DEMO MANUAL DC1659A LT6109-1/LT6109-2 High Side Current Sense Amplifiers with Reference and Comparators DESCRIPTION Demonstration circuit 1659A features the LT®6109, a high side current sense amplifier with two comparators and a 400mV reference. The demo board circuit amplifies the voltage across an on-board current sense resistor, to provide a precision unipolar voltage output that is proportional to the sensed current. The board has two on-board comparators with latching outputs and an integrated 400mV reference that sets the threshold for the comparators. There are two versions of this demonstration circuit, A and B, depending on which version of the LT6109 is installed. The DC1659A-A (LT6109-1) has an inverting and a noninverting comparator input available, while the DC1659A-B (LT6109-2) has PERFORMANCE SUMMARY two inverting inputs available. Both current sense gain and current fault limits are set by on board resistors and are the same for both boards. The gain is set at 100V/V and the comparators are set to trip at current thresholds of 50mA and 300mA. 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) SYMBOL PARAMETER CONDITIONS VIN Input Supply Range VIOUT Measured Output Signal ILOAD = 100mA IIOUT Measured Output Current VIOUT = 1V MIN TYP 2.7 MAX 60 UNITS V 1 V 100 μA ILOAD Output Load Current Range Thermal Limit of RSENSE IQ IN Quiescent Current VIN = 12V 800 4 μA A VTHR1 Comparator1 Threshold VIOUT = 3.0V 300 mA VTHR2 Comparator2 Threshold VIOUT = 0.5V 50 mA OPERATING PRINCIPLES The LT6109 operates by amplifying the voltage drop across a sense resistor that is in series with the load. The sense inputs of the amplifier differentially measure the sense resistor voltage drop to control an internal variable current source that allows translation of the input voltage level to a level referenced to the GND. The circuit gain is set by the ratio of the output resistor to the input resistor. 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 DC1659 is shipped with a 100mΩ sense resistor, a gain of 100 and current fault thresholds of 50mA and 300mA. dc1659af 1 DEMO MANUAL DC1659A BLOCK DIAGRAMS LT6109-1 (DC1659A-A) LT6109-2 (DC1659A-B) 9 9 V+ LT6109-1 V+ LT6109-2 100Ω SENSEHI 3k SENSELO 3k 34V – 10 + 1 OUTA V– V – 6V 8 SENSEHI 3k SENSELO 3k V 200nA 2 EN/RST 2 EN/RST ENABLE AND RESET TIMING RESET V+ V+ INC2 + 3 UNDERCURRENT FLAG 7 3 OUTC2 OVERCURRENT FLAG – V– V+ V– 4 INC1 OUTC1 OVERCURRENT FLAG – OVERCURRENT FLAG 6 – V– 5 400mV REFERENCE V+ + OUTC1 7 V+ V– + 400mV REFERENCE V+ INC2 + V– 4 8 V– V+ 200nA ENABLE AND RESET TIMING RESET OUTC2 OUTA V– – 6V + 1 V– V+ 34V – – 10 100Ω INC1 6 V– 610912 F01 5 610912 F02 dc1659af 2 DEMO MANUAL DC1659A QUICK START PROCEDURE The DC1659A provides a simple way to evaluate the performance of the LT6109. Refer to Figure 1 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 1. 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. The comparators start in an unknown state and must be reset. This can be done by pressing the reset button. With the load shown in Figure 1 the comparator outputs should be: PART COUT1 COUT2 DC1659A-A LT6109-1 High High DC1659A-B LT6109-2 High Low 5. Measure the output voltage and confirm it corresponds to the load current. VIOUT = 10 • ILOAD for the factory installed resistors. 6. If able, sweep load current from 0mA to 300mA to verify the operation of the comparators. The LED will turn on when the comparator output has latched low. Use the reset circuitry to reset comparator output. 