Overview
The UC3844ADTRG4 is a fixed-frequency current-mode PWM controller from Texas Instruments, designed for off-line and DC-to-DC converter applications. This integrated circuit is part of the UCx84x family and is optimized to implement fixed-frequency current-mode control schemes with a minimal number of external components. It features a low start-up current, automatic feedforward compensation, pulse-by-pulse current limiting, and enhanced load-response characteristics, making it suitable for a variety of power supply designs.
Key Specifications
| Parameter | Symbol | Conditions | Min. | Max. | Unit | |
|---|---|---|---|---|---|---|
| Supply Voltage | VCC | 30 | V | |||
| Output Current | IO | ±1 | A | |||
| Analog Input Voltage | V(ANA) | -0.3 | 6.3 | V | ||
| Error Amp Output Sink Current | ISINK (E.A) | 10 | mA | |||
| Reference Output Voltage | VREF | IREF = 1 mA, TJ = 25°C | 4.90 | 5.00 | 5.10 | V |
| Oscillation Frequency | fOSC | TJ = 25°C | 47 | 52 | 57 | kHz |
| Maximum Duty Cycle | D(MAX) | 47 | 48 | 50 | % | |
| Start-Up Current | IST | 0.45 | 1 | mA | ||
| Operating Supply Current | ICC(OPR) | Vpin3=Vpin2=ON | 14 | 17 | mA | |
| Storage Temperature Range | TSTG | -65 | 150 | °C | ||
| Operating Temperature Range | TA | 0 | 70 | °C |
Key Features
- 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 for driving N-channel MOSFETs
- Internally trimmed bandgap reference
- Operating frequency up to 500 kHz
- Error amplifier with low output resistance
Applications
- Switching regulators of any polarity
- Transformer-coupled DC-DC converters
- Off-line power supplies
- DC-DC converters
Q & A
- What is the typical operating frequency of the UC3844ADTRG4?
The typical operating frequency is 52 kHz, with a range of 47 kHz to 57 kHz.
- What is the maximum duty cycle for the UC3844ADTRG4?
The maximum duty cycle is 48% to 50%.
- What is the start-up current of the UC3844ADTRG4?
The start-up current is less than 1 mA, typically around 0.45 mA to 1 mA.
- What is the operating temperature range for the UC3844ADTRG4?
The operating temperature range is from 0°C to 70°C.
- What type of output stage does the UC3844ADTRG4 have?
The UC3844ADTRG4 has a high-current totem-pole output stage designed to source or sink high-peak current, suitable for driving N-channel MOSFETs.
- What is the purpose of the undervoltage lockout (UVLO) feature?
The UVLO feature ensures that the device does not operate below a certain voltage threshold, preventing malfunction and potential damage. It has hysteresis to avoid oscillations.
- How does the error amplifier in the UC3844ADTRG4 contribute to its performance?
The error amplifier has low output resistance, which enhances the overall control loop stability and accuracy in the power supply design.
- What are the package options available for the UC3844ADTRG4?
The UC3844ADTRG4 is available in SOIC (8-pin and 14-pin), PDIP (8-pin), and CFP (8-pin) packages.
- What is the significance of the internally trimmed bandgap reference in the UC3844ADTRG4?
The internally trimmed bandgap reference provides a precise and stable voltage reference, which is crucial for maintaining the accuracy and stability of the PWM controller.
- How does the UC3844ADTRG4 handle current sensing and limiting?
The UC3844ADTRG4 features a current sensing comparator and pulse-by-pulse current limiting, which help in controlling and protecting the power supply from overcurrent conditions.
