IRDC38064-P1V2 TM SupIRBuck USER GUIDE FOR IR38064 EVALUATION BOARD DESCRIPTION The IR38064 is a synchronous buck converter with a PMBus interface, providing A temperature and bias compensated output a compact, high performance and flexible over-current protection function is implemented solution in a small 5mmx7mm PQFN by sensing the voltage developed across the package. on-resistance of the synchronous rectifier Key features offered by the IR38064 include MOSFET for optimum cost and performance. I2C/PMBus configurability of output voltage, soft-start, input UVLO, input overvoltage This user guide contains the schematic and bill protection, output overvoltage protection, of materials for the IR38064 evaluation board. output overcurrent protection, Power Good, The guide describes operation and use of the thermal protection and switching frequency. evaluation board itself. Detailed application Additionally, the IR38064 also features information for IR38064 is available in the enhanced line/ load regulation with feed IR38064 data sheet. forward, external frequency synchronization with smooth clocking, internal LDO, true differential remote sensing and pre-bias start-up. BOARD FEATURES PVin = +12V (+ 13.2V Max), No Vcc required. V = +1.2V 0-35A out F =600kHz s L= 0.150uH C = 4x22uF (ceramic 1206) + 1x330uF (electrolytic, optional) in C =10x47uF (ceramic 0805) out 3/21/2017 1 IRDC38064-P1V2 CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +12V input supply should be connected to PVin+ and PVin-. A maximum of 35A load should be connected to VOUT+ and VOUT-. The inputs and output connections of the board are listed in Table I. IR38064 needs only one input supply and internal LDO generates Vcc from PVin. Another internal LDo generates the 1.8V needed by the internal digital circuits. If operation with external Vcc is required, then R25 should be removed and external Vcc can be applied between Vcc+ and Vcc- pins. Vin pin and Vcc pins should be shorted together for external Vcc operation by installing R24. For tracking operation R27 should be populated with a 0 ohm resistor. For normal, non-tracking operation, R27 should not be populated and a 100 kOhm resistor should be connected from the Track En pin to P1V8 . The board is configured for remote sensing. If local sense is desired, R8 should be uninstalled and R16 should be installed instead. I2C/PMBus communication is established through the 4 pin header which allows connection to the SCL/SDA/SALERT and GND lines from the host/dongle. For proper operation in digital communications mode, R35 must always be populated. External Enable signal can be applied to the board via exposed Enable pad and R18 should be removed for this purpose. Table I. Connections Connection Signal Name PVin+ PVin (+12V) PVin- Ground of PVin Vout+ Vout(+1.2V) Vout- Ground for Vout Vcc+ Vcc Pin Vcc- Ground for Vcc input Enable Enable PGood Power Good Signal LAYOUT The PCB is a 6-layer board. All of layers are 2 Oz. copper. The IR38064 and most of the passive components are mounted on the top side of the board. Power supply decoupling capacitors and feedback components are located close to IR38064. The feedback resistors are connected to the output of the remote sense amplifier of the IR38064 and are located close to the IR38064. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. Separate power ground and analog ground are used and may be connected together using a 0 ohm resistor. 3/21/2017 2