Overview
The UC3843ADTR is a fixed-frequency current-mode Pulse Width Modulation (PWM) controller produced by Texas Instruments. This integrated circuit is specifically designed for off-line and DC-to-DC converter applications, requiring a minimal number of external components. The UC3843ADTR is part of the UCx84x family, which offers a range of features necessary for implementing fixed-frequency current-mode control schemes.
The device features an internally trimmed bandgap reference, a high-gain error amplifier, and a current sensing comparator. It also includes a high-current totem-pole output stage designed to drive N-channel MOSFETs. The UC3843ADTR operates within a temperature range of 0°C to 70°C and supports frequencies up to 500 kHz.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Package | SOIC (D) | - |
| Pins | 8 | - |
| Operating Temperature Range | 0 to 70 | °C |
| DC Supply Voltage (VCC) | 12 to 25 | V |
| Output Current | ±1.0 | A |
| Output Energy (Capacitive Load per Cycle) | 5.0 | µJ |
| Error Amp Output Sink Current | 10 | mA |
| Current Sense and Voltage Feedback Inputs | -0.3 to 5.5 | V |
| Maximum Power Dissipation @TA=25°C | 0.862 | W |
| Thermal Resistance, Junction-to-Air | 145 | °C/W |
| Maximum Operating Junction Temperature | +150 | °C |
| Storage Temperature Range | -65 to +150 | °C |
| Reference Output Voltage | 4.9 to 5.1 | V |
| Oscillator Frequency | 46 to 60 | kHz |
Key Features
- Optimized for off-line and DC-to-DC converters
- Low start-up current (< 1mA)
- Automatic feedforward compensation
- Pulse-by-pulse current limiting
- Enhanced load-response characteristics
- Undervoltage lockout with hysteresis
- Double-pulse suppression
- High-current totem-pole output
- Internally trimmed bandgap reference
- Up to 500kHz operation
- Error amplifier with low output resistance
- Temperature compensated reference
- Current sensing comparator
Applications
- Wireless Base Station Power
- Telecom and Datacom Power
- Industrial Power Systems
- PC Power Supplies
- Switching regulators with any polarity
- Transformer coupled DC-to-DC converters
Q & A
- What is the operating temperature range of the UC3843ADTR?
The UC3843ADTR operates within a temperature range of 0°C to 70°C.
- What is the maximum output current of the UC3843ADTR?
The maximum output current is ±1.0 A.
- What is the typical oscillator frequency range of the UC3843ADTR?
The oscillator frequency range is typically between 46 kHz and 60 kHz.
- What are the key features of the UC3843ADTR's output stage?
The output stage is a high-current totem-pole output designed to source or sink high-peak currents, ideal for driving N-channel MOSFETs.
- What is the purpose of the undervoltage lockout (UVLO) in the UC3843ADTR?
The UVLO feature ensures the device does not operate below a certain voltage threshold (7.8V to 7.9V) and includes hysteresis for stable operation.
- What is the maximum duty cycle of the UC3843ADTR?
The UC3843ADTR supports up to 100% duty cycle.
- How is the oscillator frequency programmed in the UC3843ADTR?
The oscillator frequency is programmed by connecting a resistor (RT) to VREF and a capacitor (CT) to ground.
- What are some of the protective features of the UC3843ADTR?
The device includes cycle-by-cycle current limiting, double-pulse suppression, and input and reference under-voltage lockouts with hysteresis.
- What is the reference output voltage of the UC3843ADTR?
The reference output voltage is between 4.9V and 5.1V.
- What are the typical applications of the UC3843ADTR?
Typical applications include wireless base station power, telecom and datacom power, industrial power systems, and PC power supplies.
