A good PCB layout for the IR21531PBF involves keeping the high-frequency switching nodes (e.g., pins 3 and 4) away from sensitive analog circuits, using a solid ground plane, and minimizing trace lengths and loops. It's also recommended to use a shielded cable for the bootstrap capacitor connection.
The bootstrap capacitor value depends on the switching frequency, output voltage, and desired ripple current. A general rule of thumb is to choose a capacitor with a value between 10nF to 100nF, with a voltage rating of at least 2x the output voltage. For example, for a 500kHz switching frequency and 300V output voltage, a 22nF, 600V capacitor would be a good choice.
The maximum allowable voltage on the VCC pin is 20V. To protect it from overvoltage, a voltage clamp or a zener diode can be used to limit the voltage to 18V or less. Additionally, a 1kΩ to 10kΩ resistor can be added in series with the VCC pin to limit the current and prevent damage.
To ensure proper biasing and configuration, follow the recommended application circuit in the datasheet, and pay attention to the voltage levels on the VCC, VIN, and VOUT pins. Also, make sure to choose the correct resistor values for the feedback network and the bootstrap capacitor. If unsure, consult the datasheet or contact International Rectifier's technical support.
The IR21531PBF has a maximum junction temperature of 150°C. To ensure reliable operation at high temperatures, use a heat sink with a thermal resistance of less than 10°C/W, and ensure good airflow around the device. Additionally, reduce the power dissipation by optimizing the switching frequency, output voltage, and current levels.
IR21531PBF datasheet
by International Rectifier
