IRDC3838 Infineon

IRDC3838 TM SupIRBuck USER GUIDE FOR IR3838 EVALUATION BOARD DESCRIPTION Key features includes: Internal LDO, Pre-Bias TM The IR3838 SupIRBuck is an easy-to-use, startup, protection functions, such as hiccup fully integrated and highly efficient DC/DC current limit and thermal shutdown to give regulator. The onboard PWM controller and required system level security in the event of MOSFETs make IR3838 a space-efficient fault conditions. An output over-current protection function is implemented by sensing solution, providing accurate power delivery for the voltage developed across the on-resistance low output voltage applications. of the synchronous rectifier MOSFET for IR3838 is a versatile regulator which offers optimum cost and performance. programmability of switching frequency and This user guide contains the schematic and bill current limit while operates in wide input and of materials for the IR3838 evaluation board. output voltage range. The guide describes operation and use of the The switching frequency is programmable evaluation board itself. Detailed application information for IR3838 is available in the from 250kHz to 1.5MHz for an optimum IR3838 data sheet. solution. BOARD FEATURES V = +12V in V = +1.8V 0 10A out F = 600kHz s L = 0.6uH C = 4x10uF (ceramic 1206) + 1x330uF (electrolytic) in C =5x47uF (ceramic 0805) out 1IRDC3838 CONNECTIONS and OPERATING INSTRUCTIONS A well regulated +12V input supply should be connected to VIN+ and VIN-. A maximum 10A load should be connected to VOUT+ and VOUT-. The connection diagram is shown in Fig. 1 and inputs and outputs of the board are listed in Table I. IR3838 has only one input supply, the input voltage (Vin). Internal LDO circuitry generates Vcc voltage (=5.2V). One option for using a separate +5V supply for Vcc voltage, as required in a certain application, is to remove R15 (zero Ohm resistor), which disables the internal LDO circuit. In this case Vcc input should be a well regulated 4.5V-7.5V supply and it would be connected to Vcc+ and Vcc-. Table I. Connections Connection Signal Name VIN+ V (+12V) in VIN- Ground of V in VOUT+ V (+1.8V) out VOUT- Ground of Vout Vref Internal Reference-Voltage SEQ Sequence input Vcc+ VCC/LDO out pin Vcc- Connected to PGND Sync Synchronous input LAYOUT The PCB is a 4-layer board. All of layers are 2 Oz. copper. The IR3838 and other components are mounted on the top and bottom side of the board. Power supply decoupling capacitors, the Bootstrap capacitor and feedback components are located close to IR3838. The feedback resistors are connected to the output voltage at the point of regulation and are located close to IR3838. To improve efficiency, the circuit board is designed to minimize the length of the on-board power ground current path. 2