Overview

The CX78GD048H is a quasi-resonant flyback power conversion chip with integrated D-GaN, designed for isolated flyback switching power supplies targeting high performance, low standby power, low cost, and high efficiency within 36W.

Under no-load, light-load, or heavy-load conditions, the CX78GD048H automatically switches its operating mode and frequency, which are internally adjusted by the chip. Under light load, the chip operates in green mode to reduce losses and improve overall system efficiency.

The CX78GD048H requires only a very low current for startup and operation, allowing the use of high-value resistors in the startup circuit to further reduce standby power consumption. The chip incorporates a built-in slope compensation circuit to prevent sub-harmonic oscillations and improve system stability when operating at large duty cycles. It features a built-in leading-edge blanking time to eliminate the impact of diode reverse recovery current in the snubber network. Frequency jittering technology is employed to effectively improve the system's EMI performance. The burst mode frequency is set above the audio range (22kHz) to avoid audible noise during operation.

The CX78GD048H integrates multiple protection features, including cycle-by-cycle current limiting (VCS_LIM), VDD over-voltage protection (OVP), VDD over-voltage clamp, under-voltage lockout (UVLO), over-temperature protection (OTP), input/output over/under-voltage protection, and external NTC support. The internal soft-driver structure further enhances the system's EMI characteristics.

Features

- Built-in D-GaN Power Transistor

- Standby Power Consumption Less Than 75mW for Full Input Voltage Range

- Full-Range Operation in Quasi-Resonant Mode

- Wide VDD Supply: VDD = 6.5V - 78.5V

- Built-in Soft Start to Reduce Vds Stress on the Power Transistor

- Frequency Jittering Function for Improved EMI Performance

- Burst Mode Operation for Improved Light-Load Efficiency and Reduced Standby Power

- Input and Output Over/Under-Voltage Protection

- Built-in Synchronous Slope Compensation

- Low Startup Current, Low Operating Current

- Built-in Leading-Edge Blanking (LEB) Function

- Built-in Power Limiting and Current Limiting (LPS) Function

- Built-in CS Short Circuit Protection (CSSP) Function

- Cycle-by-Cycle Current Limiting (VCS_LIM)

- VDD Voltage Clamp (VDD_CLAMP), VDD Over-Voltage Protection (VDD_OVP), Under-Voltage Lockout (UVLO)

- Secondary-Side Output Diode Short Circuit Protection (SSSP)

- Over-Temperature Protection (OTP)

- HSOP-7 Package

Applications

- QC, PD Fast Chargers

- Power Adapters for PDAs, Digital Cameras, Camcorders

- Set-Top Box Power Supplies

- Open-Frame Switching Power Supplies

- PC Auxiliary Power Supplies