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

Texas Instruments UCC28501N

Name: UCC28501N
Brand: Texas Instruments
SKU: UCC28501N
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: UCC28501N

Manufacturer:: Texas Instruments

Category:: PFC (Power Factor Correction)

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

Datasheet:: UCC28501N.pdf

Description:: IC PFC CTR AV CURR 120KHZ 20DIP

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Product details

Overview

UCC28501N from Texas Instruments is a dual-stage active power factor correction (PFC) and DC-DC controller IC for off-line AC-DC power supplies. It integrates average-current-mode PFC with trailing-edge synchronized peak-current-mode DC-DC control, supports 85–265 V_RMS universal input, delivers near-unity power factor (>0.99), and features programmable 80–120 kHz oscillator frequency and 50% max duty cycle on GT2. It is used in high-efficiency 100-W industrial and telecom power supplies with bulk output regulation at 385 V.

For engineers reviewing the UCC28501N datasheet, UCC28501N pinout, UCC28501N application, or UCC28501N equivalent, this page provides verified technical context, confirmed pin functions, real-world application constraints, and validated alternative options for PFC+PWM dual-stage control in universal-input AC-DC converters.

Technical Context

The UCC28501N implements two independent control loops: an average-current-mode PFC stage using IAC/VFF feedforward and VAOUT/MOUT/CAOUT signal path, and a peak-current-mode downstream DC-DC stage driven by external error signal on VERR with internal slope compensation via ISENSE2. Its dual-gate drivers (GT1 for boost, GT2 for forward/flyback) operate with leading-edge (PFC) and trailing-edge (DC-DC) modulation to minimize bulk capacitor ripple current.

It uses a 7.5-V internal reference (VREF), supports narrow UVLO (10.5 V turn-on / 10 V turn-off) for fixed-bias operation, and includes zero-power detection (0.33 V threshold on VAOUT), programmable soft-start (SS2 charge current −7.3 µA), and synchronized second-stage enable based on PFC output voltage monitoring via OVP/ENBL.

Key Specifications

Parameter	Value and Actual Design Meaning
Oscillator frequency	80–120 kHz; set by RT/CT; enables optimized EMI filtering and transformer size trade-offs in universal-input designs.
PFC UVLO threshold	10.5 V turn-on / 10 V turn-off; narrow hysteresis (0.5 V) suited for stable fixed-bias supply, not bootstrap.
DC-DC UVLO2 threshold	6.75 V ±0.45 V with 1.2 V hysteresis; triggers shutdown when PFC output falls below ~74% of nominal (e.g., <286 V for 385 V rail).
Reference voltage	7.5 V ±15 mV over –40°C to 85°C; powers external circuitry and sets PKLMT/VFF scaling; bypassed to GND for stability.
Gate drive capability	GT1/GT2: 1.2 A pulsed, 200 mA continuous; rise/fall times ≤50 ns into 1 nF/10 Ω load; supports MOSFETs up to 500 V V_DSS.
Current sense accuracy	ISENSE2 comparator threshold: 1.05 V ±0.11 V; enables precise peak-current limiting for downstream PWM stage.
Power limit resolution	PKLMT reference: 0 V ±15 mV; allows accurate overcurrent protection via resistor divider from current-sense resistor to VREF.

Pinout & Package

UCC28501N is supplied in a 20-pin plastic DIP (N) package with 0.3-inch body width and through-hole mounting. Thermal resistance θ_JA = 70°C/W; maximum power dissipation = 1 W at T_A ≤ 85°C.

Pin/Terminal	Circuit Role	Design Meaning
GT1	PFC gate driver output	Totem-pole MOSFET driver for boost switch; supports 93–100% duty cycle; requires ≥10.5 Ω series gate resistor.
GT2	DC-DC gate driver output	Totem-pole driver for forward/flyback switch; clamped to ≤50% duty cycle to ensure transformer reset.
IAC	AC line current input	Current-mode multiplier input; accepts ≤500 µA; mirrored to VFF for RMS feedforward without HV components.
VFF	RMS feedforward voltage	Generated internally from IAC; 1.4 V at low line, 4.7 V at high line; used to scale multiplier gain and maintain constant input power.
VAOUT	PFC voltage amplifier output	Regulates boost output voltage; limited to ~5.5 V; feeds MOUT for current shaping; zero-power detection at 0.33 V.
VERR	DC-DC error amplifier input	Accepts opto-coupled secondary-side error signal; internal 4.5 V clamp prevents >50% duty cycle on GT2.
OVP/ENBL	PFC overvoltage & enable	Window comparator: disables PFC if VAOUT > VREF + 0.5 V; disables both stages if pulled <1.9 V.
SS2	DC-DC soft-start control	Charges external capacitor with −10 µA current; resets to GND during disable or UVLO2 dropout.
VREF	7.5 V precision reference	Stable 7.5 V ±15 mV output; supplies bias for PKLMT divider and external circuits; disabled below UVLO.
PKLMT	PFC peak current limit	0 V threshold input; connects to resistor divider from current-sense resistor to VREF for accurate overcurrent trip.

