My Inquiry
My Account
Texas Instruments UCC28502N
- Part No.:
- UCC28502N
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
UCC28502N.pdf
- Description:
- IC PFC CTR AV CURR 100KHZ 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,967
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
UCC28502N from Texas Instruments is a dual-stage power factor correction (PFC) and DC-DC controller IC for AC-DC power supplies. It integrates average-current-mode PFC with trailing-edge synchronized peak-current-mode second-stage control, supports 85–265 VRMS universal input, delivers near-unity power factor (>0.99), and features programmable 80–120 kHz oscillator frequency, 16.5 V/10 V wide UVLO threshold, and 50% max duty cycle clamp on GT2.
For engineers reviewing the UCC28502N datasheet, UCC28502N pinout, UCC28502N application, or UCC28502N equivalent, key selection criteria include its dual-stage synchronization capability, feedforward line regulation via VFF, zero-power detection at VAOUT < 0.33 V, and compatibility with boost PFC + forward/flyback secondary-stage topologies requiring isolated error feedback.
Technical Context
The UCC28502N implements two independent control loops: an average-current-mode PFC stage using IAC current sensing and VFF-based RMS feedforward to maintain constant input power across 3:1 input voltage range, and a peak-current-mode DC-DC stage accepting external error signal via VERR with internal soft-start (SS2) and UVLO2 shutdown at 50% of nominal bulk voltage. Its multiplier architecture divides line current by VFF² to achieve accurate power limiting.
Leading-edge modulation on GT1 (PFC) and trailing-edge modulation on GT2 (DC-DC) minimize switch overlap, reducing bulk capacitor ripple current. The CAOUT/MOUT differential sensing path provides high noise immunity, while PKLMT enables precise PFC overcurrent protection via resistor-divider level-shifting referenced to VREF (7.5 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 80–120 kHz; set by RT/CT network, enables optimized EMI and efficiency trade-off in 100-W universal-input designs. |
| VREF Output | 7.5 V ±15 mV; precision reference powering external bias networks and PKLMT level-shift dividers. |
| UVLO Thresholds | 16.5 V turn-on / 10 V turn-off; wide hysteresis (6.3 V) ensures stable bootstrap startup under varying bulk conditions. |
| PWM Stage UVLO2 | 6.75 V turn-on with 3.0 V hysteresis; triggers shutdown when PFC output drops to 50% of nominal, protecting downstream converter. |
| Gate Drive Capability | GT1/GT2 sink/source ≥100 mA; supports direct drive of MOSFET gates without external buffers in ≤100-W applications. |
| Zero-Power Detection | VAOUT comparator threshold 0.33 V ±0.155 V; disables outputs when PFC output collapses, preventing unregulated operation. |
| Current Sense Accuracy | ISENSE2 comparator threshold 1.05 V ±0.11 V; enables precise pulse-by-pulse current limiting in second-stage PWM. |
Pinout & Package
UCC28502N is supplied in a 20-pin plastic DIP (N) package with 0.3-inch body width and through-hole mounting. Thermal performance is rated for operation from –40°C to +85°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GT1 | PFC gate driver output | Totem-pole MOSFET driver with 5–12 Ω pull-up/pull-down resistance; requires ≥10.5 Ω series gate resistor to limit overshoot. |
| GT2 | DC-DC gate driver output | Trailing-edge modulated output clamped to ≤50% duty cycle; accepts isolated error feedback via VERR. |
| IAC | AC line current input | Current-mode input (≤500 µA) to analog multiplier; enables low-distortion RMS feedforward generation at VFF. |
| VFF | RMS feedforward voltage | Generated by mirroring IAC through external RC filter; scales with √(VAC²), enabling constant-power PFC across 85–265 VRMS. |
| PKLMT | PFC peak current limit threshold | 0 V reference; external resistor divider from current-sense resistor negative terminal to VREF sets overcurrent trip point. |
| SS2 | Second-stage soft-start control | Charges external capacitor with –10 µA current source; ramps VERR-equivalent voltage to limit inrush during DC-DC startup. |
| OVP/ENBL | PFC overvoltage & enable input | Window comparator: disables PFC if VAOUT > 6.67% above nominal; pulls low to disable both stages and reset SS2. |
| VAOUT | Voltage amplifier output | Regulates PFC output voltage; internally clamped to ~5.5 V to prevent overshoot during transient recovery. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated dual-stage control | Eliminates need for separate PFC and PWM controllers, reducing BOM count and PCB area in 85–265 VRMS offline supplies. |
| VFF-based feedforward | Uses single-pole RC filter on VFF to derive RMS line voltage-no high-voltage resistors or complex scaling required. |
| Synchronized leading/trailing edge modulation | Reduces overlap between PFC and DC-DC switch conduction, cutting bulk capacitor ripple current by up to 40% vs unsynchronized designs. |
| Programmable soft-start | SS2 pin allows external capacitor selection to tailor DC-DC ramp time, preventing transformer saturation and inrush stress. |
| Wide UVLO hysteresis | 6.3 V hysteresis prevents oscillatory startup during brownout conditions common in universal-input applications. |
Applications
| Server Power Supply | Industrial Motor Drive PSU |
|---|---|
Use Scenario: 100-W universal-input AC-DC front-end for 12-V server board with hold-up time requirement. IC Role / Device Role / Timing Role: UCC28502N performs PFC regulation and isolated forward-converter control with synchronized timing to minimize output capacitor stress. Use Value: Achieves >0.99 PF and 80% system efficiency while meeting EN61000-3-2 Class A harmonic limits without additional filtering. | Use Scenario: Compact, ruggedized power supply for PLC I/O modules operating from 85–265 VRMS mains with variable load profiles. IC Role / Device Role / Timing Role: UCC28502N manages boost PFC and flyback-derived auxiliary rails, using zero-power detection to disable outputs during undervoltage faults. Use Value: Enables automatic restart after brownout recovery and eliminates need for external supervisor ICs due to integrated UVLO2 and OVP/ENBL logic. |
| Medical Diagnostic Equipment PSU | LED Driver Front-End |
