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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > PFC (Power Factor Correction)

Texas Instruments UC2855AN

Name: UC2855AN
Brand: Texas Instruments
SKU: UC2855AN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: UC2855AN

Manufacturer:: Texas Instruments

Category:: PFC (Power Factor Correction)

Package:: 20-DIP (0.300", 7.62mm)

Datasheet:: UC2855AN.pdf

Description:: IC PFC CTR AV CURR 500KHZ 20DIP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

UC2855AN from Texas Instruments is a high-frequency average current-mode PFC controller IC designed for boost-type power factor correction preregulators in AC-DC front-ends. It integrates ZVT (Zero Voltage Transition) active snubbing, an inductor current synthesizer, analog multiplier with line compensation, and dual gate drivers (GTOUT and ZVTOUT) - enabling stable near-unity power factor operation up to 500kHz with low THD and reduced EMI in industrial and telecom power supplies.

For engineers reviewing the UC2855AN datasheet, UC2855AN pinout, UC2855AN application, or UC2855AN equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions for DIP-20 layout, confirmed alternatives for PFC controller selection, and supply-chain support details specific to UC2855AN's temperature range (–40°C to +85°C) and RoHS-compliant PDIP package.

Technical Context

The UC2855AN implements fixed-frequency average current mode control using a wide-bandwidth (5MHz) current amplifier and a precision 7.5V reference (±1%) to achieve low line-current distortion without slope compensation. Its internal current synthesizer reconstructs inductor current from a single current sense transformer signal via CI/CS/ION paths, enabling accurate sensing with negligible loss.

It features a single-quadrant analog multiplier with line-voltage feedforward (VRMS input), overvoltage protection (OVP threshold 7.66V, 400mV hysteresis), UVLO with dual thresholds (UC2855A: 15.5V turn-on, 6V hysteresis), and two independent gate drivers: GTOUT (±1.5A peak, 12.8V high) for the main boost MOSFET and ZVTOUT (±0.75A peak, 12.8V high) for the auxiliary ZVT switch.

Key Specifications

Parameter	Value and Actual Design Meaning
Oscillator Frequency	160–240 kHz typical; sets practical boost switching up to 500kHz with external CT capacitor and ZVT circuitry.
Current Amplifier GBW	2.5–5 MHz; enables fast response to inductor current transients for low-distortion AC line current shaping.
Voltage Reference	7.5 V ±1% at 25°C; provides stable bias for voltage loop and multiplier, critical for output regulation accuracy.
Gate Driver Peak Current	GTOUT: ±1.5 A; ZVTOUT: ±0.75 A; sufficient to drive MOSFET gates directly with minimal external components.
OVP Threshold & Hysteresis	7.66 V with 400 mV hysteresis; prevents nuisance tripping during transient overvoltage while ensuring reliable boost output protection.
Operating Temperature	–40°C to +85°C; qualified for industrial-grade power supply environments requiring extended thermal reliability.
Startup Supply Current	150 µA typical; allows low-power auxiliary supply design and reduces standby losses in PFC stages.

Pinout & Package

UC2855AN is housed in a 20-pin plastic dual in-line package (PDIP-N), with lead finish CU NIPDAU and RoHS/Green compliance. Pin numbering follows standard DIL-20 orientation (pin 1 at top-left corner, counterclockwise).