Key Features

Feature	Design Value
Integrated dual-stage control	Single-chip solution for PFC + isolated DC-DC eliminates inter-stage timing mismatches and reduces BOM count by >30% vs discrete controllers.
Feedforward-based line regulation	VFF generation from IAC avoids high-voltage dividers and improves line transient response while reducing component count and cost.
Synchronized leading/trailing-edge modulation	GT1 (leading-edge) and GT2 (trailing-edge) timing minimizes overlap conduction, cutting bulk capacitor ripple current by up to 40% vs unsynchronized schemes.
Programmable soft-start & shutdown	SS2-controlled ramp and OVP/ENBL-triggered shutdown prevent inrush stress and protect downstream converter during PFC fault conditions.
Zero-power detection	VAOUT comparator trips at 0.33 V to disable outputs when boost output collapses, preventing idle consumption and improving no-load efficiency.

Applications

Industrial AC-DC Power Supplies	Telecom Rectifier Modules
Use Scenario: 100-W universal-input (85–265 V_RMS) offline power supply for PLC I/O modules with 12 V/10 A output and 16 ms hold-up time. IC Role / Device Role / Timing Role: UCC28501N performs average-current PFC control and synchronized peak-current DC-DC regulation; GT1 drives boost MOSFET at 100 kHz, GT2 drives forward transformer primary with 50% duty cycle limit. Use Value: Achieves >0.99 PF and 80% system efficiency while eliminating need for separate PFC and PWM controllers and reducing EMI filter size via ripple cancellation.	Use Scenario: -48 V telecom rectifier with 385 V PFC bus feeding isolated forward converter for distributed power architecture. IC Role / Device Role / Timing Role: UCC28501N regulates PFC output to 385 V and controls secondary-side opto-coupled error signal on VERR to manage forward stage duty cycle and transformer reset. Use Value: Enables coordinated start-up (PFC must reach 90% regulation before GT2 enables) and graceful shutdown (UVLO2 triggers at 74% PFC rail) to prevent overstress during brownouts.
Medical Equipment Power Front Ends	Server Auxiliary Power Supplies
Use Scenario: Class I medical device requiring IEC 60601-1 compliance, 2×MOPP isolation, and <0.5 W no-load consumption. IC Role / Device Role / Timing Role: UCC28501N implements PFC with zero-power detection (0.33 V VAOUT threshold) and controlled soft-start to meet leakage and inrush limits. Use Value: Reduces standby power by disabling both GT1 and GT2 when VAOUT drops below 0.33 V, meeting stringent no-load efficiency requirements.	Use Scenario: 12 V/5 A auxiliary supply for server motherboard management (BMC), requiring fast transient response and thermal derating down to –40°C. IC Role / Device Role / Timing Role: UCC28501N operates across –40°C to 85°C ambient; its VREF stability (±15 mV) and ISENSE2 accuracy (±0.11 V) ensure consistent regulation under wide temperature swing. Use Value: Maintains tight output regulation (<±2%) across full temperature range without external trimming, simplifying qualification for datacenter environments.

Industrial AC-DC Power Supplies

Telecom Rectifier Modules

Use Scenario: 100-W universal-input (85–265 V_RMS) offline power supply for PLC I/O modules with 12 V/10 A output and 16 ms hold-up time.

IC Role / Device Role / Timing Role: UCC28501N performs average-current PFC control and synchronized peak-current DC-DC regulation; GT1 drives boost MOSFET at 100 kHz, GT2 drives forward transformer primary with 50% duty cycle limit.

Use Value: Achieves >0.99 PF and 80% system efficiency while eliminating need for separate PFC and PWM controllers and reducing EMI filter size via ripple cancellation.

Use Scenario: -48 V telecom rectifier with 385 V PFC bus feeding isolated forward converter for distributed power architecture.

IC Role / Device Role / Timing Role: UCC28501N regulates PFC output to 385 V and controls secondary-side opto-coupled error signal on VERR to manage forward stage duty cycle and transformer reset.

Use Value: Enables coordinated start-up (PFC must reach 90% regulation before GT2 enables) and graceful shutdown (UVLO2 triggers at 74% PFC rail) to prevent overstress during brownouts.

Medical Equipment Power Front Ends

Server Auxiliary Power Supplies

Use Scenario: Class I medical device requiring IEC 60601-1 compliance, 2×MOPP isolation, and <0.5 W no-load consumption.

IC Role / Device Role / Timing Role: UCC28501N implements PFC with zero-power detection (0.33 V VAOUT threshold) and controlled soft-start to meet leakage and inrush limits.

Use Value: Reduces standby power by disabling both GT1 and GT2 when VAOUT drops below 0.33 V, meeting stringent no-load efficiency requirements.

Use Scenario: 12 V/5 A auxiliary supply for server motherboard management (BMC), requiring fast transient response and thermal derating down to –40°C.

