The UC3845 control IC provides the functions necessary to implement offline or DC-to-DC fixed frequency current mode control schemes with a minimum number of external components.
Internally implemented circuitry includes an undervoltage lockout (UVLO) characterized by a start-up current of less than 1 mA and a precision reference trimmed precisely at the error amplifier input.
Other internal circuitry includes logic to ensure latched operation, a pulse-width modulation (PWM) comparator to provide current-limit control, and a totem-pole output stage to source or sink peak currents. The output stage is low in the off state and is suitable for driving n-channel mosfets.
The UC3845 offers a variety of package options, temperature range options, maximum duty cycle options, turn-on and turn-off thresholds, and hysteresis range options.
Devices with higher turn-on or turn-off hysteresis are ideal for offline power supplies, while devices with narrower hysteresis ranges are suitable for DC-DC applications. The UC3845 series is specified for operation from -30°C to 85°C.
8572023-04-01
