CS3845B

Features:

` Optimized for Off-line Use
` Temperature Compensated Oscillator
` 50% Maximum Duty-cycle Clamp
` Low Start-up Current (500A max)
` Pulse-by-pulse Current Limiting
` Undervoltage Active Pull Down
` Double Pulse Suppression
` 1% Trimmed Bandgap Reference
` High Current Totem Pole Output


Pinout




Specifications

Supply Voltage (ICC<30mA).........................................................Self Limiting
Supply Voltage (Low Impedance Source)..................................................30V
Output Current ......................................................................................±1A
Output Energy (Capacitive Load) ..............................................................5J
Analog Inputs (VFB, VSENSE).....................................................-0.3V to 5.5V
Error Amp Output Sink Current............................................................ ..10mA
Lead Temperature Soldering
    Wave Solder (through hole styles only) ..............  10 sec. max, 260°C peak
    Reflow (SMD styles only) ...............60 sec. max above 183°C, 230°C peak


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 (500A max).

CS3845B Other features include 1% trimmed band gap reference, pulse-by-pulse current limiting, and a high-current totem pole output for driving capacitive loads.