The isolated-flyback power supply controller provides Constant-Voltage (CV) and Constant-Current (CC) output regulation to improve transient response to large load steps. Primary-Side Regulation (PSR) eliminates the need for an Optocoupler.

The Texas Instruments UC3843A family of control devices is a pin-for-pin compatible improved version of theUCx84x family. Providing the necessary features to control current-mode or switched-mode power supplies, this family of devices has many improved features: start-up current is less than 0.5 mA, oscillator discharge is trimmed to 8.3 mA, and during UVLO, the output stage can sink at least 10mA at less than 1.2 V for VCC over 5 V.

Optimized for Off-Line and DC-DC Converters
Low Start-Up Current (< 0.5 mA)
Trimmed Oscillator Discharge Current
Automatic Feedforward Compensation
Pulse-by-Pulse Current Limiting
Enhanced Load Response Characteristics
Under voltage Lockout With Hysteresis
Double Pulse Suppression
High-Current Totem Pole Output
Internally-Trimmed Bandgap Reference
Up to 500-kHz Operation

Flyback Controllers, Texas Instruments

Current-Mode and Voltage-Mode PWM Controller
Primary-Side Regulation
Peak Power Mode
Low Power