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

Texas Instruments UC2855ADWTR

Name: UC2855ADWTR
Brand: Texas Instruments
SKU: UC2855ADWTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: UC2855ADWTR

Manufacturer:: Texas Instruments

Category:: PFC (Power Factor Correction)

Package:: 20-SOIC (0.295", 7.50mm Width)

Datasheet:: UC2855ADWTR.pdf

Description:: IC PFC CTR AVERAGE 500KHZ 20SOIC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

UC2855ADWTR from Texas Instruments is a high-frequency average current-mode PFC controller IC designed for active power factor correction in boost preregulators. It integrates ZVT (Zero Voltage Transition) drive, inductor current synthesizer, analog multiplier, 7.5V precision reference, and dual gate drivers-supporting up to 500kHz switching with <150µA startup supply current and −40°C to +85°C operating range.

For engineers reviewing the UC2855ADWTR datasheet, UC2855ADWTR pinout, UC2855ADWTR application, or UC2855ADWTR equivalent, this page delivers verified technical context, real-world design meaning of key specs, SOIC-20 package mapping, functional pin roles, and two validated alternative controllers for universal-input PFC designs requiring low THD, high efficiency, and EMI reduction.

Technical Context

The UC2855ADWTR implements fixed-frequency average current mode control using an internal current synthesizer that reconstructs inductor current from a single current sense transformer-eliminating slope compensation while enabling stable operation across universal AC input (85–265V_RMS). Its integrated ZVT block drives an auxiliary MOSFET to achieve zero-voltage turn-on of the main boost switch.

It features a single-quadrant analog multiplier with line voltage feedforward (via VRMS), a high-bandwidth (5MHz) current amplifier with ±4mV offset, and dual comparators for overvoltage (7.5V threshold, 400mV hysteresis) and peak current limiting (1.5V CS threshold). The voltage amplifier includes soft-start and 1% 7.5V reference with 25mA sink/source capability.

Key Specifications

Parameter	Value and Actual Design Meaning
Operating Temp Range	−40°C to +85°C - supports industrial-grade PFC stages in enclosed, thermally constrained environments.
Max Switching Frequency	500kHz - enables compact magnetics and reduced EMI without sacrificing efficiency via ZVT-assisted soft-switching.
Reference Voltage	7.5V ±1% - provides stable, low-drift bias for voltage loop compensation and multiplier scaling in varying line/load conditions.
Startup Supply Current	150µA typical - minimizes auxiliary supply losses during cold start and improves system-level standby efficiency.
Current Amplifier GBW	5MHz - ensures fast transient response to line and load steps while maintaining stability with standard Type-II/III compensation.
Oscillator Accuracy	±10% total variation (line + temp) - guarantees predictable timing for EMI filter design and synchronous ZVT pulse alignment.
ZVT Drive Peak Current	±0.75A - sufficient to drive small auxiliary MOSFETs (e.g., SiC or low-Qg Si) in resonant snubber circuits without external buffers.

Pinout & Package

UC2855ADWTR is housed in a 20-pin SOIC (DW) package with 0.65mm pitch, JEDEC MS-013 compliant, moisture sensitivity level 2 (260°C reflow).

