AP3125 Robust Green-Mode PWM Controllers

The AP3125 family current mode PWM controllers from Diodes Incorporated are optimized for high performance, low standby power in cost effective offline fly-back converters. They are available in SOT26 package.

The AP3125 has three modes of operation to minimize power losses dependent on load.

1. Fixed 65 kHz / 100 kHz PWM switching frequency: under full-load.
2. Green mode: At lighter loads the AP3125 automatically switches to PFM with switching frequency fold-back, improving system efficiency. A 20 kHz 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.

The AP3125 family includes comprehensive protection features such as cycle-by-cycle current limit (OCP), V_CC over-voltage protection (VOVP), internal OTP, over-load protection (OLP).

The AP3125B/HB has additional brownout (BNO) and line over-voltage protection (LOVP).

The AP3125A/V/R/L/HA has different versatile latch/auto protection functions.

The AP3125HB/HA has a 100 kHz nominal switching frequency plus.

Features

• Three modes of operations: 65 kHz / 100 kHz PWM mode, green-mode and burst mode improves efficiency across all load levels
• Frequency dithering in 65 kHz / 100 kHz PWM and green modes reduces EMI emission
• Internal slope and line compensation simplifies the feedback loop design making a more robust design
• Overcurrent protection, V_CC overvoltage protection, internal OTP, and over-load protection increase system reliability and robustness
• Built-in brownout and line over-voltage protection (AP3125B/HB) protect the system from faults and transients
• CTRL pin versatile protection (AP3125A/V/R/L/HA) provides external OTP / OVP with minimal number of components

Applications

• Switching AC-DC adapter/charger
• ATX / BTX auxiliary power
• Set-top box (STB) power supply
• Open frame switching power supply