CS3842B

Features:

`Very low Start Up Current (300A typ)
`Optimized Off-line Control
`Internally Trimmed, Temperature Compensated Oscillator
` Maximum Duty-cycle Clamp
`VREF stabilization before Output Enable
`Pulse-by-pulse Current Limiting
`Improved Undervoltage Lockout
`Double Pulse Suppression
`1% Trimmed Bandgap Reference
`High Current Totem Pole Output


Specifications

Supply Voltage (ICC<30mA)...............................................................................................Self Limiting
Supply Voltage (Low Impedance Source).......................................................................................30V
Output Current .............................................................................................................................±1A
Output Energy (Capacitive Load) ...................................................................................................5J
Analog Inputs (VFB, Sense) ............................................................................................-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 CS384XB provides all the necessary features to implement off-line fixed frequency current-mode control with a minimum number of external components. The family has been optimized for very low start up current (300A, typ).

The CS384XB family incorporates a precision temperature-controlled oscillator with an internally trimmed discharge current to minimize variations in frequency. A precision duty-cycle clamp eliminates the need for an external oscillator when a 50% duty-cycle is used. Duty-cycles of almost 100% arepossible. On board logic ensures that VREF is stabilized before the output stage is enabled. Ion-implant resistors provide tighter control of undervoltage lockout.

CS3842B Other features include pulse-by-pulse current limiting, and a high-current totem pole output for driving capacitive loads, such as the gate of a power MOSFET. The output is LOW in the off state, consistent with N-channel devices.

These ICs CS3842B are available in 8 and 14 lead surface mount (SO) and 8 lead PDIP packages.