The maximum junction temperature of the IRS21084PBF is 150°C, as specified in the datasheet. However, it's recommended to keep the junction temperature below 125°C for reliable operation and to prevent thermal runaway.
The minimum input capacitance required for the IRS21084PBF can be calculated using the formula: Cin(min) = (Vcc * Icc) / (fsw * ΔVcc), where Vcc is the input voltage, Icc is the input current, fsw is the switching frequency, and ΔVcc is the input voltage ripple. Typically, a minimum of 10uF to 22uF is recommended.
The bootstrap capacitor is used to generate the high-side gate drive voltage for the power MOSFET. It's charged through the bootstrap diode during the off-time of the low-side MOSFET and provides the necessary voltage to turn on the high-side MOSFET.
To ensure proper biasing for high-frequency operation, make sure to provide a stable Vcc supply, use a low-ESR input capacitor, and add a 1kΩ to 10kΩ resistor in series with the bootstrap capacitor to prevent high-frequency oscillations.
For optimal performance, keep the power stage components (MOSFETs, diodes, and capacitors) close together and use a symmetrical layout to minimize parasitic inductances. Use a solid ground plane and a separate power plane for the input voltage. Keep the high-frequency nodes (e.g., bootstrap capacitor and gate drive signals) away from sensitive analog nodes.
IRS21084PBF datasheet
by International Rectifier