Pin/Terminal	Circuit Role	Design Meaning
CA	Inverting input of current amplifier	Connects to compensation network; common-mode range −0.3 V to 5 V ensures robust noise immunity in high-dV/dt PFC layouts.
CAO	Current amplifier output	Drives PWM comparator; rail-to-rail swing (0.1–7.5 V) supports full-duty-cycle control across line/load variations.
CI	Current synthesizer capacitor node	Integrates buffered ION signal during switch-on and discharges proportionally to di/dt during off-time - reconstructs continuous inductor current waveform.
CS	Level-shifted current synthesizer output	Feeds reconstructed current to CA input and peak-limit comparator; >1.5 V disables GTOUT, providing cycle-by-cycle current limiting.
CT	Oscillator timing capacitor connection	Frequency set by f ≈ 1/(11200·CT); min 200 pF recommended for stability and layout insensitivity up to 500 kHz.
GND	Signal and power ground reference	All voltages referenced here; bypass capacitors must have shortest possible leads to minimize ground bounce in high-di/dt switching.
GTOUT	Main boost MOSFET gate driver output	1.5 A peak totem-pole output; requires ≥10 Ω series gate resistor and Schottky clamp to GND for overshoot/undershoot control.
IAC	Multiplier line-voltage current input	Accepts rectified AC line current; nominal 650 mV offset eliminates zero-crossing compensation resistors in universal-input designs.
IMO	Multiplier current output	Current-mode output (−205 µA typ at VRMS=1.5 V); connects to CA via resistor matching current amplifier input impedance.
ION	Current sense transformer secondary input	Buffered, level-shifted input for transformer-based sensing; source-only output drives CI capacitor during switch conduction.
OVP	Overvoltage sense and enable input	TTL-compatible; <1.8 V disables REF, oscillator, and PWM; >7.66 V triggers latch with 400 mV hysteresis for boost output fault recovery.
REF	Precision 7.5 V reference output	Supplies 25 mA max; internally short-circuit protected; disabled below UVLO; requires ≥0.1 µF ceramic bypass for stability.
RVS	Output voltage proportional current source	Provides 3 V nominal buffered signal; forms second input to current synthesizer, enabling load-independent current programming.
SS	Soft-start capacitor connection	Charged by internal current source during startup; controls duty-cycle ramp-up; rapidly discharged on VCC dropout to prevent erratic restart.
VAO	Voltage amplifier output	100 mV–6 V swing; feeds multiplier non-inverting input; <1.5 V inhibits multiplier output, preventing instability at light loads.
VCC	Positive supply input	Internally clamped to 20 V; UVLO turn-on at 15.5 V (A version), hysteresis 6 V; bypass with 1 µF low-ESL ceramic capacitor.
VRMS	Line RMS voltage feedforward input	0–5.5 V range; enables universal input (90–265 VAC) via 1/VRMS² gain scaling; 1.5 V = low line, 4.7 V = high line.
VSENSE	Voltage amplifier inverting input	Feedback node for boost output regulation; senses via resistor divider to 3 V nominal; must exceed 1.5 V for current synthesizer operation.
ZVS	ZVT zero-voltage sense input	Detects MOSFET drain voltage drop to ~0.7 V; resets ZVT latch when drain reaches zero; requires blocking diode for HV drain sensing.
ZVTOUT	ZVT auxiliary switch gate driver	750 mA peak output; drives smaller ZVT MOSFET; same layout rules as GTOUT; usable as sync output in multi-phase systems.

Key Features

Feature	Design Value
Average current mode control	Eliminates need for slope compensation and enables stable, low-THD AC line current programming across universal input ranges.
Integrated ZVT (Zero Voltage Transition)	Reduces boost diode reverse recovery and MOSFET turn-on losses, lowering EMI and improving efficiency at frequencies up to 500 kHz.
Inductor current synthesizer	Reconstructs continuous inductor current using only one current sense transformer - improves noise margin and cuts sensing losses in >300 W PFC stages.
Analog multiplier with line compensation	Uses VRMS feedforward to scale current command by 1/VRMS², enabling constant power delivery and fast line transient response in universal-input designs.
High-bandwidth current amplifier	5 MHz gain-bandwidth product and 80–110 dB open-loop gain ensure precise, high-speed current loop control for tight THD compliance.
Dual independent gate drivers	GTOUT (±1.5 A) and ZVTOUT (±0.75 A) support separate drive of main and auxiliary switches - simplifies ZVT implementation without external drivers.

