TS19375

PWM Step-Up Controller

5/8

Version: B11

Function Description (Continue)

Input Capacitor Selection

The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input

capacitor impedance at the switching frequency shall be less than input source impedance to prevent high

frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must

be used.

The capacitor voltage rating should be at least 1.5 times greater than the input voltage, and often much higher

voltage ratings are needed to satisfy.

Output Capacitor Selection

The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The

output capacitor must have low impedance at the switching frequency. A low ESR capacitor sized for maximum

RMS current must be used. The low ESR requirements needed for low output ripple voltage. The capacitor voltage

rating should be at least 1.5 times greater than the input voltage, and often much higher voltage ratings are needed

to satisfy.

The ESR range of output capacitor is 30m~100mΩ at switch current more than 1.5A. Add a 4.7uF output bypass

capacitor in order to reduce output ripple effectively