Current Mode PWM Controller The UC3845AJ is a high-performance current-mode PWM controller manufactured by Texas Instruments (TI).
### **Specifications:**
- **Topology:** Current-mode PWM controller
- **Input Voltage (VCC):** 8V to 30V (operating range)
- **Start-up Voltage:** Typically 8.4V (UVLO turn-on)
- **Shutdown Voltage:** Typically 7.6V (UVLO turn-off)
- **Output Drive Current:** ±200mA (peak)
- **Switching Frequency:** Up to 500kHz (adjustable with external components)
- **Duty Cycle Range:** 0% to 100%
- **Error Amplifier Bandwidth:** 1MHz (typical)
- **Current Sense Comparator Response Time:** 100ns (typical)
- **Operating Temperature Range:** -40°C to +85°C
- **Package:** 8-Pin PDIP (Plastic Dual In-Line Package)
### **Descriptions:**
The UC3845AJ is designed for DC-DC converter applications, providing precise control of switching power supplies. It features a fixed-frequency current-mode architecture, improving loop response and simplifying compensation. The device includes an internal oscillator, error amplifier, current sensing comparator, and a totem-pole output stage for driving power MOSFETs.
### **Features:**
- **Current-Mode Operation:** Enhances line and load regulation.
- **Automatic Feed-Forward Compensation:** Simplifies feedback loop design.
- **Undervoltage Lockout (UVLO):** Ensures proper start-up and shutdown.
- **Pulse-by-Pulse Current Limiting:** Provides cycle-by-cycle protection.
- **Internal Trimmed Bandgap Reference:** 5V ±1% accuracy.
- **Latching PWM for Single Pulse per Period:** Prevents multiple pulses.
- **High-Current Totem-Pole Output:** Directly drives power MOSFETs.
- **Low Start-up and Operating Current:** Improves efficiency.
The UC3845AJ is commonly used in offline and DC-DC converters, battery chargers, and power supply applications.