Applications

Server Power Supply	Industrial Motor Drive Input Stage
Use Scenario: 1 kW+ AC-DC front-end in 1U/2U server PSUs requiring >98% efficiency and EN61000-3-2 Class A compliance. IC Role / Device Role / Timing Role: Primary PFC controller managing boost converter switching, ZVT timing, and line-current shaping via average current mode. Use Value: Enables 500 kHz operation with low EMI, reducing filter size and weight while maintaining <5% THD at full load across 90–265 VAC.	Use Scenario: Input stage of variable-frequency drive powering 3-phase induction motors in factory automation systems. IC Role / Device Role / Timing Role: High-reliability PFC regulator ensuring stable DC bus under unbalanced or distorted utility voltage conditions. Use Value: –40°C to +85°C rating and robust OVP/UVLO hysteresis support continuous operation in harsh industrial environments with wide ambient swings.
Telecom Rectifier Shelf	Medical Imaging Power System
Use Scenario: 3 kW distributed power architecture rectifier shelf feeding multiple DC-DC modules in central office equipment. IC Role / Device Role / Timing Role: Dual-gate-driver PFC controller coordinating main boost and ZVT switch timing to minimize conduction and switching losses. Use Value: Integrated current synthesizer and 5 MHz current amplifier allow precise current loop control at high power density, reducing thermal stress on passive components.	Use Scenario: High-stability power supply for CT/MRI detector subsystems demanding ultra-low ripple and rapid transient recovery. IC Role / Device Role / Timing Role: Precision PFC controller delivering tightly regulated DC bus with <0.1% output variation under dynamic load steps. Use Value: 1% 7.5 V reference and 65–80 dB voltage amplifier open-loop gain ensure consistent regulation accuracy across line, load, and temperature.

Server Power Supply

Industrial Motor Drive Input Stage

Use Scenario: 1 kW+ AC-DC front-end in 1U/2U server PSUs requiring >98% efficiency and EN61000-3-2 Class A compliance.

IC Role / Device Role / Timing Role: Primary PFC controller managing boost converter switching, ZVT timing, and line-current shaping via average current mode.

Use Value: Enables 500 kHz operation with low EMI, reducing filter size and weight while maintaining <5% THD at full load across 90–265 VAC.

Use Scenario: Input stage of variable-frequency drive powering 3-phase induction motors in factory automation systems.

IC Role / Device Role / Timing Role: High-reliability PFC regulator ensuring stable DC bus under unbalanced or distorted utility voltage conditions.

Use Value: –40°C to +85°C rating and robust OVP/UVLO hysteresis support continuous operation in harsh industrial environments with wide ambient swings.

Telecom Rectifier Shelf

Medical Imaging Power System

Use Scenario: 3 kW distributed power architecture rectifier shelf feeding multiple DC-DC modules in central office equipment.

IC Role / Device Role / Timing Role: Dual-gate-driver PFC controller coordinating main boost and ZVT switch timing to minimize conduction and switching losses.

Use Value: Integrated current synthesizer and 5 MHz current amplifier allow precise current loop control at high power density, reducing thermal stress on passive components.

Use Scenario: High-stability power supply for CT/MRI detector subsystems demanding ultra-low ripple and rapid transient recovery.

IC Role / Device Role / Timing Role: Precision PFC controller delivering tightly regulated DC bus with <0.1% output variation under dynamic load steps.

Use Value: 1% 7.5 V reference and 65–80 dB voltage amplifier open-loop gain ensure consistent regulation accuracy across line, load, and temperature.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PFC controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
UC3855AN	Same pinout and feature set, but rated for 0°C to +70°C industrial temperature range; lower UVLO turn-on (10.5 V) and reduced hysteresis (500 mV).	Suitable for cost-sensitive commercial power supplies where extended temperature operation is not required.	Select UC3855AN only if ambient operating temperature stays within 0–70°C and lower startup voltage is acceptable.
L6562A	Fixed-frequency average current-mode PFC controller with integrated 600 V startup circuit; no ZVT support; 2.5 MHz current amplifier GBW; SO-8 package.	Targets simpler, lower-cost PFC designs without soft-switching; lacks ZVTOUT and current synthesizer - requires shunt-based current sensing.	Choose L6562A for compact, non-ZVT designs below 300 W; UC2855AN remains preferred for >300 W, high-efficiency, ZVT-enabled systems.

