Overview
The UC3854ADWTRG4 is an advanced high power factor preregulator controller produced by Texas Instruments. It is designed as a pin-compatible upgrade to the industry-standard UC3854, offering enhanced features and improved performance. This controller is specifically tailored for active power factor correction (PFC) applications, ensuring near-unity power factor by shaping the AC input line current waveform to correspond to the AC input line voltage.
The UC3854ADWTRG4 uses average current mode control, which maintains stable, low-distortion sinusoidal line current without the need for slope compensation. This device is suitable for a wide range of power supply applications requiring high efficiency and compliance with power factor regulations.
Key Specifications
| Parameter | Test Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Current (Off) | VCC = VUVLO–0.3 V | 250 | 400 | µA | |
| Supply Current (On) | 12 | 18 | 3.5 | mA | |
| VCC Turn-On Threshold Voltage | 15.0 | 16.0 | 17.5 | V | |
| VCC Turn-Off Threshold Voltage | 9 | 10 | 12 | V | |
| VCC Hysteresis | 5 | 6 | 7 | V | |
| Current Amplifier Input Offset Voltage | VCM = 0 V, TA = 25°C | –4 | 0 | 3 | mV |
| Current Amplifier Gain Bandwidth Product | fIN = 100 kHz, 10 mVp-p | 3 | 5 | MHz | |
| Reference Voltage | IREF = 0 mA, TA = 25°C | 7.4 | 7.5 | 7.6 | V |
| Reference Voltage Load Regulation | 1 mA ≤ IREF ≤ 10 mA | 0 | 8 | 20 | mV |
Key Features
- Near-Unity Power Factor: Achieves near-unity power factor by shaping the AC input line current waveform to correspond to the AC input line voltage.
- Average Current Mode Control: Maintains stable, low-distortion sinusoidal line current without the need for slope compensation.
- High Bandwidth Current Amplifier: Offers a wide bandwidth of 5 MHz, essential for high-frequency applications such as 400 Hz avionics.
- Improved Multiplier and Divider Circuitry: Enhancements include linearity improvements, a 500 mV VAC offset, and a 0 V to 5 V multout common-mode range.
- Low Offset Voltage: The current amplifier has an improved input offset voltage from ±4 mV to 0 V to ±3 mV, eliminating the need for external offset cancellation networks.
- UVLO Options: Provides under-voltage lockout (UVLO) threshold options of 16 V/10 V and 10.5 V/10 V, allowing startup from an auxiliary 12-V supply.
- Lower Startup Supply Current: Reduces power requirements with a startup supply current of 250 µA typical.
- VREF GOOD Comparator: Ensures the MOSFET driver output remains low until the 7.5 V reference supply is stable.
- Integrated Current- and Voltage-Amplifier Output Clamps: Reduces the external component count while improving performance.
Applications
- Active Power Factor Correction (PFC): Ideal for PFC preregulators in high-power applications requiring compliance with power factor regulations.
- Power Supplies: Suitable for a wide range of power supply designs, including offline and online power supplies.
- Avionics and Aerospace: Essential for 400 Hz input avionics applications due to its high bandwidth and low distortion characteristics.
- Industrial and Commercial Equipment: Used in various industrial and commercial equipment requiring high efficiency and reliable power management.
Q & A
- What is the primary function of the UC3854ADWTRG4?
The UC3854ADWTRG4 is designed for active power factor correction, achieving near-unity power factor by shaping the AC input line current waveform.
- What is the operating temperature range for the UC3854ADWTRG4?
The operating temperature range is 0°C to 70°C for the UC3854A and –40°C to 85°C for the UC2854A and UC2854B.
- What are the UVLO threshold options available for the UC3854ADWTRG4?
The UVLO threshold options are 16 V/10 V and 10.5 V/10 V, allowing startup from an auxiliary 12-V supply.
- How does the UC3854ADWTRG4 improve upon its predecessor, the UC3854?
The UC3854ADWTRG4 offers improvements such as a wider bandwidth current amplifier, lower offset voltage, and enhanced multiplier and divider circuitry.
- What is the significance of the VREF GOOD comparator in the UC3854ADWTRG4?
The VREF GOOD comparator ensures that the MOSFET driver output remains low until the 7.5 V reference supply is stable, eliminating the need for external Schottky diodes.
- What are the package options available for the UC3854ADWTRG4?
The device is available in 16-pin N (PDIP), DW (SOIC Wide), and J (CDIP) packages, as well as a 20-pin Q (PLCC) package.
- How does the UC3854ADWTRG4 reduce external component count?
The device integrates current- and voltage-amplifier output clamps and has improved amplifier current sinking capability, reducing the need for external components.
- What is the typical startup supply current for the UC3854ADWTRG4?
The typical startup supply current is 250 µA, substantially reducing power requirements.
- Is the UC3854ADWTRG4 suitable for high-frequency applications?
Yes, it is suitable for high-frequency applications such as 400 Hz avionics due to its high bandwidth and low distortion characteristics.
- What are the key applications of the UC3854ADWTRG4?
The key applications include active power factor correction, power supplies, avionics, and industrial and commercial equipment.
