DEMO MANUAL DC1699A LT6108-1/LT6108-2 High Side Current Sense Amplifier with Reference and a Comparator DESCRIPTION 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 PERFORMANCE SUMMARY SYMBOL PARAMETER VIN Input Supply Range comparator, while the DC1699A-B (LT6108-2) has a non latching comparator. Both current sense gain and current 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 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. (TA = 25°C) CONDITIONS MIN TYP MAX 2.7 VIOUT Measured Output Signal ILOAD = 100mA IOUT Output Load Current Range Thermal Limit of RSENSE UNITS 60 V 250 mV 4 A 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 OPERATING PRINCIPLES The LT6108 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. V+ 7 V+ LT6108 VBATT RIN 8 SENSEHI – 1 SENSELO + RSENSE ISENSE OUTA 6 4 VOUT ROUT V– dc1699a F01 Figure 1. Amplifier Operation dc1699af 1 DEMO MANUAL DC1699A BLOCK DIAGRAMS 7 V+ LT6108-1 100Ω 8 SENSEHI 3k SENSELO 3k 34V – + 1 OUTA V– 6 V– V+ V– 6V 200nA 2 EN/RST ENABLE AND RESET TIMING RESET V+ INC – 3 5 OVERCURRENT FLAG OUTC + V– V+ 400mV REFERENCE V– 4 dc1699a BD1 LT6108-1 7 V+ LT6108-2 100Ω 8 SENSEHI 3k SENSELO 3k 34V – + 1 OUTA V– V– 6V 6 V– V+ 100nA 2 EN V+ INC – 3 5 OVERCURRENT FLAG OUTC + V– 400mV REFERENCE V+ V– 4 dc1699a BD2 LT6108-2 dc1699af 2 DEMO MANUAL DC1699A QUICK START PROCEDURE 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 (positive) 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 button. 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. 20.0V RESET BUTTON 0.10A 250mV LOAD ϮϬϬɏ 250mV Figure 2. dc1699af 3 DEMO MANUAL DC1699A OPERATION Current Sense Gain Optional Settings 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. 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 damaging the TimerBlox® circuitry that is used to reset the comparator output. 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 reset to unlatch the comparator output and turn off the LED. Jumper Summary 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, remove R1 and R2 and install R14. To add filtering to the amplifier output, install C6. 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. dc1699af 4 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 1 1 DC1699A GENERAL BOM DC1699A 2 1 C4 Capacitor, 0.1μF 20% 0402 10V X5R 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 DC1699A-A TDK/C1005X5R1A104M 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 1 1 DC1699A GENERAL BOM DC1699A 2 1 U1 IC, LT6108IMS-2 DC1699A-B Linear Technology Corp. LT6108IMS-2 dc1699af 5 E6 E5 E8 1. ALL RESISTORS ARE IN OHMS, 0603 2. ALL CAPACTORS ARE IN MICRO FARADS, 0603 3. INSTALL SHUNTS AT J1 PIN 1+2 3 COUT EN/RST V+ THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. CUYLER L. APP ENG. SCALE = NONE CL APPROVALS 5 6 1 C6 OPT R6 100 * R2 806 R1 1.69k E4 E3 LTC CONFIDENTIAL FORCUSTOMER USE ONLY WWW.LINEAR.COM 1630 McCarthy Blvd. Milpitas, CA 95035 PH: (408) 432-1900 R14 OPT LT6108IMS8-2 LT6108IMS8-1 -A -B U1 OUT CIN IOUT 4A MAX E2 DATE 07/01/2010 APPR CUYLER L. ASSY DESCRIPTION PRODUCTION N/A DATE: SIZE 07/2010 IC NO. LT6108IMS8-1/-2 DEMO CIRCUIT 1699A SH 1 of 2 1 REV PRECISION CURRENT SENSE WITH COMPARATOR AND REFERENCE TITLE: SCHEMATIC CIN IOUT SENSE - PCB DES. SENSE + GND 0.1 Ohm 2512 R11 U1 LT6108IMS8* CUSTOMER NOTICE R3 10k 0402 7 8 RESET 2 R7 100 LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMERSUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. LED2 1206 LED R5 1k 0402 C7 0.1uF R17 0 OHM NOTES: UNLESS OTHERWISE SPECIFIED GND COUT V+ E1 3V 1 2 IN 3.3V-60V 3V 6 4 ECO REV 1 DEMO MANUAL DC1699A SCHEMATIC DIAGRAM dc1699af C1 1uF 1206 8 5 SHDN IN 4 V- SENSE OUT 2 1 2 1 1 2 JP1 RESET 3 C2 0.47uF 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. V+ 3 2 1 SET GND RST U4 DIV V+ OUT SCALE = NONE APP ENG. CUYLER L. CL 3 2 1 DIV V+ OUT 4 5 6 C4 0.1u 0402 R13 392k 0402 R12 1Meg 0402 3V EN/RST LTC CONFIDENTIAL FORCUSTOMER USE ONLY WWW.LINEAR.COM E7 1630 McCarthy Blvd. Milpitas, CA 95035 PH: (408) 432-1900 RESET RESET N/A DATE: SIZE IC NO. LT6108IMS8-1/-2 DEMO CIRCUIT 1699A 07/2010 SH 2 of 2 1 REV PRECISION CURRENT SENSE WITH COMPARATOR AND REFERENCE TITLE: SCHEMATIC LT6993CS6-1 SET GND TRIG U3 4 5 6 **COMPONENTS ARE OPTIONAL ON DC1699A-B ASSEMBLY R4 LT6991CS6 124k 0402 APPROVALS R9 249k 0402 PCB DES. OPT 2.7V-5V R16 AUTO CUSTOMER NOTICE MAN SW1 RESET C5 0.1uF 0402 0 3V LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMERSUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. R18 1M 0402 R10 10k 0402 R8 13.7k 0402 3.3V-60V R15 3V U2 LT3010EMS8 DEMO MANUAL DC1699A SCHEMATIC DIAGRAM dc1699af 7 V+ DEMO MANUAL DC1699A 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 application engineer. Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation dc1699af 8 Linear Technology Corporation LT 0911 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011