Summary:
CX7509X is a current mode PWM control chip with built-in high-voltage power MOSFET. It is applied to schemes with power below 22W, and operates at a fixed switching frequency in PWM mode. This frequency is precisely set internally. During no-load or light load, the working frequency is adjusted internally by the IC, and the chip can work in green mode to reduce losses during light load and improve the overall work efficiency.
CX7509X only requires a small amount of current during startup and operation, and a large resistor can be used in the startup circuit to further reduce power consumption during standby. The chip is equipped with a slope compensation circuit, which avoids the occurrence of subharmonic oscillation and improves the stability of the system when the circuit operates at a high duty cycle. The built-in leading edge blanking time eliminates the impact of diode reverse recovery current in the buffer network on the circuit.
CX7509X adopts jitter technology, which can effectively improve the EMI performance of the system. The frequency hopping of the system is set above audio (22KHz), which can avoid system noise during operation. Built-in multiple protections, including cycle by cycle current limiting protection (OCP), overvoltage protection (VDD OVP), VDD overvoltage clamping, undervoltage protection (UVLO), over temperature protection (OTP) etc. The EMI characteristics of the system can be better improved through the internal soft drive structure.
Characteristic:
Standby power consumption less than 75mW at full voltage range (90Vac-265Vac) input
Built in soft start to reduce stress on Vds on MOSFETs
Frequency jitter function to improve EMI performance
Frequency hopping mode improves light load efficiency and reduces standby power consumption
Fixed 65KHz switching frequency
Built in synchronous slope compensation
Low starting current, low working current
Built in Leading Edge Blanking (LEB) function
Built in overload protection (OLP)
Cycle by cycle current limiting protection (OCP)
VDD overvoltage protection, undervoltage protection (UVLO), VDD voltage clamping
Secondary output diode short circuit protection
Over temperature protection (OTP)
Package SOP-8L
Application:
Charger
Suitable for PDA, digital camera, camera power adapter
Set-top box power supply
Open frame switching power supply
Personal computer auxiliary power supply