REFERENCE
100Ω
OUTA
–
+
–
+
7
8
16
INC 5
V+
dc1699a BD2
V+
V–
V–
V–
V–
V+
3k
V+
3k
SENSEHI
LT6108-2
SENSELO
100nA
OVERCURRENT FLAG
2EN
3OUTC
34V 6V
V–
4
400mV
REFERENCE
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DEMO MANUAL DC1699A
QUICK START PROCEDURE
Figure 2.
The DC1699A provides a simple way to evaluate the
performance of the LT6108. Refer to Figure 2 for proper
measurement equipment setup and follow the procedure
below:
1. With the power off, connect the power supply positive
to IN and the common to GND. With default board
settings the supply can range from 3.3V to 60V. If the
supply does not have an accurate current readout, a
DMM may be connected in series with the supply as
shown in Figure 2.
2. Connect a DMM or oscilloscope to the IOUT with the
common connection connected to ground.
3. Connect a load to the demo boards OUT terminal (posi-
tive) and ground. The load may be a power resistor,
active load instrument or a circuit of interest.
4. Turn on the power supply. If using the DC1699A-A ,
the comparator starts in an unknown state and must
be reset. This can be done by pressing the reset but-
ton. With the load shown in Figure 2 the comparator
outputs should be high.
5. Measure the output voltage and confirm it corresponds
to the load current. VIOUT = 2.5 • ILOAD for the factory
installed resistors.
6. If possible, sweep the load current from 0mA to 500mA
to verify the operation of the comparator. The LED will
turn on when the comparator output has gone low. If
using the DC1699A-A, use the reset circuitry to reset
the comparator output.
0.10A
20.0V
250mV
RESET BUTTON
LOAD
ϮϬϬɏ
250mV
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DEMO MANUAL DC1699A
OPERATION
Current Sense Gain
The gain of the LT6108 current sense amplifier is set by
the ratio of ROUT and RIN resistors. In the demo circuit this
means that the gain is set by the ratio of (R1 + R2 )/R7.
The gain error is primarily controlled by the precision of
the resistors used. The installed resistors are 1% tolerance
which will dominate the gain error. To reduce system gain
error, the resistors can be replaced with 0.1% resistors.
LED Indicator
The LED indicates the state of the comparator output.
When the LED is on, the comparator’s output is low. When
the LED is off, the comparators output is high. When the
comparator output is latched low, the LT6108-1 must be
resettounlatchthecomparatoroutputandturnofftheLED.
Jumper Summary
Reset (JP1): The Reset jumper has two settings for manual
or auto mode. In manual mode, the user must press the
reset button to trigger the LTC6993 to send the 5μs pulse
that resets the latching comparators. In auto mode, the
LTC6991 will continuously reset the comparators every
10 seconds. The factory default setting is manual mode.
Optional Settings
1. For supply voltages below 3.3V, remove R15 and install
R16 (0Ω jumper). When R16 is installed, the supply
voltage must stay between 2.7V to 6V to prevent dam-
aging the TimerBlox
®
circuitry that is used to reset the
comparator output.
2. To power the LT6108 from a supply separate from the
load, remove R17 and connect the power supply to V+
turret. The input cannot go more than 33V below V+.
3. There are a number of optional components (not
installed) that allow the DC1699 to be tailored to a
specific application:
To disconnect comparator input CIN from IOUT, re-
move R1 and R2 and install R14.
To add filtering to the amplifier output, install C6.
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DEMO MANUAL DC1699A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
DC1699A Genreral BOM
1 1 C1 Capacitor, 1μF 20% 1206 100V X7R AVX 12061C105MAT2A
2 1 C2 Capacitor, 0.47μF 20% 0603 16V X5R AVX 0603YD474MAT2A
3 1 C5 Capacitor, 0.1μF 10% 0402 16V X5R AVX 0402YD104KAT2A
4 1 C7 Capacitor, 0.1μF 10% 0603 100V X7R Murata/GRM188R72A104KA35D
5 3 E1, E2, E6 TURRET TERMINAL Mill Max 2501-2-00-80-00-00-07-0
6 5 E3-E5, E9, E10 TURRET TERMINAL Mill Max 2308-2-00-80-00-00-07-0
7 1 LED2 RED1206 LED Panasonic/LN1251C
8 1 R1 Resistor, 1.69k 1% 0603 1/16W VISHAY/CRCW06031K69FKEA
9 1 R2 Resistor, 806 1% 0603 1/16W VISHAY/CRCW0603806RFKLEA
10 2 R3, R10 Resistor, 10k 5% 0402 1/16W VISHAY/CRCW040210K0JNED
11 1 R5 Resistor, 1k 5% 0603 1/16W VISHAY/CRCW06031K00JNEA
12 2 R6, R7 Resistor, 100 1% 0603 1/16W VISHAY/CRCW0603100RFKEA
13 1 R8 Resistor, 13.7k 1% 0402 1/16W VISHAY/CRCW040213K7FKED
