UC3843 Datasheet | Texas Instruments

UC1842, UC2842, UC3842, UC1843, UC2843, UC3843 UC1844, UC2844, UC3844, UC1845, UC2845, UC3845 SLUS223H - APRIL 1997 - REVISED OCTOBER 2024 UCx84x Current-Mode PWM Controllers 1 Features - Optimized for off-line and DC-to-DC converters - Low start-up current (< 1mA) - Automatic feedforward pensation - Pulse-by-pulse current limiting - Enhanced load-response characteristics - Undervoltage lockout with hysteresis - Double-pulse suppression - High-current totem-pole output - Internally trimmed bandgap reference - Up to 500kHz operation - Error amplifier with low output resistance 2 Applications - Switching regulators of any polarity - Transformer-coupled DC-DC converters 3 Description The UCx84x 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 ponents. The internally implemented circuits include an undervoltage lockout (UVLO), featuring a start-up current of less than 1mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to provide latched operation, a pulse-width modulation (PWM) parator that also provides current-limit control, and a totem-pole output stage that is designed to source or sink high-peak current. The output stage, designed for driving N-channel MOSFETs, is low when the output stage is in the off state. The UCx84x family offers a variety of package options, temperature range options, choice of maximum duty cycle, and choice of turnon and turnoff thresholds and hysteresis ranges. Devices with higher turnon or turnoff hysteresis are good choices for off-line power supplies, while the devices with a narrower hysteresis range are designed for...