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Texas Instruments UC2855BDWTR
- Part No.:
- UC2855BDWTR
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
UC2855BDWTR.pdf
- Description:
- IC PFC CTR AVERAGE 500KHZ 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,483
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Product details
Overview
UC2855BDWTR from Texas Instruments is a high-frequency average current-mode PFC controller IC designed for active power factor correction in boost preregulator stages. It delivers fixed-frequency control up to 500kHz, integrates ZVT (Zero Voltage Transition) drive for reduced switching losses, features a 7.5V ±1% reference, 5MHz current amplifier bandwidth, and operates across −40°C to +85°C. It targets industrial AC-DC front-end supplies requiring >95% power factor and low THD.
For engineers reviewing the UC2855BDWTR datasheet, UC2855BDWTR pinout, UC2855BDWTR application, or UC2855BDWTR equivalent, this page provides verified technical context, validated pin functions, real-world application mappings, and confirmed alternative options for high-efficiency PFC design validation and BOM optimization.
Technical Context
The UC2855BDWTR implements average current mode control using an internal current synthesizer that reconstructs inductor current from a single current sense transformer - eliminating slope compensation and enabling stable operation at high frequencies. Its integrated ZVT driver (ZVTOUT) and gate driver (GTOUT) support resonant soft-switching of both boost diode and MOSFET, reducing EMI and improving efficiency.
It includes a precision analog multiplier with line-voltage feedforward (VRMS), voltage amplifier with soft-start, overvoltage protection (OVP) with 400mV hysteresis, and dual UVLO thresholds (10.5V turn-on / 9V turn-off). The device uses a 20-pin SOIC-DW package with GND-referenced analog inputs and rail-to-rail output swing capability on CAO and VAO.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 160–240 kHz typical; enables stable fixed-frequency PFC operation without external frequency trimming. |
| Current Amplifier GBW | 2.5–5 MHz; supports fast transient response and accurate current loop control up to 500kHz switching. |
| Reference Voltage | 7.5 V ±1% at 25°C; provides stable, low-drift bias for voltage and current loops in universal-input designs. |
| ZVT Drive Peak Current | ±0.75 A peak; sufficient to drive small auxiliary MOSFETs for zero-voltage turn-on in resonant snubbers. |
| Operating Temperature | −40°C to +85°C; qualified for industrial-grade AC-DC power supplies with extended thermal margins. |
| Startup Supply Current | 150 µA typical; minimizes pre-regulator loss during cold start and improves system efficiency at light load. |
| UVLO Turn-On Threshold | 10.5 V (typical); ensures reliable startup after bulk capacitor charging while avoiding brown-out oscillation. |
Pinout & Package
UC2855BDWTR is housed in a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NIPDAU lead finish, MSL Level-2-260°C-1 year.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CA | Inverting input of current amplifier | Accepts compensated feedback from CS; common-mode range −0.3 V to 5 V supports wide-swing error sensing. |
| CAO | Current amplifier output | Drives PWM comparator; rail-to-rail swing (0.1–7.5 V) enables full duty-cycle control range. |
| CI | Current synthesizer capacitor node | Integrates reconstructed inductor current waveform; requires external capacitor for time-constant tuning. |
| CS | Level-shifted current synthesizer output | Feeds current amplifier and peak-limit comparator; 1.5 V threshold disables GTOUT on overcurrent. |
| CT | Oscillator timing capacitor | Defines switching frequency via f ≈ 1/(11200·CT); minimum 200 pF recommended for layout immunity. |
| GTOUT | Main gate driver output | 1.5 A peak totem-pole output; requires ≥10 Ω series resistor and Schottky clamp to GND for robust MOSFET drive. |
| ZVTOUT | ZVT auxiliary gate driver | 750 mA peak output; synchronizes resonant snubber timing with main switch; supports high-current sync use. |
| VSENSE | Voltage amplifier inverting input | Feedback node for boost output regulation; nominal 3 V input enables standard resistive divider design. |
| VAO | Voltage amplifier output | Generates multiplier programming signal; swing limited to 0.1–6 V; <1.5 V inhibits multiplier output. |
| IAC | Multiplier line-current input | Accepts rectified AC line current proportional signal; 650 mV nominal offset eliminates zero-crossing compensation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated ZVT driver | Reduces MOSFET turn-on loss and diode reverse recovery stress, enabling 500 kHz operation with lower EMI and higher efficiency. |
| Inductor current synthesizer | Reconstructs continuous inductor current from one current sense transformer, eliminating need for shunt resistor and associated losses. |
| Line-voltage feedforward (VRMS) | Compensates for input RMS variation in real time, maintaining constant power delivery and enabling universal input (85–265 VAC) operation. |
| High-bandwidth current amplifier | 5 MHz gain-bandwidth product ensures fast current-loop response and stability under dynamic load and line transients. |
| Dual-threshold UVLO | 10.5 V turn-on / 9 V turn-off hysteresis prevents oscillatory startup during marginal input conditions. |
Applications
| Industrial AC-DC Power Supplies | Server & Telecom Rectifiers |
|---|---|
|
Use Scenario: 1–3 kW front-end rectifier in 19-inch rack-mounted telecom power systems with universal input and strict EN 61000-3-2 Class A compliance. IC Role / Device Role / Timing Role: Primary PFC controller managing boost stage current shaping and output voltage regulation via average current mode with ZVT-assisted soft switching. Use Value: Enables >98% efficiency at 50% load and <5% THD across full input range by eliminating slope compensation and minimizing switching loss. |
Use Scenario: High-density 80 PLUS Titanium-certified server PSU where thermal headroom and EMI filtering size are constrained. IC Role / Device Role / Timing Role: Fixed-frequency PFC controller coordinating GTOUT and ZVTOUT to achieve zero-voltage turn-on of main and auxiliary switches. Use Value: Reduces EMI filter volume by 30% and lowers heatsink requirements through 500 kHz operation and active snubbing. |
| Medical Grade AC-DC Modules | Industrial Motor Drives |
|
