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Texas Instruments UCC28502DWTR
- Part No.:
- UCC28502DWTR
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
UCC28502DWTR.pdf
- Description:
- IC PFC CTR AVERAGE 100KHZ 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,608
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Product details
Overview
UCC28502DWTR from Texas Instruments is a dual-stage power factor correction (PFC) and DC-DC controller IC integrating average-current-mode PFC control with peak-current-mode downstream PWM control. It delivers near-unity power factor, programmable 80–120 kHz oscillator frequency, 16.5 V/10 V UVLO threshold with 6.3 V hysteresis, and synchronized leading-edge (PFC) / trailing-edge (PWM) modulation for reduced bulk-capacitor ripple. It targets universal-input AC-DC front-end designs in industrial and telecom power supplies.
For engineers reviewing the UCC28502DWTR datasheet, UCC28502DWTR pinout, UCC28502DWTR application, or UCC28502DWTR equivalent, key selection criteria include its dual-stage control architecture, wide-input-voltage feedforward (VFF) implementation, 50% max duty cycle clamp on GT2, zero-power detection at 0.33 V VAOUT, and compatibility with boost PFC + forward/flyback secondary stages requiring optocoupled error feedback via VERR.
Technical Context
The UCC28502DWTR implements a two-loop control system: the PFC stage uses average current-mode control with a high-linearity analog multiplier (IAC input, MOUT output), voltage amplifier (VAOUT), and CAOUT current-sense amplifier to shape line current; the second stage employs peak-current-mode control with external error signal injection at VERR and internal slope compensation via ISENSE2. Its VFF generation mirrors IAC through a single-pole RC filter to enable constant input power across 85–265 VRMS inputs.
UVLO2 thresholds are configured for wide-range operation (6.75 V turn-on, 3.0 V hysteresis), enabling second-stage start-up only after PFC output reaches ≥50% of nominal bulk voltage-preventing overstress during brownout. The device integrates dual gate drivers (GT1 for PFC, GT2 for PWM), programmable soft-start (SS2), and overvoltage/enable logic (OVP/ENBL) that disables both stages below 1.9 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 80–120 kHz; set by RT/CT network; enables EMI optimization and transformer size reduction. |
| VCC UVLO Threshold | 16.5 V turn-on / 10 V turn-off; supports bootstrap bias supply operation without auxiliary winding. |
| PWM UVLO2 Hysteresis | 3.0 V; ensures robust second-stage shutdown during bulk voltage sag to 50% nominal. |
| Reference Voltage | 7.5 V ±15 mV; stable internal reference for PKLMT, OVP, and biasing; delivers 10 mA sink/source. |
| Gate Drive Capability | GT1/GT2: 1.2 A pulsed, 200 mA continuous; drives MOSFET gates directly with <50 ns rise/fall times. |
| Zero-Power Detection | 0.175–0.500 V VAOUT threshold; shuts down PFC output when boost voltage collapses, saving standby power. |
| Current Sense Threshold | ISENSE2 comparator: 0.94–1.15 V; sets peak current limit for second-stage FETs with slope compensation support. |
Pinout & Package
UCC28502DWTR is housed in a 20-pin SOIC (DW) package with exposed thermal pad, rated for –40°C to +85°C operating temperature. Pin assignments follow TI's standard DW top-view layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GT1 | PFC gate driver output | Drives boost switch MOSFET; supports >95% duty cycle; requires ≥10.5 Ω series gate resistor. |
| GT2 | DC-DC gate driver output | Drives forward/flyback primary switch; internally clamped to ≤50% duty cycle for safe transformer reset. |
| IAC | AC line current sensing input | Current-mode input to analog multiplier; max 500 µA; enables RMS feedforward via VFF mirroring. |
| VFF | RMS feedforward voltage node | Generated by IAC mirroring + RC filter; scales with VLINE2 to maintain constant input power across 3:1 input range. |
| VERR | Second-stage error amplifier input | Accepts optocoupler-derived error signal; 4.5 V internal clamp prevents >50% duty cycle under fault conditions. |
| SS2 | PWM soft-start capacitor terminal | Charges with –10 µA current source; controls ramped PWM enable; discharges rapidly on disable or UVLO2 dropout. |
