IRDC3865 TM SupIRBuck USER GUIDE FOR IRDC3865 EVALUATION BOARD DESCRIPTION TM The IR3865 SupIRBuck is an easy-to-use, Additional features include: pre-bias startup, fully integrated and highly efficient DC/DC soft start, power good output, enable input with voltage regulator. The onboard constant on voltage monitoring capability and over/under voltage protection, making the device a very time hysteretic controller and MOSFETs make IR3865 a space-efficient solution that delivers flexible solution that is suitable for a broad up to 10A of precisely controlled output voltage range of applications. in a 4mm x 5mm QFN package. This user guide contains the schematic, bill of In addition to excellent light load and full load materials, and operating instructions of the efficiency, the IR3865 offers features such as: IRDC3865 evaluation board. Detailed product a 0.5V reference, programmable switching specifications, application information and performance curves at different operating frequency, temperature compensated over current protection, thermal shutdown and conditions are available in the IR3865 data optional forced continuous conduction mode. sheet. BOARD FEATURES V = +12V IN V = +5V CC V = +1.05V OUT I = 0 to 10A OUT F = 300kHz CCM S L = 1.5H C = 22F (ceramic 1210) + 68F (electrolytic) IN C = 47F (ceramic 0805) + 330F (POSCAP) OUT 1 IRDC3865 CONNECTIONS and OPERATING INSTRUCTIONS An input supply in the range of 7 to 16V should be connected from VIN to PGND. A maximum load of 10A may be connected to V and PGND. The connection diagram is shown in Fig. 1, and the OUT inputs and outputs of the board are listed in Table 1. IRDC3865 has two input supplies, one for biasing (VCC) and the other for input voltage (VIN). Separate supplies should be applied to these inputs. VCC input should be a well regulated 4.5V to 5.5V supply connected to VCC and PGND. Enable (EN) is controlled by the first switch of SW1, and FCCM option can be selected by the second switch of SW1. Toggle the switch to the ON position (marked by a solid square) to enable switching or to select FCCM. The absolute maximum voltage of the external signal applied to EN (TP4) and FCCM is +8V. Table 1. Connections Connection Signal Name VIN (TP2) VIN PGND (TP5) Ground for VIN VCC (TP16) VCC Input PGND (TP17) Ground for VCC Input VOUT (TP7) V (+1.05V) OUT PGND (TP10) Ground for V OUT EN (TP4) Enable Input LAYOUT The PCB is a 4-layer board. All layers are 1 oz. copper. IR3865 and other components are mounted on the top and bottom layers of the board. The power supply decoupling capacitors, bootstrap capacitor and feedback components are located close to IR3865. To improve efficiency, the circuit board is designed to minimize the length of the on- board power ground current path. 2