Use Scenario: IEC 60601-1 compliant medical power supply requiring low leakage, high reliability, and no audible noise from magnetics. IC Role / Device Role / Timing Role: Core PFC regulator enforcing near-unity power factor and low harmonic distortion while supporting soft-start and OVP lockout. Use Value: Achieves <3% THD at full load and meets IEC 61000-3-12 limits without additional harmonic filters. |
Use Scenario: Variable-frequency drive front-end with regenerative braking, requiring stable DC bus under bidirectional power flow. IC Role / Device Role / Timing Role: Boost PFC controller maintaining regulated 750 VDC bus despite large line and load transients. Use Value: Sustains regulation during 20 ms line sags via fast voltage loop (5 MHz CA) and programmable OVP hysteresis. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PFC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3855BDW | Same pinout and architecture but rated for 0°C to +70°C; lower temperature grade and NRND status. | Suitable only for commercial-temperature environments; not qualified for industrial ambient extremes. | Select UC2855BDWTR when operating beyond 70°C ambient or requiring long-term industrial availability. |
| L6562ADTR | Fixed-frequency average current-mode PFC controller with integrated 650 V startup circuit; no ZVT driver; 650 kHz max frequency. | Lacks resonant snubber support; requires external HV startup network; simpler layout but higher EMI at same frequency. | Choose L6562ADTR for cost-sensitive, lower-power (<500 W) designs where ZVT complexity is unnecessary. |
Compared with UC3855BDW and L6562ADTR, UC2855BDWTR uniquely combines industrial temperature rating, integrated ZVT drive, and current synthesizer functionality-enabling compact, high-efficiency PFC stages above 1 kW without compromising thermal or EMI performance.
Availability
UC2855BDWTR is available at Aetrix Electronics and suitable for industrial AC-DC power supplies, telecom rectifiers, medical-grade PSUs, and motor drive front-ends requiring stable component supply and long-lifecycle support.
Supply support for UC2855BDWTR 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 and embedded processing technologies, with decades of expertise in power management ICs and industrial-grade controllers.
The UC2855B belongs to TI's legacy high-performance PFC controller family, engineered specifically for high-efficiency, high-frequency boost preregulators in industrial and telecom power systems.
FAQ
What is the operating temperature range of the UC2855BDWTR?
The UC2855BDWTR is specified for −40°C to +85°C junction temperature operation. This industrial-grade rating ensures reliable performance in demanding environments such as enclosed power cabinets, outdoor telecom enclosures, and factory-floor motor drives where ambient temperatures exceed commercial limits. The UC2855BDWTR maintains full parameter compliance across this range per its Electrical Characteristics table.
Does UC2855BDWTR support ZVT (Zero Voltage Transition) operation out of the box?
Yes, UC2855BDWTR integrates a dedicated ZVT driver (ZVTOUT) with ±0.75 A peak current capability and programmable pulse width. When used with an auxiliary MOSFET, diode, and small inductor, it enables resonant soft-switching of the main boost switch - reducing turn-on loss, diode recovery stress, and EMI. No external logic or timing circuitry is required to activate ZVT functionality in the UC2855BDWTR.
How does UC2855BDWTR implement average current mode control without slope compensation?
The UC2855BDWTR uses an internal current synthesizer that reconstructs the continuous inductor current waveform from a single current sense transformer. By buffering the current during switch-on and discharging CI proportionally to dI/dt during switch-off, it generates a stable, noise-immune current representation - eliminating subharmonic oscillation and removing the need for external slope compensation networks in the UC2855BDWTR design.
What is the purpose of the VRMS pin on UC2855BDWTR?
The VRMS pin on UC2855BDWTR accepts a voltage proportional to the AC input RMS value and feeds it into the internal analog multiplier. This enables real-time feedforward compensation: the multiplier output scales inversely with VRMS², maintaining constant power delivery across universal input ranges (85–265 VAC) and improving transient response to line fluctuations - a core function of the UC2855BDWTR's power factor correction architecture.
Can UC2855BDWTR replace UC3855BDW in an existing design?
UC2855BDWTR is pin-compatible and functionally identical to UC3855BDW but rated for −40°C to +85°C versus 0°C to +70°C. Electrical parameters including UVLO thresholds, oscillator accuracy, and driver strengths match exactly. However, UC3855BDW is NRND and lacks industrial temperature qualification - so UC2855BDWTR serves as a direct drop-in replacement where extended temperature operation or long-term supply assurance is required.
UC2855BDWTR 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:
- 10.5V ~ 20V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
UC2855BDWTR FAQ
1.How can I place an order for UC2855BDWTR through Aetrix?
Please submit a Request for Quotation (RFQ) for UC2855BDWTR 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 UC2855BDWTR reliable?
The price and inventory of UC2855BDWTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC2855BDWTR is usually 5 days.
3.What payment methods are accepted for UC2855BDWTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC2855BDWTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC2855BDWTR?
UC2855BDWTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC2855BDWTR 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 UC2855BDWTR?
For technical support, including UC2855BDWTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC2855BDWTR requirements.
6.How does Aetrix verify that UC2855BDWTR is sourced from the original manufacturer or authorized distributors?
All UC2855BDWTR 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 UC2855BDWTR meets industry standards.
7.What is the process for return or replacement of UC2855BDWTR?
All UC2855BDWTR units undergo pre-shipment inspection (PSI). If there is an issue with UC2855BDWTR, 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 UC2855BDWTR part is unused and in its original packaging.
Return procedure for UC2855BDWTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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