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2022-09-24 23:33:15
UC1842W - Current Mode PWM Controller
The UC1842/3/4/5 family of control ICs provides the necessary functionality to implement off-line or DC to DC fixed frequency current mode control schemes with minimal external parts count. Internal implementation circuitry includes under-voltage lockout, start-up current less than 1mA, precision reference trimming at the input of the error amplifier, logic accuracy to ensure latched operation, a PWM comparator for current limit control, and a totem-pole output stage designed to source or sink high peak current. "The output stage, suitable for driving N-channel MOSFETs, is low in shutdown. The differences between members of this family are the undervoltage lockout threshold and maximum duty cycle range. The UC1842 and UC1844 have UVLO thresholds (16V) and 10V (off), ideal for offline applications. UC1843 and UC1845 have corresponding thresholds of 8.4V and 7.6V. UC1842 and UC1843 can operate with a duty cycle close to 100%. The range of zero to 50% is obtained by UC1844 and UC1845 by internal switching In addition, the blank output turns off all other clock cycles.