CX7508

GENERAL DESCRIPTION

CX7508 is a high performance offline PWM power switch for low power AC/DC charger and adapter applications.It operates in primary-side sensing and regulation.Consequently, opto-coupler and

TL431 could be eliminated. High Precision Constant Voltage (CV) and Constant Current (CC) control are integrated as shown in the figure below. In CC control, the current and output power setting

can be adjusted externally by the sense resistor Rs at CS pin. In CV control, multi-mode operations are utilized to achieve high performance and high efficiency. In addition, good load regulation is

achieved by the built-in Cable Drop Compensation. Device operates in PFM in CC mode as well at large load condition and it operates in PWM with frequency reduction at light/medium load. The chip consumes very low operation current, it can achieve less than 75mW standby power.

CX7508 offers comprehensive protection coverage with auto-recovery features including Cycle-by-Cycle current limiting, VDD Over Voltage Protection (VDD OVP), short circuit protection, built-in leading edge blanking, VDD under voltage lockout (UVLO), OTP, etc.

High precision constant voltage (CV) and constant current (CC) can be achieved by CX7508.

CX7508 is offered in DIP7 package.

FEATURES

■ ± 5% Constant Voltage Regulation and Current Regulation at Universal AC Input

■ Primary Side Regulation (PSR) Without TL431 and Opto-coupler

■ No Need for Control Loop Compensation

■ Programmable CV and CC Regulation

■ Multi-Mode PWM/PFM Operation

■ Output Short Load Protection

■ Less than 75mW Standby Power

■ Built-in Line Voltage and Primary Winding Inductance Compensation

■ Built-in Adaptive Current Peak Regulation

■ Programmable Cable Drop Compensation

■ Audio Noise Free Operation

■ Built-in Over Temperature Protection (OTP)

■ Soft Gate Driver for Good EMI Performance

■ Built-in Leading Edge Blanking (LEB)

■ Cycle-by-Cycle Current Limiting

■ VDD Under Voltage Lockout with Hysteresis(UVLO)

■ VDD OVP & Clamp

APPLICATIONS

Low Power AC/DC offline SMPS for

■ Cell Phone Charger

■ Digital Camera Charger

■ Small Power Adapter

■ Auxiliary Power for PC, TV etc.

■ Linear Regulator/RCC Replacement

TYPICAL APPLICATION

GENERAL INFORMATION

Pin Configuration

The pin map of DIP7 package is shown asbelow.

Ordering Information

Package Dissipation Rating

Absolute Maximum Ratings

Note: Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, functional operation of the device at these or any other conditions beyond those indicated under“recommended operating conditions” is not implied. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability.

TERMINAL ASSIGNMENTS

BLOCK DIAGRAM