| OVP/ENBL | Window comparator input | Disables PFC if VAOUT > 6.67% above nominal; disables both stages if pulled <1.9 V; defines active PWM range. |
| PKLMT | PFC peak current limit threshold | 0 V reference; level-shifted current sense signal applied here sets instantaneous overcurrent trip point. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated dual-stage control | Single-chip solution eliminates separate PFC and PWM controllers, reducing BOM count and PCB area. |
| Synchronized modulation scheme | Leading-edge PFC + trailing-edge PWM minimizes overlap conduction, cutting bulk-capacitor ripple current by up to 40% vs unsynchronized designs. |
| Programmable soft-start (SS2) | Controlled ramp-up of second-stage duty cycle prevents inrush stress on transformer and output rectifiers during cold start. |
| VFF-based line feedforward | Eliminates high-voltage resistive divider networks; reduces component count and improves accuracy of input power regulation. |
| Wide UVLO2 hysteresis (3.0 V) | Enables reliable second-stage operation down to 50% of nominal bulk voltage-critical for brownout resilience in telecom systems. |
Applications
| Industrial AC-DC Power Supplies | Telecom Rectifier Modules |
|---|---|
Use Scenario: 85–265 VRMS input, 12 V/10 A output power supply for PLC controllers and motor drives. IC Role / Device Role / Timing Role: UCC28502DWTR manages boost PFC pre-regulation and isolated forward converter secondary control via optocoupler feedback. Use Value: Achieves >0.99 power factor and meets EN61000-3-2 Class A harmonic limits while supporting hold-up time >16 ms. | Use Scenario: -48 V telecom rectifier with universal AC front-end and hot-swap capability. IC Role / Device Role / Timing Role: UCC28502DWTR coordinates staged start-up: PFC stabilizes first, then second stage ramps via SS2 only after bulk voltage exceeds 50% nominal. Use Value: Prevents second-stage overload during low-line brownout, extending system uptime and protecting downstream DC-DC converters. |
| Medical Equipment Power Front-Ends | Server PSU Auxiliary Rails |
Use Scenario: IEC 60601-compliant 24 V/5 A auxiliary supply for imaging equipment with strict leakage and EMI requirements. IC Role / Device Role / Timing Role: UCC28502DWTR implements average-current-mode PFC with low-distortion IAC sensing and VFF feedforward to minimize THD. Use Value: Reduces input current harmonics to <5% THD at full load, easing compliance with medical EMC standards. | Use Scenario: 5 V/3 A standby rail in modular server PSUs requiring high efficiency at light loads. IC Role / Device Role / Timing Role: UCC28502DWTR enables zero-power detection (0.33 V VAOUT threshold) to disable PFC when main outputs are unpowered. Use Value: Cuts no-load input power to <300 µA, meeting ENERGY STAR® v8.0 Level VI standby loss requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-stage PFC+PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28502N | Same functional spec, but in 20-pin PDIP (N) package; higher thermal resistance; no exposed pad. | Preferred for prototyping or low-volume through-hole assembly; not suitable for high-power density or convection-limited environments. | Select UCC28502N only when manual soldering or socket-based validation is required; UCC28502DWTR is optimal for production SMT layouts. |
| UCC38502DWTR | Identical pinout and functionality, but rated for 0°C to 70°C ambient; lower cost; same DWTR tape-and-reel packaging. | Targeted at commercial-grade applications where extended temperature range is unnecessary. | Choose UCC38502DWTR for cost-sensitive consumer or networking gear; UCC28502DWTR remains preferred for industrial/telecom deployments requiring –40°C startup. |
Compared with UCC28502N and UCC38502DWTR, the UCC28502DWTR uniquely combines industrial temperature rating (–40°C to +85°C), thermally enhanced SOIC-DW package, and tape-and-reel delivery-making it the default choice for volume production of ruggedized AC-DC power supplies.
Availability
UCC28502DWTR is available at Aetrix Electronics and suitable for industrial AC-DC power supplies, telecom rectifier modules, and medical equipment front-ends requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for UCC28502DWTR 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 power conversion innovation.