20.0V Reset 0.10A Load 200Ω 1.0V Figure 1. Test Setup dc1659af 3 DEMO MANUAL DC1659A OPERATION Current Sense Gain Optional Settings The gain of the LT6109 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 + R3)/R10. The gain error is primarily controlled by the precision of the resistors used. The factory resistors are a 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 R20 and install R21 (0Ω jumper). When R21 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 outputs. LED Indicators 3. There are a number of optional components that (not installed) allow the DC1659 to be tailored to a specific application: The LEDs indicate the state of the comparator outputs. When the LED is on, the comparator is latched low. When the LED is off, the comparator output is high. When the comparator output is latched low, the LT6109 must be reset to refresh the comparator output and to turn off the LEDs. 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 reset the latching comparators. In auto mode, the comparators will be continuously reset every 10 seconds. The factory default setting is manual mode. 2. To power the LT6109 from a supply separate from the load, remove R22 and connect the power supply to V+ turret. A) To free comparator input INC1, remove R2 and R3 and install R19. B) To free comparator input INC2, remove R1 and R2 and install R18. C) To add filtering to the amplifier output, install C6. 4. R9 can be set to the same value as R10 to reduce error caused by input bias current. Typically for values of R10 (less than 1k) and R9 can be omitted as the error is negligible. dc1659af 4 DEMO MANUAL DC1659A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION 1 2 MANUFACTURER/PART NUMBER 1 C1 Capacitor, 1μF 20% 1206 100V X7R TDK/C3216X7R2A105M 1 C2 Capacitor, 0.47μF 20% 0603 16V X5R AVX/0603YD474MAT2A 3 2 C4, C5 Capacitor, 0.1μF 20% 0402 10V X5R Taiyo Yuden/LMK105BJ104MV-F 4 1 C6 Capacitor, 0.1μF 20% 0603 X5R Optional 5 1 C7 Capacitor, 0.1μF 10% 0603 100V X7R 6 3 E1, E2, E8 Turret Terminal Mill Max 2501-2-00-80-00-00-07-0 7 7 E3-E7, E9, E10 Turret Terminal Mill Max 2308-2-00-80-00-00-07-0 8 1 JP1 Header, 3-Pin, 2mm SAMTEC TMM-103-02-L-S Murata/GRM188R72A104KA35D 9 1 JP1 Shunt SAMTEC 2SN-BK-G 10 2 LED1, LED2 Red1206 LED Panasonic/LN1251C 11 1 R1 Resistor, 2k 1% 0603 1/16W AAC/CR16-2001FM 12 1 R2 Resistor, 6.65k 1% 0603 1/16W Vishay/CRCW06036K65FKEA 13 1 R3 Resistor, 1.33k 1% 0603 1/16W AAC/CR16-1331FM 14 3 R4, R5, R14 Resistor, 10k 5% 0402 1/16W AAC/CR05-103JM 15 1 R6 Resistor, 118k 1% 0402 1/16W AAC/CR05-1243FM 16 2 R7, R8 Resistor, 1k 5% 0603 1/16W Vishay/CRCW04021K00JNED 17 1 R10 Resistor, 100Ω 1% 0603 1/16W Vishay/CRCW0603100RFKEA 18 1 R11, R22 Resistor, 0Ω 0402 1/16W Vishay/CRCW04020000Z0ED 19 1 R12 Resistor, 13.7k 1% 0402 1/16W AAC/CR05-1372FM 20 1 R13 Resistor, 249k 1% 0402 1/16W AAC/CR05-2493FM 21 1 R15 Resistor, 0.1Ω 1% 2512 2W IRC/LR2512LF-01-R100-F 22 1 R16, R23 Resistor, 1M 1% 0402 1/16W AAC/CR05-1004FM 23 1 R17 Resistor, 392k 1% 0402 1/16W AAC/CR05-3923FM 24 3 R18, R19, R21 Optional 25 2 R20, R9 Resistor, 0Ω 0603 1/16W AAC/CJ06-000M 26 1 SW1 Switch, Pushbutton Panasonic/EVQPPDA25 28 1 U2 IC, LT3010EMS8E#PBF Linear Technology Corp. 29 1 U3 IC, LT6993CS6-1#PBF Linear Technology Corp. 30 1 U4 IC, LT6991CS6#PBF Linear Technology Corp. 1 U1 IC, LT6109IMS-1 Linear Technology Corp. LT6109IMS-2 1 U1 IC, LT6109IMS-2 Linear Technology Corp. LT6109IMS-2 DC1659A-A 1 DC1659A-B 1 dc1659af 5 DEMO MANUAL DC1659A SCHEMATIC DIAGRAM dc1659af 6 DEMO MANUAL DC1659A SCHEMATIC DIAGRAM dc1659af 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. 7 DEMO MANUAL DC1659A 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 dc1659af 8 Linear Technology Corporation LT 0611 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2011