CD5021,LM5021 Current-Mode PWM Controller Chip

The CD5021 off-line Pulse-width Modulation (PWM)controller contains all of the features needed toimplement highly efficient off-line single-endedflyback and forward power converters usingcurrent-mode control.The CD5021 features include an ultra-low start-upcurrent, which minimizes power losses in the highvoltage start-up network. A skip cycle modereduces power consumption with light loads forenergy conserving applications. Additional featuresinclude under-voltage lockout, cycle-by-cyclecurrent limit, hiccup mode overload protection,slope compensation, soft-start and oscillatorsynchronization capability. CD5021 has totalpropagation delays less than 100 ns and a 1 MHzcapable oscillator that is programmed with a singleresistor.

Ultra-low Startup Current (25 μA Maximum)

Current Mode Control

Skip Cycle Mode for Low Standby Power

Single Resistor Programmable Oscillator

Synchronizable Oscillator

Adjustable Soft-Start

Integrated 0.7A Peak Gate Driver

Direct Opto-Coupler Interface

Maximum Duty Cycle Limiting 80%

Slope Compensation

Cycle-by-Cycle Overcurrent Protection

Hiccup Mode for Continuous Overload Protection

Leading Edge Blanking of Current Sense Signal

Packages: VSSOP8