QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY LTC3738CUHF and LTC3731CUH DESCRIPTION Demonstration circuits 721A-A and 721A-B are high current step-down converters for Intel VRM/VRD10 and VRM9 processor power applications. The demo circuits feature the current-mode PolyPhaseTM controllers LTC3738CUHF and LTC3731CUH. The input voltage is from 8V to 14V and the output voltage is controlled by the VID setting. DC721A-A is a 6-phase LTC3738 and LTC3731 supply that can provide up to 120A output current. DC721A-B is a single LTC3738 3-phase 65A output supply. Both LTC3738CUHF and LTC3731CUH controllers are in the QFN packages to minimize the supply footprint size and improve the thermal performance. The LTC3738 controller has 6 VID pins to program the output voltage according to Intel VRM9 or VRM/VRD10 requirement. Accurate active voltage positioning (AVP) is implemented with LTC3738 to meet Intel’s tight load line regulation requirement. Optional 0.1% external voltage reference and external Op-Amp compensation circuits are also available on DC721A-A and DC721A-B for applications requiring <0.5% output voltage regulation accuracy and optimum transient response. Design files for this circuit board are available. Call the LTC factory. LTC, PolyPhase are trademarks of Linear Technology Corporation Table 1. Performance Summary (TA = 25°C) PARAMETER TEST CONDITION VALUE Minimum Input Voltage 8V Maximum Input Voltage 14V Controlled by VID setting: Output Voltage VOUT Meet Intel VRM9 and VRM/VRD10 static and transient specifications VRM9: 1.100V-1.850V, 25mV VID step VRM/VRD10: 0.8375V-1.6000V, 12.5mV VID step DC721A-A, 6-phase LTC3738+3731 design 120 ADC DC721A-B, 3-phase LTC3738 design 65 ADC DC721A-A, VIN = 12V, VOUT=1.5VVID, IOUT = 120A 87.6% Typical, See Figure 1 DC721A-B, VIN = 12V, VOUT=1.5VVID, IOUT = 65A 87.6% Typical Output Voltage Load Line DC721A-A, VIN = 12V, VOUT=1.35VVID See Figure 2 Output Load Transient Response DC721A-A, VIN = 12V, VOUT=1.5VVID See Figure 3 Maximum Continuous Output Current Efficiency QUICK START PROCEDURE Demonstration circuits 721A-A and 721A-B are easy to set up to evaluate the performance of the LTC3738CUHF and LTC3731CUH. Refer to Figure 4 for proper measurement equipment setup and follow the procedure below: 1. +5V Select INT 5V DLC BIAS DLC VRM SELECT INT ON OFF OFF VRM10 Place jumpers in the following positions: 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 2. With power off, connect the input power supply to Vin and GND. Connect an active load to VOUT+ and VOUT-. Preset the load to 0A. 3. Set the VID dip-switch S1 as follows: B4 B3 B2 B1 B0 B5 0 1 1 1 0 1 NOTE: Make sure that the input voltage does not ex- ceed 14V. 4. 5. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. With above VID setting, the output voltage should be within 1.391V-1.441V at 65A load current. NOTE: The maximum current of DC721A-A is 120A and DC721A-B is 65A. A cooling fan is needed to limit board temperature rise if output current is higher than 50A for DC721A-B or 90A for DC721A-A. Turn on the power at the input. Check for the proper output voltages. With above VID setting, the output voltage should be within 1.450V-1.500V at 0A load. 2 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY Efficiency vs. Load Current 95.00% 85.00% Efficiency (%) 75.00% 65.00% VOUT 55.00% DC721A, 6-phase 120A design Vin=12V, Vo=1.5V, Io(max)=120A 45.00% VCore_max VCore_min 35.00% 25.00% 0 20 40 60 80 Load Current (A) 100 120 Figure 1. Measured efficiency vs. load current Figure 2. Output load line meets Intel VRD10 spec Figure 3 Load transient @ 12VIN, 1.5VO of DC721A-A 3 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B Iout V Current Shunt Load 0-120A 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY Optional 5V bias Current Shunt V Vout V Iin V Vin Figure 4. Test Setup of DC721A-A and DC721A-B 4 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY DC721A-A – 6 Phase 120A 5 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 6 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 7 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 8 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 9 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY DC721A-B – 3 Phase 65A 10 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 11 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 12 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 13 QUICK START GUIDE FOR DEMONSTRATION CIRCUITS 721A-A/B 6-PHASE 120A / 3-PHASE 65A HIGH EFFICIENCY VRM9/VRD10 POWER SUPPLY 14