UC3843

The UC3843 is a fixed frequency current-mode Pulse Width Modulation (PWM) controller, optimized for Off Line and DC-to-DC converter applications. It offers minimal external component requirements, featuring a trimmed oscillator for precise duty cycle control, a temperature-compensated reference, a high-gain error amplifier, a current-sensing comparator, and a high-current totem pole output suitable for driving a power MOSFET. The device also includes protective features such as input and reference under-voltage lockouts, each with hysteresis, and cycle-by-cycle current limiting. Key Features:

• Fixed frequency current-mode PWM control
• Precise duty cycle control with trimmed oscillator
• Temperature-compensated reference
• High-gain error amplifier
• High-current totem pole output
• Input and reference under-voltage lockouts with hysteresis
• Cycle-by-cycle current limiting
• Suitable for driving power MOSFETs
• Operates up to 500 kHz

Technical Specifications:

• Operating Temperature Range: 0°C to +70°C
• Supply Voltage (VCC): 12V to 25V
• Output Current: ±1.0A
• Oscillator Frequency: 47 kHz to 60 kHz (typical)
• Reference Voltage: 4.9V to 5.1V
• Output Voltage Rise Time: 150 ns
• Output Voltage Fall Time: 150 ns

Applications:

• Wireless base station power
• Telecom and datacom power supplies
• Industrial power systems
• PC power supplies

Usage: The UC3843 is designed for high-performance power management in applications requiring stable and reliable PWM control. It is ideal for use in power supplies and converters that operate at fixed frequencies and require robust protection features. Caution: Ensure that the supply voltage and output currents are within specified limits to avoid damage to the device. Proper thermal management is required to maintain operational integrity. Datasheet: For detailed specifications, application information, and circuit design guidance, refer to the UC3843 datasheet.