Overview
The UC3845D8TRG4 is a current-mode PWM controller from Texas Instruments, part of the UCx84x family. This integrated circuit is designed to implement off-line or DC-to-DC fixed-frequency current-mode control schemes with a minimal number of external components. It features a low start-up current of less than 1 mA, automatic feedforward compensation, pulse-by-pulse current limiting, and enhanced load-response characteristics. The device includes an undervoltage lockout (UVLO) with hysteresis, double-pulse suppression, and a high-current totem-pole output stage suitable for driving N-channel MOSFETs.
Key Specifications
| Parameter | Min | Max | Unit | |
|---|---|---|---|---|
| VCC (Low impedance source) | - | - | 30 | V |
| IVCC (Self Limiting) | - | - | 30 mA | mA |
| VFB and VISENSE (Analog input voltage) | -0.3 | - | 6.3 | V |
| IOUTPUT (Output drive current) | - | - | ±1 A | A |
| ICOMP (Error amplifier output sink current) | - | - | 10 mA | mA |
| TJ (Junction temperature) | - | - | 150 °C | °C |
| Tstg (Storage temperature) | -65 | - | 150 °C | °C |
| fOSC (Oscillator frequency) | 100 kHz | - | 500 kHz | kHz |
| TA (Operating free-air temperature) | 0 °C | - | 70 °C | °C |
| VREF (Reference voltage) | 4.9 V | 5 V | 5.1 V | V |
Key Features
- Optimized for off-line and DC-to-DC converters
- Low start-up current (< 1 mA)
- Automatic feedforward compensation
- Pulse-by-pulse current limiting
- Enhanced load-response characteristics
- Undervoltage lockout with hysteresis
- Double-pulse suppression
- High-current totem-pole output stage
- Internally trimmed bandgap reference
- Up to 500-kHz operation
- Error amplifier with low output resistance
Applications
- Switching regulators of any polarity
- Transformer-coupled DC-DC converters
Q & A
- What is the operating temperature range of the UC3845D8TRG4?
The UC3845D8TRG4 operates from 0°C to 70°C.
- What is the maximum oscillator frequency of the UC3845D8TRG4?
The maximum oscillator frequency is up to 500 kHz.
- What is the start-up current of the UC3845D8TRG4?
The start-up current is less than 1 mA.
- Does the UC3845D8TRG4 have undervoltage lockout (UVLO) with hysteresis?
- What type of output stage does the UC3845D8TRG4 have?
The device features a high-current totem-pole output stage.
- What is the reference voltage of the UC3845D8TRG4?
The reference voltage is 4.9 V to 5.1 V.
- Can the UC3845D8TRG4 be used in transformer-coupled DC-DC converters?
- What is the maximum duty cycle for the UC3845D8TRG4?
The maximum duty cycle is up to 50% for the UC3845 models.
- Does the UC3845D8TRG4 have pulse-by-pulse current limiting?
- What is the recommended operating voltage range for VCC?
The recommended operating voltage range for VCC is up to 30 V.
