UC2845N

UC1842, UC2842, UC3842, UC1843, UC2843, UC3843 UC1844, UC2844, UC3844, UC1845, UC2845, UC3845 SLUS223G – APRIL 1997 – REVISED JULY 2022 UCx84x Current-Mode PWM Controllers 1 Features 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 Undervoltage 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 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 components. The internally implemented circuits include an undervoltage 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 a 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. VIN The UCx84x family offers a variety of package options, te...