AS3899

Domestic LLC half bridge resonant controller chip

The AS3899A is a high-performance, high-precision resonant mode two-terminal controller designed for LLC half-bridge resonant circuit control applications. It provides a complementary duty cycle of 50% : the high voltage side switch and the low voltage side switch are switched on/off in 180° reverse phase in exactly the same time. The controller modulated and stabilized the output voltage by adjusting the operating frequency of the system. AS3899A uses a novel MOSFET zero-voltage detection method to insert adaptive dead time between the turn-off and turn-on of two MOSFETs to ensure soft switching, low EMI and high efficiency of the system. To prevent output voltage overshoot during startup, the AS3899A provides a user-configurable soft start process that starts the switching frequency from a set maximum and then gradually decays to a steady-state resonant frequency point controlled by the loop, while also avoiding runaway impulse current during startup.

The AS3899A provides programmable burst mode control under no-load or light load to minimize magnetization current losses and frequency-dependent losses. The temperature return function, which decreases the output current as the temperature increases, can keep the system working in high temperature environment. The AS3899A also provides a user-optional front PFC controller interface for synchronous control of the PFC controller. The AS3899A is a highly integrated controller in a SOP16 package that simplifies system design. The internal oscillator supports switching frequencies from 40kHz to 400kHz. The AS3899A provides complete system protection features, including capacitor mode detection, line voltage undervoltage protection, VCC undervoltage lock, VCC overvoltage protection, load overcurrent protection, output overvoltage protection and overtemperature protection.

Product advantages:

• High precision oscillator

• No PFCS are supported

• Adaptive dead-time control

• Programmable soft boot

• Minimum working frequency and maximum working frequency can be programmed

• Primary constant current mode/overpower protection mode

• Capacitive pattern detection

• Light load burst operation mode