SMPS Controller The UC3844 is a high-performance current-mode PWM controller manufactured by STMicroelectronics. Below are the specifications, descriptions, and features based on factual information from Ic-phoenix technical data files:
### **Specifications:**
- **Input Voltage (VCC):** 8.4V to 30V (operating)
- **Start-Up Threshold:** 16V (typical)
- **Under-Voltage Lockout (UVLO):** 8.4V (turn-off) / 16V (turn-on)
- **Output Current (Peak):** ±1A (sink/source)
- **Switching Frequency:** Up to 500kHz
- **Duty Cycle Range:** 0% to 50% (adjustable)
- **Reference Voltage (VREF):** 5V (±1%)
- **Operating Temperature Range:** -25°C to +85°C (industrial)
### **Description:**
The UC3844 is a fixed-frequency pulse-width modulation (PWM) controller designed for DC-DC converter and offline power supply applications. It operates in current-mode control, providing improved loop response and simplified compensation. The device includes a trimmed oscillator, a precision reference, high-gain error amplifier, and a high-current totem-pole output for driving power MOSFETs.
### **Features:**
- **Current-Mode Control:** Ensures cycle-by-cycle current limiting.
- **Automatic Feed-Forward Compensation:** Improves line regulation.
- **Latching PWM for Cycle-by-Cycle Limiting:** Prevents multiple pulses.
- **Internal Trimmed Bandgap Reference:** 5V with ±1% accuracy.
- **Undervoltage Lockout (UVLO):** Ensures proper start-up and shutdown.
- **High-Current Totem-Pole Output:** Directly drives power MOSFETs.
- **Low Start-Up Current (<1mA):** Reduces power consumption.
- **Programmable Oscillator Frequency:** Adjustable via external components.
- **Soft-Start Capability:** Reduces inrush current.
This information is based on the manufacturer's datasheet for the UC3844 from STMicroelectronics.