14 1 R11 Resistor, 0.1Ω 1% 2512 2W IRC/LR2512LF-01-R100-F
15 0 R14 OPTIONAL
16 2 R15, R17 Resistor, 0Ω 0603 1/16W VISHAY/CRCW06030000Z0EA
17 1 U2 IC, LT3010EMS8E#PBF Linear Technology Corp.LT3010EMS8E#PBF
DC1699A-A
1 1 DC1699A GENERAL BOM DC1699A
2 1 C4 Capacitor, 0.1μF 20% 0402 10V X5R TDK/C1005X5R1A104M
3 1 JP1 HEADER, 3-PIN SAMTEC TSW-103-07-L-S
4 1 JP1 SHUNT SAMTEC SNT-100-BK-G
5 1 R4 Resistor, 124k 1% 0402 1/16W VISHAY/CRCW0402124KFKED
6 1 R9 Resistor, 249k 1% 0402 1/16W VISHAY/CRCW0402249KFKED
7 2 R12, R18 Resistor, 1M 1% 0402 1/16W VISHAY/CRCW04021M00FKED
8 1 R13 Resistor, 392k 1% 0402 1/16W VISHAY/CRCW0402392KFKED
9 1 SW1 Switch, push button Panasonic/EVQPPDA25
10 1 U1 IC, LT6108IMS-1 Linear Technology Corp. LT6108IMS-1
11 1 U3 IC, LTC6993CS6-1#PBF Linear Technology Corp. LTC6993CS6-1#PBF
12 1 U4 IC, LTC6991CS6#PBF Linear Technology Corp. LTC6991CS6#PBF
DC1699A-B
1 1 DC1699A GENERAL BOM DC1699A
2 1 U1 IC, LT6108IMS-2 Linear Technology Corp. LT6108IMS-2
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DEMO MANUAL DC1699A
SCHEMATIC DIAGRAM
RESET
R1 1.69k R2 806
R3 10k
12
LED2 1206 LED
R5 1k
E4
E5
E1
E6
E2
R6 100
R7 100
E3
R14 OPT
R11 0.1 Ohm
IN OUT
IOUT
CIN
COUT
GND
3.3V-60V
C6 OPT
C7
0.1uF
E8
R17 0 OHM
NOTES: UNLESS OTHERWISE SPECIFIED
1. ALL RESISTORS ARE IN OHMS, 0603
2. ALL CAPACTORS ARE IN MICRO FARADS, 0603
3. INSTALL SHUNTS AT J1 PIN 1+2
3V
3V
V+ ASSY
-A -B
LT6108IMS8-1 LT6108IMS8-2
U1
*
SENSE - 1
SENSE +
8
V+
7
CIN 5
COUT
3
EN/RST
2
GND
4
IOUT 6
U1 LT6108IMS8*
PRECISION CURRENT SENSE WITH COMPARATOR AND REFERENCE
07/2010
LT6108IMS8-1/-2
SH 1 of 2
1630 McCarthy Blvd.
Milpitas, CA 95035
PH: [phone]
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT
LTC CONFIDENTIAL FOR-
TITLE: SCHEMATIC
IC NO. REV
1
APPROVALS
CL
CUYLER L.
PCB DES.
APP ENG.
DEMO CIRCUIT 1699A
WWW.LINEAR.COM
DATE:
SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS
PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND
AFFECT CIRCUIT PERFORMANCE OR RELIABILITY.
CONTACT LINEAR TECHNOLOGY APPLICATIONS
THIS CIRCUIT IS PROPRIETARY TO
USE WITH LINEAR TECHNOLOGY PARTS.
SIZE
N/A
SCALE = NONE
CUSTOMER USE ONLY
TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-
THE CUSTOMER'S RESPONSIBILITY TO VERIFY
PRINTED CIRCUIT LAYOUT MAY SIGNIFICANTLY
ENGINEERING FOR ASSISTANCE.
LINEAR TECHNOLOGY AND SUPPLIED FOR
ECO REV DESCRIPTION APPR DATE
1 PRODUCTION CUYLER L. 07/01/2010
2512 4A MAX
0402
0402
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DEMO MANUAL DC1699A
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
RESET
RESET
C1 1uF C2
0.47uF
R9 249k
E7
2 1SW1
OUT 6
V+ 5
DIV 4
SET
3
GND
2
TRIG
1
U3
LT6993CS6-1
C4 0.1u
R8 13.7k
R10 10k
C5 0.1uF
JP1
OUT 6
V+ 5
DIV 4
SET
3
GND
2
RST
1
U4
LT6991CS6
R4 124k
R12 1Meg R13 392k
EN/RST
IN
8
SHDN
5
OUT 1
SENSE 2
V-
4
U2 LT3010EMS8 R15
0
R16 OPT
RESET AUTOMAN
V+
V+
3V
3V
3V
12 3
R18 1M
PRECISION CURRENT SENSE WITH COMPARATOR AND REFERENCE
07/2010
LT6108IMS8-1/-2
SH 2 of 2
1630 McCarthy Blvd.
Milpitas, CA 95035
PH: [phone]
LTC CONFIDENTIAL FOR-
TITLE: SCHEMATIC
IC NO. REV
1
APPROVALS
CL
CUYLER L.
PCB DES.
APP ENG.
DEMO CIRCUIT 1699A
WWW.LINEAR.COM
DATE:
SIZE
N/A
SCALE = NONE
CUSTOMER USE ONLY
**COMPONENTS ARE OPTIONAL ON
DC1699A-B ASSEMBLY
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT
SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS
PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND
AFFECT CIRCUIT PERFORMANCE OR RELIABILITY.
CONTACT LINEAR TECHNOLOGY APPLICATIONS
THIS CIRCUIT IS PROPRIETARY TO
USE WITH LINEAR TECHNOLOGY PARTS.
TO DESIGN A CIRCUIT THAT MEETS CUSTOMER- THE CUSTOMER'S RESPONSIBILITY TO VERIFY
PRINTED CIRCUIT LAYOUT MAY SIGNIFICANTLY
ENGINEERING FOR ASSISTANCE.
LINEAR TECHNOLOGY AND SUPPLIED FOR
3.3V-60V 2.7V-5V
0402 0402
0402
0402
0402
0402
0402
0402
0402
1206
RESET
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DEMO MANUAL DC1699A
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011
LT 0911 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) 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 LTC 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 LTC 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. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC 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 LTC applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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