SMPS Controller The UC3845 is a high-performance current-mode PWM controller manufactured by ON Semiconductor. Below are its key specifications, descriptions, and features:
### **Specifications:**
- **Input Voltage (VCC):** 8V to 30V (operating), 7.6V (start-up), 30V (max)
- **Output Current (Peak):** ±1A (source/sink)
- **Switching Frequency:** Up to 500kHz
- **Duty Cycle Range:** 0% to 100% (adjustable)
- **Reference Voltage (VREF):** 5V (±1%)
- **Current Sense Threshold:** 1V (adjustable)
- **Error Amp Bandwidth:** 1MHz (typical)
- **Operating Temperature Range:** -40°C to +85°C
### **Descriptions:**
The UC3845 is a fixed-frequency pulse-width modulation (PWM) controller designed for DC-DC converter and power supply applications. It operates in current-mode control, providing improved loop response and simplified feedback compensation. The device includes an oscillator, error amplifier, current sensing comparator, and a totem-pole output driver.
### **Features:**
- **Current-Mode Control:** Enhances line and load regulation.
- **Automatic Feed-Forward Compensation:** Simplifies feedback design.
- **Latching PWM for Cycle-by-Cycle Current Limiting:** Protects against overcurrent.
- **Undervoltage Lockout (UVLO):** Ensures proper start-up and shutdown.
- **Adjustable Oscillator Frequency:** Set by external RC components.
- **High-Current Totem-Pole Output:** Directly drives power MOSFETs.
- **Low Start-Up Current (<1mA):** Reduces power consumption during start-up.
This information is based on ON Semiconductor's official datasheet for the UC3845.
