The AP31261 current-mode PWM controller is optimized for use in high-performance, low-standby power, cost effective, offline flyback converters. It is available in the SOT26 package. AP31261 has three modes of operation to minimize power losses dependent on load.
1.Fixed 65kHz PWM switching frequency: under full-load.
2.Green Mode: At lighter loads the AP31261 automatically switches to PFM with switching frequency fold-back, improving system efficiency. A 20kHz minimum switching frequency avoids audible noise.
3.Burst Mode: Under Light- or No-load to minimize standby power. Frequency dithering is built-in to reduce EMI emissions. AP31261 includes comprehensive protection features such as cycleby-cycle current limit (OCP), VCC Overvoltage Protection (VOVP), internal OTP, and Overload Protection (OLP). The AP31261 has additional short protection for the current sense pin which protects the system from Bus capacitor open and current sense resistor short conditions.