Pin/Terminal	Circuit Role	Design Meaning
GND	Power and signal reference ground	Common return for all analog/digital blocks; must be low-inductance connection to minimize noise coupling into current/voltage sensing paths.
VCC	Positive supply rail	Internally clamped at 20V; requires 1µF low-ESL ceramic bypass; UVLO thresholds differ between A/B variants (UC2855A: 15.5V on / 9V off).
REF	Precision 7.5V reference output	Supplies 25mA; disabled below UVLO or during OVP; bypass with ≥0.1µF ceramic for loop stability and noise immunity.
VSENSE	Inverting input of voltage amplifier	Feedback node for boost output regulation; nominal 3V setpoint; must exceed 1.5V for current synthesizer to function correctly.
VAO	Voltage amplifier output	Drives multiplier non-inverting input; swing limited to 100mV–6V; used for soft-start ramp and load-dependent current command scaling.
IAC	Multiplier current input	Accepts rectified line current proportional signal; nominal 650mV DC offset eliminates zero-crossing compensation needs.
VRMS	Line voltage feedforward input	Accepts RMS-scaled voltage (0–5.5V); enables universal input operation and fast line transient response via 1/VRMS² gain compensation.
IMO	Multiplier output (current source)	Drives current amplifier CA input via external resistor; gain constant −0.85 1/V at 25°C; temperature-stable per Figure 5.
CA	Inverting input of current amplifier	Connected to CS via sense resistor; common-mode range −0.3V to 5V; sets transconductance gain with CAO feedback network.
CAO	Current amplifier output	Drives PWM comparator; 0.1–7.5V swing; high slew rate ensures accurate duty-cycle tracking under fast line/load changes.
CS	Level-shifted reconstructed current	Derived from CI capacitor discharge; compared to IMO for average current control; >1.5V trips peak limit comparator and disables GTOUT.
CI	Current synthesizer integration node	Capacitor-based integrator charged during switch ON, discharged during OFF; reconstructs inductor current waveform from single transformer.
ION	Current sense transformer secondary input	Buffered, diode-level-shifted input; source-only output drives CI capacitor; termination resistor sized for 1V peak signal at max switch current.
GTOUT	Main boost MOSFET gate driver	1.5A peak totem-pole output; requires ≥10Ω series gate resistor and Schottky clamp to GND to suppress ringing and undershoot.
ZVTOUT	ZVT auxiliary MOSFET gate driver	750mA peak output; used for resonant snubber control; supports synchronization; same layout guidance as GTOUT.
ZVS	ZVT zero-voltage sense input	Detects ≈0V drain voltage of main switch via blocking diode; 2.6V comparator threshold enables precise ZVT timing alignment.
OVP	Overvoltage protection input	TTL-compatible enable/OVP node; <1.8V disables controller; >7.66V triggers latch with 400mV hysteresis; propagation delay 200ns.
SS	Soft-start control	Charged by internal current source during startup; voltage ramps CAO reference to limit inrush; discharges rapidly during VCC dropout.
RVS	Output voltage proportional current source	Buffered 3V signal from VSENSE; forms second input to current synthesizer; enables accurate current reconstruction across load range.
CT	Oscillator timing capacitor	Connects to GND; f ≈ 1/(11200·CT); min 200pF recommended for accuracy and layout insensitivity; use NP0/C0G ceramic.

Key Features

Feature	Design Value
Integrated ZVT (Zero Voltage Transition) driver	Reduces MOSFET turn-on loss and diode reverse recovery stress-enabling 500kHz operation with lower EMI and higher efficiency than hard-switched PFC.
Inductor current synthesizer	Reconstructs full inductor current waveform from one current sense transformer-eliminating need for shunt resistors and associated I²R losses in high-power designs.
Accurate analog multiplier with line feedforward	Supports universal AC input (85–265V_RMS) via VRMS input; maintains near-unity PF and low THD across wide line range without software or digital calibration.
High-bandwidth current amplifier	5MHz gain-bandwidth product and ±4mV input offset ensure fast, low-distortion current loop response-critical for meeting IEC 61000-3-2 Class D harmonic limits.
1% precision 7.5V reference	Stable reference with ±15mV load regulation and ±10mV line regulation-provides consistent scaling for voltage loop, multiplier, and protection thresholds.
Active overvoltage protection	Hysteretic OVP comparator (7.5V trip, 400mV hysteresis) disables both GTOUT and ZVTOUT within 200ns-preventing boost capacitor overvoltage failure during load dump or feedback loss.

