DEMO MANUAL DC1741A LTC4370 Two-Supply Diode-OR Current Balancing Controller DESCRIPTION Demonstration circuit DC1741A features the LTC4370, a two supply diode-OR current sharing controller in a typical 2.9V to 18V, 16A sharing application. The maximum MOSFET voltage drop VFR = VIN – OUT is set with an external resistor, up to 600mV. A fast gate turn-on reduces the load voltage droop during supply switchover. If the input supply fails or is shorted, a fast turn-off minimizes the transient reverse current. Disabling the load sharing function turns the LTC4370 into a dual ideal diode controller. Two enable input pins, EN1 and EN2, allow enabling and disabling each rail’s MOSFET individually while the MOSFETs’ inherent diodes create diode-OR connection when the MOSFETs are disabled. The LTC4370 provides a rich PERFORMANCE SUMMARY SYMBOL PARAMETER VIN VIN1 and VIN2 Input Voltage Operating Range • Elimination of "Share Bus” • Reverse Current Blocking • Elimination of Shoot-Through Current During Start-Up or Faults 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. MIN MAX UNITS 18 VCC V With External VCC Supply 2.9 0 VIN1, VIN2 ≤ VCC 2.9 6.0 V 5 5.5 V 0 ±2 mV VCC(REG) VCC Regulated Voltage VEA(OS) Error Amplifier Input Offset gm(EA) Error Amplifier Gain VFR Forward Regulation Voltage (VIN – VOUT) VIN =1.2V, VCC = 5V VIN =12V ΔVGATE MOSFET Gate Drive (GATE-VIN) IGATE GATE1, GATE2 Fast Pull-Up Current GATE1, GATE2 Fast Down-Up Current GATE1, GATE2 Off Pull-Down Current VEN(TH) EN1, EN2 Threshold Voltage Maximum Continuous Load Current • Elimination of the Need for Active Control of Input Supplies CONDITIONS VCC External Supply Operating Range IOUT • Load Sharing Between Two Supplies Specifications are at TA = 25°C VCC(EXT) ΔVGATE(ON) MOSFET On-Detect Threshold (GATE-VIN) set of features to support shared current diode-ORed applications including: 4.5 TYP 150 μS 2 2 12 25 25 50 mV mV VFWD = 0.2V; I = 0, –1μA; Highest VIN = 12V VFWD = 0.2V; I = 0, –1μA; Highest VIN = 2.9V 10 4.5 12 7 14 9 V V VFWD = 0.4V, ΔVGATE = 0V, CPO = 17V VFWD = –2V, ΔVGATE = 5V, Corresponding EN =1V, ΔVGATE = 2.5V –0.9 0.9 65 –1.4 1.4 110 –1.9 1.9 160 A A μA EN Falling 580 600 620 mV FETON Transitions High 0.28 0.7 1.1 V 16.6 A Sharing active, limited by SUM85N03 FET Dissipation dc1741af 1 DEMO MANUAL DC1741A OPERATING PRINCIPLES The LTC4370 controls N-channel MOSFETs, M1 and M2, to share the load between two input rails.The error amplifier compares OUT1 and OUT2, and controls servo amplifiers which regulate MOSFET forward voltage drop to VFR. Combined action of the error amplifier and servo amplifiers forces OUT1 and OUT2 to be equal and as a result the rail currents are equal. The board RANGE resistor R3 = 30.1k defines maximum regulation voltage range as 265mV to 375mV. The board is assembled with SUM85N03-06P N-channel MOSFETs, which in a single channel application has current capability up to 20A. In the load share mode the installed components guarantee continuous proper load sharing up to 16.6A total load. For a short test time of 3 to 5 seconds it is possible to double this load. Two LEDs, OFF1 and OFF2, indicate the MOSFETs’ status. Each LED lights up, when the gate voltage is less than 0.7V above VIN. Pay special attention to the power supply features used with the LTC4370. This controller may not work properly with supplies utilizing synchronized rectification in the output stage unless the internal circuit of the supply has the ability to limit negative current or to block it completely. Exercise caution when using the controller with this type of supply unless it is determined that it contains the required circuitry. dc1741af 2 DEMO MANUAL DC1741A QUICK START PROCEDURE Demonstration circuit DC1741A is easy to set up to evaluate the performance of the LTC4370. Refer to Figure 1 for proper measurement equipment setup for load share observation. 