UC3843 - SMD / SMT SMD-8 Current Mode PWM Controller

The UC3843 is a high-performance current-mode PWM controller designed for off-line and DC-DC converter applications. Housed in a compact SMD-8 (SOIC-8) package, it offers fast response, high efficiency, and precise regulation, making it ideal for switch-mode power supplies (SMPS), LED drivers, and isolated power conversion systems.

Key Features & Benefits:

• Current-Mode Control: Provides superior line and load regulation with inherent cycle-by-cycle current limiting.

• High-Speed Operation: Fixed operating frequency up to 500 kHz (typically used around 100 kHz).

• Undervoltage Lockout (UVLO): Optimized for low start-up current and safe power-up behavior.

• Fast Transient Response: Suitable for dynamic load conditions.

• SMD-8 Package: Surface-mount design supports high-density, automated PCB assembly.

Specifications:

• Function: Current Mode PWM Controller

• Package Type: SMD-8 / SOIC-8 (Surface-Mount)

• Operating Voltage Range: 8.5V to 30V

• Output Voltage Swing: 0V to ~V_CC

• Oscillator Frequency: Up to 500 kHz

• Start-Up Current: < 1 mA

• Operating Supply Current: ~11 mA

• UVLO Threshold:
   – Turn-on: ~8.5V
   – Turn-off: ~7.6V

• Reference Voltage: 5V ±1% (Precision internal reference)

• Output Drive Current: ±1A (typical)

• RoHS Compliant: Yes

Applications:

• Off-line switch-mode power supplies (SMPS)

• DC-DC converters

• Battery chargers

• LED drivers

• Industrial control power modules

• Flyback and forward converter topologies