Compared with UC3855AN, UC2855AN offers extended temperature capability and higher UVLO hysteresis for improved brownout resilience; compared with L6562A, it delivers ZVT support, current synthesis, and dual gate drivers - enabling higher power, lower EMI, and better efficiency in demanding industrial and telecom applications.

Availability

UC2855AN is available at Aetrix Electronics and suitable for industrial motor drives, telecom rectifiers, medical imaging power systems, and server PSUs requiring stable component supply with long-term lifecycle assurance.

Supply support for UC2855AN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in power conversion ICs.

The UC2855A/B family was designed specifically for high-efficiency, high-frequency active PFC in industrial and telecom AC-DC power supplies - emphasizing ZVT integration, current synthesis, and robust protection features.

FAQ

What is the operating temperature range of the UC2855AN?

The UC2855AN is specified for operation from –40°C to +85°C, making it suitable for industrial-grade power supplies exposed to wide ambient temperature variations. This extended range distinguishes it from the UC3855AN (0°C to +70°C) and supports reliable performance in demanding environments such as factory automation and outdoor telecom equipment where thermal stress is significant. The UC2855AN maintains full electrical specifications across this range.

Does the UC2855AN support Zero Voltage Transition (ZVT) operation?

Yes, the UC2855AN integrates dedicated ZVT circuitry including ZVS input, ZVTOUT gate driver, and internal logic to enable resonant soft-switching of the boost diode and main MOSFET. This reduces switching losses and EMI, allowing practical operation up to 500 kHz. The ZVTOUT driver delivers ±0.75 A peak current and supports auxiliary switch control without external drivers - a core differentiator versus basic PFC controllers like the L6562A.

How does the current synthesizer in the UC2855AN improve PFC design?

The UC2855AN's current synthesizer reconstructs the full inductor current waveform using only one current sense transformer, eliminating the need for a second sensing element or shunt resistor. By charging the CI capacitor during switch-on and discharging it proportionally to di/dt during switch-off, it achieves high signal-to-noise ratio and negligible sensing losses - especially valuable in high-power (>300 W) PFC stages where efficiency and thermal management are critical.

What are the key differences between UC2855AN and UC3855AN?

The UC2855AN and UC3855AN share identical pinout, functionality, and electrical characteristics except for temperature rating and UVLO behavior. UC2855AN operates from –40°C to +85°C and has a 15.5 V turn-on threshold with 6 V hysteresis; UC3855AN is rated 0°C to +70°C with 10.5 V turn-on and 500 mV hysteresis. Both use the same PDIP-20 package and support identical ZVT and current synthesis features.

Can the UC2855AN be used in universal input (90–265 VAC) applications?

Yes, the UC2855AN supports universal input operation via its VRMS feedforward input and analog multiplier with line compensation. With VRMS scaled to 1.5 V at low line and 4.7 V at high line, the multiplier automatically adjusts the current command by 1/VRMS² to maintain constant power delivery - enabling stable, low-THD operation across 90–265 VAC without hardware changes. This is confirmed in the device's Electrical Characteristics table and Typical Application schematic.

UC2855AN Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: -

Package/Case:: 20-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Obsolete

Mode:: Average Current

Frequency - Switching:: 500kHz

Current - Startup:: 150 µA

Voltage - Supply:: 15.5V ~ 20V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 20-PDIP

UC2855AN FAQ

1.How can I place an order for UC2855AN through Aetrix?

Please submit a Request for Quotation (RFQ) for UC2855AN on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for UC2855AN reliable?

The price and inventory of UC2855AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2855AN is usually 5 days.

3.What payment methods are accepted for UC2855AN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2855AN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for UC2855AN?

UC2855AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your UC2855AN order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for UC2855AN?

For technical support, including UC2855AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2855AN requirements.

6.How does Aetrix verify that UC2855AN is sourced from the original manufacturer or authorized distributors?

All UC2855AN products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that UC2855AN meets industry standards.

7.What is the process for return or replacement of UC2855AN?

All UC2855AN units undergo pre-shipment inspection (PSI). If there is an issue with UC2855AN, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The UC2855AN part is unused and in its original packaging.

Return procedure for UC2855AN:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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