The UCC2850x product line was designed specifically for cost-effective, high-efficiency active PFC + isolated DC-DC power supplies targeting industrial, telecom, and medical equipment requiring universal AC input and stringent harmonic compliance.
FAQ
What is the purpose of the VFF pin on the UCC28502DWTR?
The VFF pin on the UCC28502DWTR generates a feedforward voltage proportional to the square of the AC input voltage, derived by mirroring the IAC current through an external RC filter. This enables the controller to maintain constant input power across a 3:1 input voltage range (85–265 VRMS) without high-voltage resistive dividers. In the UCC28502DWTR, VFF directly scales the multiplier gain to stabilize PFC stage power delivery, improving line regulation and reducing component count in the front-end design.
How does the UCC28502DWTR handle start-up sequencing between the PFC and DC-DC stages?
The UCC28502DWTR implements internal start-up sequencing by monitoring the VAOUT voltage: the second-stage PWM remains disabled until the PFC output reaches ≥50% of nominal bulk voltage, preventing excessive inrush into the downstream converter. Once triggered, SS2 initiates a controlled soft-start ramp. This behavior is fixed in the UCC28502DWTR due to its 3.0 V UVLO2 hysteresis-distinct from UCC28500/501 variants with narrower hysteresis-and ensures robust operation during brownout conditions.
Can the UCC28502DWTR be used with a flyback topology for the second stage?
Yes, the UCC28502DWTR supports flyback topologies for the second stage via its VERR input and peak-current-mode control architecture. An optocoupler delivers the secondary-side error signal to VERR, while ISENSE2 accepts the primary-side current sense signal-optionally summed with the CT ramp for slope compensation. The UCC28502DWTR's 50% maximum duty cycle clamp on GT2 is compatible with flyback operation, and its zero-power detection (0.33 V VAOUT threshold) enables automatic shutdown when output loads are removed.
What is the function of the PKLMT pin on the UCC28502DWTR?
The PKLMT pin on the UCC28502DWTR serves as the PFC stage peak current limit threshold input, referenced to 0 V. A resistor divider from the negative side of the PFC current-sense resistor to VREF level-shifts the sensed voltage to match the 0 V threshold, setting the instantaneous overcurrent trip point. This protects the boost switch against short-circuit or overload events. In the UCC28502DWTR, PKLMT operates independently of the second-stage current limit and features 150–500 ns propagation delay for fast fault response.
Does the UCC28502DWTR support both voltage-mode and current-mode control for the second stage?
Yes, the UCC28502DWTR supports both control modes for the second stage. Current-mode control is implemented by feeding the sensed primary current into ISENSE2, optionally combined with the CT oscillator ramp for slope compensation. Voltage-mode control is enabled by routing the CT ramp signal-via a voltage divider-into ISENSE2 instead of the current sense signal. This flexibility allows designers to optimize stability and transient response based on transformer design and load characteristics in the final UCC28502DWTR application.
UCC28502DWTR 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:
- 100kHz
- Current - Startup:
- 150 µA
- Voltage - Supply:
- 9.7V ~ 18V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
UCC28502DWTR FAQ
1.How can I place an order for UCC28502DWTR through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC28502DWTR 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 UCC28502DWTR reliable?
The price and inventory of UCC28502DWTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC28502DWTR is usually 5 days.
3.What payment methods are accepted for UCC28502DWTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC28502DWTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC28502DWTR?
UCC28502DWTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC28502DWTR 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 UCC28502DWTR?
For technical support, including UCC28502DWTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC28502DWTR requirements.
6.How does Aetrix verify that UCC28502DWTR is sourced from the original manufacturer or authorized distributors?
All UCC28502DWTR 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 UCC28502DWTR meets industry standards.
7.What is the process for return or replacement of UCC28502DWTR?
All UCC28502DWTR units undergo pre-shipment inspection (PSI). If there is an issue with UCC28502DWTR, 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 UCC28502DWTR part is unused and in its original packaging.
Return procedure for UCC28502DWTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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