UC2842BN

UC2842B/3B/4B/5B ® UC3842B/3B/4B/5B HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER . TRIMMED OSCILLATOR FOR PRECISE FREQUENCY CONTROL . OSCILLATOR FREQUENCY GUARANTEED AT 250kHz . CURRENT MODE OPERATION TO 500kHz . AUTOMATIC FEED FORWARD COMPENSA- TION . LATCHING PWM FOR CYCLE-BY-CYCLE CURRENT LIMITING . INTERNALLY TRIMMED REFERENCE WITH UNDERVOLTAGE LOCKOUT . HIGH CURRENT TOTEM POLE OUTPUT . UNDERVOLTAGE LOCKOUT WITH HYSTER- ESIS . LOW START-UP AND OPERATING CURRENT Minidip SO8 comparatorwhich alsoprovidescurrent limit control, and a totem pole output stage designed to source or sink high peakcurrent. The outputstage, suitable for driving N-Channel MOSFETs, is low in the offstate. DESCRIPTION Differences between members of this family are the under-voltagelockout thresholds and maximum duty TheUC384xB family ofcontrolICs providesthe nec- cycle ranges. The UC3842B and UC3844B have essary features to implement off-line or DC to DC UVLO thresholds of 16V (on) and 10V (off), ideally fixed frequency current mode control schemes wwwwit.DhataSheet4Us.cuomitedoff-lineapplicationsThecorrespondingthresh- a minimal external parts count. Internally imple- oldsforthe UC3843BandUC3845Bare8.5 V and7.9 mented circuits include a trimmed oscillator for pre- V. The UC3842B and UC3843B can operate to duty cise DUTY CYCLE CONTROL under voltage lock- cycles approaching 100%. A range of the zero to < outfeaturingstart-up current less than0.5mA,a pre- 50 % is obtained by the UC3844B a...