1FEATURES
• QML-V Qualified, SMD 5962-86704
• Rad-Tolerant: 50 kRad (Si) TID (ELDRS Free) (1)
• Controlled Baseline
• Optimized For Off-line and DC-to-DC
Converters
• Low Start-Up Current (<1 mA)
• Automatic Feed Forward Compensation
• Pulse-by-Pulse Current Limiting
• Enhanced Load Response Characteristics
• Under-Voltage Lockout With Hysteresis
• Double Pulse Suppression
• High Current Totem Pole Output
• Internally Trimmed Bandgap Reference
• 500-kHz Operation
• Low RO Error Amp

DESCRIPTION
The UC1843 family of control devices provides the necessary features to implement off-line or dc-to-dc fixed
frequency current mode control schemes with a minimal external parts count. Internally implemented circuits
include under-voltage lockout featuring start up current less than 1 mA, a precision reference trimmed for
accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides
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 the off state. The under-voltage lockout threshold is
8.4 V and maximum duty cycle range is around 100%.