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 UC3843 series of control integrated circuits provide the features that are necessary to implement off-line or DC-to-DC fixed-frequency current-mode control schemes, with a minimum number of external components. The internally implemented circuits include an under voltage lockout(UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator that also provides current-limit control, and totem-pole output stage that is designed to source or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the off state.

Optimized for off-line and DC-to-DC converters
Low start-up current (< 1 mA)
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
Error amplifier with low output resistance

Flyback Controllers, Texas Instruments

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