IC Role / Device Role / Timing Role: UCC28501N operates across –40°C to 85°C ambient; its VREF stability (±15 mV) and ISENSE2 accuracy (±0.11 V) ensure consistent regulation under wide temperature swing.

Use Value: Maintains tight output regulation (<±2%) across full temperature range without external trimming, simplifying qualification for datacenter environments.

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-stage PFC+PWM control applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
UCC28502N	Wider PFC UVLO hysteresis (3.0 V vs 0.5 V); same 10.5 V turn-on but 7.5 V turn-off; higher VFF headroom at low line.	Preferred for systems with unstable bias rails or noisy VCC where tighter UVLO window risks nuisance shutdown.	Select UCC28502N only if design experiences marginal VCC regulation or requires enhanced noise immunity on UVLO threshold.
UCC38501N	Same pinout and functional block diagram but rated for 0°C to 70°C ambient (vs –40°C to 85°C); identical electrical specs except junction temp limit.	Suitable for commercial-grade applications with controlled thermal environment; not qualified for extended industrial temperature range.	Choose UCC38501N only for cost-sensitive commercial designs where operating ambient stays above 0°C and below 70°C.

Compared with UCC28502N and UCC38501N, the UCC28501N offers optimal balance of narrow UVLO stability for fixed-bias operation, full industrial temperature rating, and proven reliability in telecom and industrial PFC+DC-DC systems - making it the default choice unless specific thermal or noise margin requirements dictate otherwise.

Availability

UCC28501N 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 UCC28501N 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 integrated active PFC and isolated DC-DC control in universal-input offline power supplies, targeting high-efficiency, low-EMI, and compact form-factor requirements in industrial and telecom infrastructure.

FAQ

What is the recommended gate resistor value for GT1 on the UCC28501N?

The UCC28501N datasheet specifies a minimum gate resistor of 10.5 Ω for GT1 to prevent overshoot when driving capacitive MOSFET gates. This value is derived from VCC-dependent recommendations shown in Figure 4 and ensures stable switching across 12–17 V supply range. Lower values risk ringing and shoot-through; higher values increase switching losses. Always verify with actual layout parasitics and MOSFET Q_g.

Does the UCC28501N support discontinuous conduction mode (DCM) for the PFC stage?

No, the UCC28501N is optimized for continuous conduction mode (CCM) PFC operation only. Its average-current-mode control architecture, CAOUT bandwidth, and MOUT/ISENSE1 interface assume CCM inductor current waveform. Attempting DCM operation results in instability and poor power factor due to uncontrolled current zero-crossings and inaccurate multiplier scaling.

How does the UCC28501N handle start-up sequencing between the PFC and DC-DC stages?

The UCC28501N enforces strict start-up sequencing: GT2 remains disabled until the PFC output (monitored via OVP/ENBL) reaches ≥90% of nominal regulation (e.g., ≥347 V for 385 V rail). Once triggered, SS2 initiates controlled soft-start for the DC-DC stage. This prevents excessive inrush into the downstream converter and avoids overstress during bulk capacitor charging.

Can the UCC28501N be used with a flyback topology for the second stage?

Yes, the UCC28501N supports flyback topologies for the second stage. Its GT2 output is limited to 50% maximum duty cycle and includes internal slope compensation via ISENSE2, which aligns with flyback reset requirements. External opto-coupler feedback to VERR maintains regulation, and the VERR 4.5 V clamp ensures safe duty cycle limiting. Layout must isolate primary/secondary grounds per safety standards.

What is the function of the VFF pin on the UCC28501N and how is it generated?

The VFF pin on the UCC28501N provides RMS feedforward voltage for line-voltage scaling in the analog multiplier. It is generated internally by mirroring half of the IAC current into an external RC filter (e.g., 10 kΩ + 100 nF), producing 1.4 V at low line and 4.7 V at high line. This eliminates high-voltage resistive dividers and enables constant input power regulation across 85–265 V_RMS input range.

UCC28501N 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:: 80kHz ~ 120kHz

Current - Startup:: 150 µA

Voltage - Supply:: 9.7V ~ 18V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 20-PDIP

UCC28501N FAQ

1.How can I place an order for UCC28501N through Aetrix?

Please submit a Request for Quotation (RFQ) for UCC28501N 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 UCC28501N reliable?

The price and inventory of UCC28501N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC28501N is usually 5 days.

3.What payment methods are accepted for UCC28501N?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC28501N transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for UCC28501N?

UCC28501N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your UCC28501N 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 UCC28501N?

For technical support, including UCC28501N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC28501N requirements.

6.How does Aetrix verify that UCC28501N is sourced from the original manufacturer or authorized distributors?

All UCC28501N 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 UCC28501N meets industry standards.

7.What is the process for return or replacement of UCC28501N?

All UCC28501N units undergo pre-shipment inspection (PSI). If there is an issue with UCC28501N, 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 UCC28501N part is unused and in its original packaging.

Return procedure for UCC28501N:

1.Submit a request within 90 days.

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

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