The CS284XA, CS384XA provides all the necessary features to implement off−line fixed frequency current−mode control with a minimum number of external components.

The CS384XA family incorporates a new 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 greater than 50 are also possible. On board logic ensures that VREF is stabilized before the output stage is enabled. Ion implant resistors provide tighter control of undervoltage lockout.

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

The CS384XA series of current−mode control ICs are available in 8 and14 lead packages for surface mount (SO) applications as well as 8 lead PDIP packages.

Features

• Optimized for Off−line Control

• Internally Trimmed Temperature Compensated Oscillator

• Maximum Duty−Cycle Clamp

• VREF Stabilized Before Output Stage is Enabled

• Low Startup Current

• Pulse−By−Pulse Current Limiting

• Improved Undervoltage Lockout

• Double Pulse Suppression

• 1.0 Trimmed Bandgap Reference

• High Current Totem Pole Output