The AP3981B is a high performance power switcher integrated with a primary side regulation controller and an N-channel power MOSFET. It can be used for battery charger and adaptor applications, accurate Constant Voltage (CV) and Constant Current (CC) can be achieved without an opto-coupler and secondary control circuitry.
The AP3981B operates in Pulse Frequency Modulation (PFM) mode and peak current Amplitude Modulation (AM) mode to form a fine tune frequency curve within the whole power range. Therefore, the AP3981B can achieve high average efficiency and improve audible noise.
The AP3981B provides comprehensive protections without additional circuitry. It contains VCC over voltage protection, output over voltage protection, output under voltage protection, output short circuit protection, cycle-by-cycle current limit, open loop protection, and internal OTP, etc.
The AP3981B is available in SO-7 package.
Set-Top Box (STB) Power Supply
Primary-Side Control for Eliminating Opto-Coupler
Built-In 650V Power MOSFET
75mW No-Load Input Power
Flyback Topology in DCM Operation
External Adjustable Line Compensation for CC
Fixed Internal Cable Compensation
Multiple Segment AM/PFM Control Mode to Improve Audio Noise and Efficiency
Frequency Jitter to Improve System EMI
Capacitive Load Start-Up Capability
Valley-On for the Higher Efficiency and Better EMI Behavior
Secondary-Side Over Voltage Protection (SOVP)
Secondary-Side Under Voltage Protection (SUVP)
Output Short Circuit Protection (SCP)
Transformer Saturation Protection (TSP) via Primary Peak