Professional IC Distribution & Technical Solutions

The UC3843B is a high-performance current-mode PWM controller manufactured by Motorola (MOT).

Specifications:

• Topology: Current-mode PWM control
• Operating Frequency: Up to 500 kHz
• Output Drive: Single-ended output (suitable for driving MOSFETs)
• Duty Cycle Range: 0% to 100%
• Supply Voltage (VCC): 8V to 30V
• Start-up Current: Typically 0.5 mA
• Under-Voltage Lockout (UVLO): 8.4V (on) / 7.6V (off)
• Peak Output Current: ±1A (sink/source)
• Error Amplifier Bandwidth: 1 MHz
• Reference Voltage (VREF): 5V (±1%)
• Operating Temperature Range: -40°C to +85°C

Descriptions:

The UC3843B is designed for DC-DC converter applications, providing precise control for power supplies. It features a trimmed oscillator for accurate frequency control, a temperature-compensated reference, and a high-gain error amplifier.

Features:

• Current-Mode Operation: Improves loop response and simplifies compensation.
• Automatic Feed-Forward Compensation: Enhances line regulation.
• Latching PWM: Ensures single-pulse operation per cycle.
• Undervoltage Lockout (UVLO): Ensures reliable start-up and shutdown.
• High-Current Totem Pole Output: Directly drives power MOSFETs.
• Cycle-by-Cycle Current Limiting: Protects against overloads.
• Low Start-up and Operating Current: Improves efficiency.

This IC is commonly used in flyback, forward, and boost converters.