Overview
The UC2854BDWTRG4, produced by Texas Instruments, is an advanced high power factor preregulator controller. It is a pin-compatible, enhanced version of the UC2854, designed to provide active power factor correction for power systems. This controller achieves near-unity power factor by shaping the AC input line current waveform to correspond to the AC input line voltage, utilizing average current mode control. This approach maintains stable, low-distortion sinusoidal line current without the need for slope compensation.
Key Specifications
| Parameter | Typical Value | Maximum Value | Unit |
|---|---|---|---|
| Supply Voltage (VCC) | 18 V | 22 V | V |
| VCC Turn-on Threshold | 10.5 V | - | V |
| VCC UVLO Hysteresis | 0.5 V | - | V |
| Supply Current (OFF) | 400 µA | - | µA |
| Supply Current (ON) | 12 mA | 18 mA | mA |
| Current Amplifier Bandwidth | 5 MHz | - | MHz |
| Current Amplifier Offset Voltage | 0 mV, -4 mV | - | mV |
| MULTOUT Voltage (High) | 5 V | - | V |
| IAC Voltage | 0.5 V | - | V |
| Junction Temperature | -55°C to 150°C | - | °C |
Key Features
- Limits line current distortion to less than 3%.
- World-wide operation without switches.
- Accurate power limiting.
- Fixed-frequency average current-mode control.
- High bandwidth (5 MHz), low-offset current amplifier.
- Integrated current- and voltage-amplifier output clamps.
- Multiplier improvements: linearity, 500 mV VAC offset, 0 V to 5 V multout common-mode range.
- VREF GOOD comparator and faster, improved accuracy ENABLE comparator.
- UVLO options (16 V/10 V or 10.5 V/10 V).
- Lower startup supply current (250 µA typical).
- Enhanced multiply/divide circuit and improved common mode input range of the multiplier output/current amplifier input.
Applications
The UC2854BDWTRG4 is designed for use in power systems that require active power factor correction, such as:
- Switch-mode power supplies.
- High-power DC-DC converters.
- Avionics applications requiring 400 Hz input.
- Offline power supplies and preregulators.
- Systems needing high power factor and low line current distortion.
Q & A
- What is the primary function of the UC2854BDWTRG4?
The UC2854BDWTRG4 is designed to provide active power factor correction for power systems, achieving near-unity power factor by shaping the AC input line current waveform.
- What is the typical supply voltage for the UC2854BDWTRG4?
The typical supply voltage (VCC) is 18 V, with a maximum of 22 V.
- What is the turn-on threshold for the VCC?
The VCC turn-on threshold is typically 10.5 V.
- What is the bandwidth of the current amplifier?
The current amplifier bandwidth is typically 5 MHz.
- What is the maximum current distortion achieved by the UC2854BDWTRG4?
The line current distortion is limited to less than 3%.
- What are the UVLO options available for the UC2854BDWTRG4?
The UVLO options are 16 V/10 V or 10.5 V/10 V.
- What is the typical startup supply current?
The typical startup supply current is 250 µA.
- What are the key improvements in the multiplier circuitry of the UC2854BDWTRG4?
The improvements include linearity, a 500 mV VAC offset, and a 0 V to 5 V multout common-mode range.
- What is the role of the VREF GOOD comparator?
The VREF GOOD comparator ensures that the MOSFET driver output remains low if the supply of the 7.5 V reference is not yet up.
- What are the typical applications of the UC2854BDWTRG4?
Typical applications include switch-mode power supplies, high-power DC-DC converters, avionics applications, and offline power supplies.