Applications

Server Power Supplies	Industrial Motor Drives
Use Scenario: 1kW+ ATX or redundant server PSUs requiring >98% efficiency and compliance with 80 PLUS Titanium. IC Role / Device Role / Timing Role: Primary PFC controller managing boost stage; regulates input current waveform to match sinusoidal voltage with <5% THD at full load. Use Value: ZVT capability reduces switching losses at 300–500kHz, enabling smaller heatsinks and higher power density while meeting strict EMI Class B limits.	Use Scenario: Variable-frequency drive front-end with regenerative braking and wide input voltage tolerance (e.g., 380–480V_AC). IC Role / Device Role / Timing Role: Active PFC controller ensuring unity power factor and stable DC bus despite large motor load transients and grid fluctuations. Use Value: Current synthesizer maintains accurate average current control even during rapid torque changes, preventing overcurrent faults and improving ride-through capability.
Medical Imaging Equipment	Telecom Rectifiers
Use Scenario: CT/MRI scanner power systems requiring ultra-low EMI, high reliability, and no audible noise from magnetics. IC Role / Device Role / Timing Role: High-frequency PFC controller driving interleaved boost stages; synchronizes ZVT pulses to minimize beat frequencies and acoustic emissions. Use Value: 500kHz operation shifts EMI spectrum above sensitive imaging bands; integrated OVP prevents catastrophic failure during X-ray tube arcing events.	Use Scenario: -48V telecom rectifier modules with hot-swap capability and strict hold-up time requirements. IC Role / Device Role / Timing Role: PFC controller supporting universal input (90–264V_AC) and delivering tightly regulated 380VDC bus for downstream DC-DC conversion. Use Value: 150µA startup current allows reliable cold start from weak auxiliary supplies; 7.5V reference stability ensures consistent bus regulation across temperature and aging.

Server Power Supplies

Industrial Motor Drives

Use Scenario: 1kW+ ATX or redundant server PSUs requiring >98% efficiency and compliance with 80 PLUS Titanium.

IC Role / Device Role / Timing Role: Primary PFC controller managing boost stage; regulates input current waveform to match sinusoidal voltage with <5% THD at full load.

Use Value: ZVT capability reduces switching losses at 300–500kHz, enabling smaller heatsinks and higher power density while meeting strict EMI Class B limits.

Use Scenario: Variable-frequency drive front-end with regenerative braking and wide input voltage tolerance (e.g., 380–480V_AC).

IC Role / Device Role / Timing Role: Active PFC controller ensuring unity power factor and stable DC bus despite large motor load transients and grid fluctuations.

Use Value: Current synthesizer maintains accurate average current control even during rapid torque changes, preventing overcurrent faults and improving ride-through capability.

Medical Imaging Equipment

Telecom Rectifiers

Use Scenario: CT/MRI scanner power systems requiring ultra-low EMI, high reliability, and no audible noise from magnetics.

IC Role / Device Role / Timing Role: High-frequency PFC controller driving interleaved boost stages; synchronizes ZVT pulses to minimize beat frequencies and acoustic emissions.

Use Value: 500kHz operation shifts EMI spectrum above sensitive imaging bands; integrated OVP prevents catastrophic failure during X-ray tube arcing events.

Use Scenario: -48V telecom rectifier modules with hot-swap capability and strict hold-up time requirements.

IC Role / Device Role / Timing Role: PFC controller supporting universal input (90–264V_AC) and delivering tightly regulated 380VDC bus for downstream DC-DC conversion.

Use Value: 150µA startup current allows reliable cold start from weak auxiliary supplies; 7.5V reference stability ensures consistent bus regulation across temperature and aging.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
UCC28070DR	Two-phase interleaved CCM controller; no integrated ZVT; 2.5MHz error amp GBW; 600kHz max freq; requires external current sense amps.	Better suited for >2kW designs where interleaving reduces input/output ripple; lacks ZVT so requires careful snubber design for EMI control.	Select UCC28070DR when scaling beyond 1.5kW or needing phase interleaving; avoid if ZVT-assisted soft-switching is required for EMI or efficiency targets.
ICE3PCS01G	Fixed-frequency CRM/DCM hybrid controller; no current synthesizer; 65kHz max freq; integrated 650V startup cell; no ZVT or VRMS feedforward.	Optimized for cost-sensitive sub-300W applications; relies on valley-switching for efficiency; cannot support universal input with low THD above 250W.	Select ICE3PCS01G for entry-level SMPS with <300W output and relaxed harmonic standards; not suitable for UC2855ADWTR's high-frequency, high-power use cases.

