Overview
The UC3854BN is an enhanced bipolar Continuous Conduction Mode (CCM) Power Factor Correction (PFC) controller produced by Texas Instruments. This component is designed to provide all the necessary functions for active power factor corrected preregulators, ensuring near-unity power factor by shaping the AC input line current waveform to correspond to the AC input line voltage. The UC3854BN uses average current-mode control, which maintains stable, low distortion sinusoidal line current without the need for slope compensation, unlike peak current-mode control.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Package | PDIP (N) | - |
| Pins | 16 | - |
| Operating Temperature Range | 0°C to 70°C | °C |
| UVLO Thresholds | 10.5 V / 10 V | V |
| Start-Up Supply Current | 300 µA (typical) | µA |
| Oscillator Frequency | 85 kHz to 115 kHz | kHz |
| Current Amplifier Bandwidth | 5 MHz (typical) | MHz |
| Voltage Amplifier Offset Voltage | -8 mV to 8 mV | mV |
| VREF Voltage | 7.5 V (1% accuracy) | V |
Key Features
- Controls Boost PWM to Near-Unity Power Factor
- Limits Line Current Distortion to <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 AC Offset (Eliminates External Resistor)
- VREF GOOD Comparator and Faster, Improved Accuracy ENABLE Comparator
- UVLO Options (16 V/10 V or 10.5 V/10 V)
- Low Startup Supply Current (300 µA typical)
Applications
The UC3854BN is generally applicable to the control of AC-DC power supplies that require Active Power Factor Correction off Universal AC lines. It is particularly useful in applications that need to meet Class D equipment input current harmonics standards per EN61000-3-2, which applies to equipment with rated powers higher than 75 W. Typical applications include high-power factor preregulators, boost converters operating in continuous mode, and power supplies that require minimal line-current distortion and high efficiency.
Q & A
- What is the primary function of the UC3854BN?
The UC3854BN is designed to provide active power factor correction for AC-DC power supplies, ensuring near-unity power factor and low line current distortion.
- What type of control mode does the UC3854BN use?
The UC3854BN uses average current-mode control to maintain stable, low distortion sinusoidal line current.
- What are the UVLO threshold options for the UC3854BN?
The UC3854BN offers UVLO threshold options of 10.5 V / 10 V.
- What is the typical start-up supply current for the UC3854BN?
The typical start-up supply current for the UC3854BN is 300 µA.
- What is the bandwidth of the current amplifier in the UC3854BN?
The bandwidth of the current amplifier is 5 MHz typical.
- Does the UC3854BN require external slope compensation?
No, the UC3854BN does not require external slope compensation due to its average current-mode control.
- What standards does the UC3854BN help meet in terms of input current harmonics?
The UC3854BN helps meet Class D equipment input current harmonics standards per EN61000-3-2.
- What is the operating temperature range for the UC3854BN?
The operating temperature range for the UC3854BN is 0°C to 70°C.
- What type of package is the UC3854BN available in?
The UC3854BN is available in a 16-pin PDIP (N) package among others.
- What is the purpose of the VREF GOOD comparator in the UC3854BN?
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.
