Overview

The CX7803 is a multi-mode flyback power chip with a built-in 800V high-voltage power MOSFET, designed for applications up to 27W. Under no-load, light-load, or heavy-load conditions, the chip automatically switches its operating mode and frequency, which are internally adjusted.

Under light load, the CX7803 operates in green mode to reduce losses and improve overall system efficiency.

The CX7803 requires only a very low current for startup and operation, allowing the use of a high-value resistor 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 CX7803 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, etc. The internal soft-driver structure further enhances the system's EMI characteristics.

Features

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

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

- Built-in 800V High-Voltage MOSFET

- Built-in Soft Start to Reduce Vds Stress on the MOSFET

- 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)

- Package: ESOP-7

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