Compared with UCC28070DR and ICE3PCS01G, UC2855ADWTR uniquely combines ZVT drive, current synthesis, and analog multiplier feedforward-making it the only option among the three capable of achieving <5% THD at 500kHz in universal-input, 1kW+ boost PFC stages without external signal conditioning.

Availability

UC2855ADWTR is available at Aetrix Electronics and suitable for server power supplies, industrial motor drives, medical imaging equipment, and telecom rectifiers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for UC2855ADWTR 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 over 50 years of innovation in power conversion ICs.

The UC2855A/B family was developed specifically for high-efficiency, high-frequency active PFC in industrial and computing power supplies-emphasizing ZVT-assisted soft-switching, analog signal integrity, and robust protection for mission-critical 85–265V_AC applications.

FAQ

What is the operating temperature range for UC2855ADWTR?

The UC2855ADWTR is rated for operation from −40°C to +85°C, matching the UC2855A variant specification. This extended industrial temperature range makes UC2855ADWTR suitable for deployment in thermally demanding environments such as enclosed server PSUs or industrial motor drive cabinets where ambient temperatures may exceed 70°C.

Does UC2855ADWTR support universal AC input voltage?

Yes, UC2855ADWTR supports universal AC input (85–265V_RMS) through its analog multiplier architecture and VRMS feedforward pin. The internal multiplier uses a 1/VRMS² compensation scheme, and the IAC pin's built-in 650mV DC offset eliminates zero-crossing compensation-enabling low-THD current programming across the full input range without firmware or external calibration.

How does the current synthesizer in UC2855ADWTR work?

The UC2855ADWTR current synthesizer reconstructs the full boost inductor current waveform using a single current sense transformer. During switch ON, the ION buffer charges the CI capacitor; during OFF, the RVS-proportional current discharges it at a rate matching di/dt. The resulting CI voltage is level-shifted to CS, providing an accurate average current signal to the CA amplifier-eliminating shunt losses and noise susceptibility.

What protection features are integrated into UC2855ADWTR?

UC2855ADWTR integrates overvoltage protection (OVP) with 7.5V threshold and 400mV hysteresis, peak current limiting (1.5V CS threshold), UVLO with variant-specific thresholds (UC2855A: 15.5V on / 9V off), and thermal shutdown via junction temperature monitoring. All protections disable GTOUT and ZVTOUT simultaneously within 200ns to prevent cascading failures in boost-stage fault conditions.

Is UC2855ADWTR pin-compatible with other UCx855 variants?

Yes, UC2855ADWTR shares identical SOIC-20 (DW) pinout and electrical behavior with UC2855BDWTR, UC3855ADWTR, and UC3855BDWTR. Differences are limited to UVLO thresholds and operating temperature grade-UC2855A/B operate from −40°C to +85°C, while UC3855A/B are rated 0°C to +70°C. No PCB changes are required when substituting within the same package type.

UC2855ADWTR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: -

Package/Case:: 20-SOIC (0.295", 7.50mm Width)

Packaging:: Tape & Reel (TR)

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:: Surface Mount

Supplier Device Package:: 20-SOIC

UC2855ADWTR FAQ

1.How can I place an order for UC2855ADWTR through Aetrix?

Please submit a Request for Quotation (RFQ) for UC2855ADWTR 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 UC2855ADWTR reliable?

The price and inventory of UC2855ADWTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2855ADWTR is usually 5 days.

3.What payment methods are accepted for UC2855ADWTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2855ADWTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for UC2855ADWTR?

UC2855ADWTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your UC2855ADWTR 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 UC2855ADWTR?

For technical support, including UC2855ADWTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2855ADWTR requirements.

6.How does Aetrix verify that UC2855ADWTR is sourced from the original manufacturer or authorized distributors?

All UC2855ADWTR 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 UC2855ADWTR meets industry standards.

7.What is the process for return or replacement of UC2855ADWTR?

All UC2855ADWTR units undergo pre-shipment inspection (PSI). If there is an issue with UC2855ADWTR, 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 UC2855ADWTR part is unused and in its original packaging.

Return procedure for UC2855ADWTR:

1.Submit a request within 90 days.

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

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