1. Turn both supplies on. Adjust two 5V supplies’ outputs to a 215mV difference, which equals the minimum ΔVIN(MIN) load share breakpoint (265mV–50mV). Load the LTC4370 output with minimal current so that both supplies contribute current to the common load. Increase load up to 35A and observe the LTC4370 operation mode with accurate load sharing. It is easy to estimate load share accuracy by measuring a voltage between two sense resistors. Since the MOSFETs will be dissipating excessive power, limit this measurement to 3 to 5 seconds when at the 35A level. 2. Reduce the load current to a total of 7.5A. Adjust the two 5V supplies’ outputs to a voltage difference of 373 mV which equals the maximum ΔVIN(MAX) load share breakpoint (375mV–2mV). As the difference between power supplies output is greater than the maximum voltage regulation, the LTC4370 channel with the higher voltage will provide most of the current. Increase the voltage until all of the current is provided by the higher voltage supply. This is the point at which the MOSFET of the higher voltage channel MOSFET is fully enhanced while the MOSFET of the lower channel voltage is completely cut off. Observe that the LED of the lower supply is illuminated. VARIABLE LOAD + POWER SUPPLY 1 – mV + POWER SUPPLY 2 – DC1741A F01 Figure 1. Load Share Performance Measurement dc1741af 3 DEMO MANUAL DC1741A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Cap., X7R, 0.18μF, 25V, 10%, 0805 AVX, 08053C184KAT2A Required Circuit Components 1 1 CC 2 1 CVCC Cap., X7R, 0.1μF, 50V, 10%, 0805 AVX, 08055C104KAT2A 3 2 C1, C2 Cap., X7R, 0.039μF, 50V, 10%, 0805 AVX, 08055C393KAT2A 4 2 D1, D2 LED, RED Panasonic, LN1251C-TR 5 2 D3, D4 Current Limiting Diode, 3.2V, SOD-80 Central Semi. Corp. CCLM3500 6 7 E1, E2, E3, E4, E5, E7, E8 Turret, Testpoint 0.063" Mill-Max, 2308-2-00-80-00-00-07-0 7 4 J1, J2, J4, J5 Connector, Banana Jack Keystone, 575-4 8 2 M1, M2 MOSFET N-Channel, 30V, D2PAK Vishay, SUM85N03-06P-E3 9 2 R1, R2 Res., WSL 0.002 1W, 1%, 2512 Vishay, WSL25122L000FEA 10 1 R3 Res., Chip 30.1k, 0.1W 1%, 0805 Vishay, CRCW080530K1FKEA 11 2 R4, R6 Res., Chip 10k, 0.1W, 5%, 0805 Vishay, CRCW080510K0JNEA 12 0 R5, R7 Res., 0805 OPT 13 1 U1 I.C., Diode-OR Load Share Cont., DFN16DE-4 × 3 Linear Technology Corp., LTC4370CDE dc1741af 4 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. D C B A GND VINB 18V MAX EN2 EN1 VCC VINA 18V MAX E8 J5 E7 J4 E5 E2 E3 E1 J1 1 1 R6 10K R4 10K R5 OPT 2 17 15 14 EN2 12 GATE1 4 6 50V C2 0.039uF VIN2 CPO2 3 7 8 9 10 2 3 THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE DESCRIPTION 2ND PROTOTYPE OFF2 D2 RED D4 LN1251C-TR CCLM3500 1 2 2 1 R2 0.002 1W 1% 2512 OFF1 D1 RED D3 LN1251C-TR CCLM3500 2 2 1 R1 0.002 1W 1% 2512 1 2 REV 5 E4 J2 OUTPUT TECHNOLOGY DATE: N/A SIZE IC NO. 4 01/17/2012, 11:31 AM DEMO CIRCUIT 1741A LTC4370CDE 5 SHEET 1 OF 1 2 REV. TWO-SUPPLY DIODE-OR CURRENT SHARING CONTROLLER 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 www.linear.com Fax: (408)434-0507 LTC Confidential-For Customer Use Only 1. ALL RES ARE IN OHMS, 0805. 2. ALL CAP ARE IN MICROFARAD, 0805. DATE VLADIMIR O. 01-17-12 APPROVED REVISION HISTORY NOTES: UNLESS OTHERWISE SPECIFIED _ ECO 4 TITLE: SCHEMATIC CC 0.18uF FETON2 FETON1 APPROVALS M2 SUM85N03-06P 5 GATE2 COMP OUT2 FETON2 FETON1 U1 OUT1 LTC4370CDE RANGE EP GND VCC EN1 CUSTOMER NOTICE RANGE 1 R3 30.1k CVCC 0.1uF 16 13 VIN1 11 CPO1 50V C1 0.039uF M1 SUM85N03-06P 3 LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES. KIM T. VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APP ENG. VLADIMIR O. APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. R7 OPT 2 D C B A DEMO MANUAL DC1741A SCHEMATIC DIAGRAM dc1741af 5 DEMO MANUAL DC1741A 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 dc1741af 6 Linear Technology Corporation LT 0912 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2012