UC3845 current-mode controller

The UC3845 is a high-performance current-mode controller designed for use in switch-mode power supplies (SMPS). It is part of the UC384x family of controllers and is known for its ability to regulate power with high efficiency and stability. The UC3845 offers precise control over the output voltage and current, making it suitable for a variety of power supply applications, including DC-DC converters and AC-DC power supplies.

Key Features:

• Current-mode control for improved performance and stability
• Integrated high-current totem pole output stage
• Adjustable switching frequency for flexibility in design
• Built-in under-voltage lockout (UVLO) for reliable operation
• Thermal shutdown and current limiting for protection
• External compensation for optimizing performance
• Suitable for both continuous and discontinuous mode operation

Technical Specifications:

• Input Voltage Range: 8V to 30V (typical)
• Switching Frequency: Adjustable, typically 100 kHz to 500 kHz
• Output Current Capability: 1A (peak)
• Reference Voltage (Vref): 2.5V
• Current Sense Voltage: Typically 0.5V
• Thermal Shutdown: Integrated
• Package Type: Available in 8-pin DIP, SOIC, and other surface-mount packages

Applications:

• DC-DC converters (buck, boost, buck-boost)
• AC-DC power supplies
• Power factor correction circuits
• Battery chargers
• Power management systems
• Inverter circuits

Usage:

1. Connect the UC3845 to the input power supply and configure the feedback network to set the desired output voltage.
2. Use external components (inductor, capacitor, and sense resistor) to establish the switching frequency, compensation, and current sensing.
3. Adjust the external compensation network to ensure stability and optimal performance.
4. Ensure proper heat dissipation and cooling if operating at high power levels.

Caution:

• Verify the input voltage and output current ratings to avoid exceeding the device’s specifications.
• Properly design the external components to match the required performance criteria.
• Handle with care to avoid damage from electrostatic discharge (ESD) and follow recommended operating conditions.

Datasheet:
For detailed technical specifications, refer to the UC3845 Datasheet.