CS3845B

CS3845B CS3845B Current Mode PWM Control Circuit with 50% Max Duty Cycle Description The CS3845B provides all the necessary features to implement off-line fixed frequency current-mode control with a minimum number of external components. The CS3845B incorporates a precision temperature-controlled oscillator to minimize variations in frequency. An internal toggle flip-flop, which blanks the output off every other clock cycle, ensures that the duty-cycle never exceeds 50%. The undervoltage lockout feature ensures that VREF is stabilized within specification before the output stage is enabled. The CS3845B has been optimized for lower start up current (500µA max). Other features include 1% trimmed band gap reference, pulse-by-pulse current limiting, and a high-current totem pole output for driving capacitive loads. Features s Optimized for Off-line Use s Temperature Compensated Oscillator s 50% Maximum Duty-cycle Clamp s Low Start-up Current (500µA max) s Pulse-by-pulse Current Limiting s Undervoltage Active Pull Down s Double Pulse Suppression s 1% Trimmed Bandgap Reference s High Current Totem Pole Output Absolute Maximum Ratings Supply Voltage (ICC