Use Scenario: Low-noise, high-reliability power supply for ultrasound imaging systems requiring strict EMI compliance and thermal stability. IC Role / Device Role / Timing Role: UCC28502N controls continuous-conduction-mode boost PFC and opto-coupled forward converter, leveraging CAOUT/MOUT differential sensing for noise immunity. Use Value: Reduces conducted EMI by 8 dBµV through synchronized switching and feedforward line regulation, easing CISPR 11 certification. | Use Scenario: High-efficiency, dimmable LED driver with active PFC for commercial lighting fixtures operating on global mains. IC Role / Device Role / Timing Role: UCC28502N regulates bulk DC bus and drives secondary-side buck-boost LED current controller via VERR feedback loop. Use Value: Maintains >0.95 PF across 10–100% load with <±2% output current regulation, supporting DALI and 0–10 V dimming interfaces. |
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 |
|---|---|---|---|
| UCC28502DW | Same electrical specs; SOIC-20 package with surface-mount footprint and lower thermal resistance (θJA = 70°C/W vs 90°C/W). | Preferred for automated assembly and space-constrained designs where thermal margin is critical. | Select UCC28502DW when PCB real estate or reflow process compatibility outweighs through-hole serviceability needs. |
| UCC38502N | Same pinout and function but rated for 0°C to 70°C ambient (vs –40°C to 85°C); identical UVLO2 hysteresis and oscillator accuracy. | Suitable for cost-sensitive consumer applications without extended temperature requirements. | Choose UCC38502N only if industrial temperature grade is not required and BOM cost reduction is prioritized. |
Compared with UCC28502DW and UCC38502N, the UCC28502N offers superior thermal robustness for convection-cooled industrial enclosures and maintains full functionality in legacy through-hole layouts without redesigning the PCB.
Availability
UCC28502N is available at Aetrix Electronics and suitable for server power supplies, industrial motor drive PSUs, medical diagnostic equipment power supplies, and LED driver front-ends requiring stable component supply and long-term manufacturability.
Supply support for UCC28502N 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 IC design and manufacturing.
The UCC2850x product line was developed specifically for cost-effective, high-efficiency two-stage AC-DC conversion in universal-input offline power supplies targeting industrial, medical, and computing applications.
FAQ
What is the primary function of the VFF pin on the UCC28502N?
The VFF pin on the UCC28502N generates a feedforward voltage proportional to the RMS value of the AC input line voltage. It is derived by mirroring the IAC current through an external RC filter, enabling the UCC28502N to maintain constant input power across 85–265 VRMS input ranges without high-voltage sensing components. This directly supports accurate power limiting and improved line regulation in the PFC stage.
How does the UCC28502N handle start-up sequencing between the PFC and DC-DC stages?
The UCC28502N internally coordinates start-up by monitoring the PFC output voltage via VAOUT. It holds the DC-DC stage disabled until VAOUT reaches within 10% of regulation, then initiates soft-start on SS2. If VAOUT drops below 50% of nominal during operation, the UCC28502N triggers UVLO2 to shut down GT2-preventing overstress of the downstream converter during brownout events.
Can the UCC28502N be used with a flyback topology for the second stage?
Yes, the UCC28502N supports flyback topologies for the second stage. Its VERR pin accepts externally generated error signals-typically delivered via optocoupler from the secondary side-and its peak-current-mode control with ISENSE2 sensing and 50% duty-cycle clamp is compatible with flyback transformer reset requirements. Designers must ensure proper slope compensation injection at ISENSE2 when implementing discontinuous conduction mode.
What is the purpose of the PKLMT pin on the UCC28502N?
The PKLMT pin on the UCC28502N serves as the PFC peak current limit threshold input. It operates at 0 V reference, so a resistor divider from the negative terminal of the PFC current-sense resistor to VREF (7.5 V) sets the overcurrent trip point. This enables precise, temperature-stable current limiting independent of sense-resistor tolerance, critical for reliable boost switch protection under line and load transients.
Does the UCC28502N require an external error amplifier for the second-stage DC-DC converter?
Yes, the UCC28502N does not include an internal error amplifier for the second stage. It relies on an external amplifier-typically located on the secondary side of an isolated topology-to generate the error signal fed into the VERR pin. This architecture supports optocoupler-based feedback and accommodates both voltage-mode and current-mode configurations depending on how the CT ramp is injected into ISENSE2.
UCC28502N 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:
- 100kHz
- 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
UCC28502N FAQ
1.How can I place an order for UCC28502N through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC28502N 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 UCC28502N reliable?
The price and inventory of UCC28502N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC28502N is usually 5 days.
3.What payment methods are accepted for UCC28502N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC28502N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC28502N?
UCC28502N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC28502N 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 UCC28502N?
For technical support, including UCC28502N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC28502N requirements.
6.How does Aetrix verify that UCC28502N is sourced from the original manufacturer or authorized distributors?
All UCC28502N 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 UCC28502N meets industry standards.
7.What is the process for return or replacement of UCC28502N?
All UCC28502N units undergo pre-shipment inspection (PSI). If there is an issue with UCC28502N, 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 UCC28502N part is unused and in its original packaging.
Return procedure for UCC28502N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
UCC28502N Tags
-
ICE2PCS01GXUMA1
Infineon Technologies
-
NCP1654BD133R2G
onsemi
-
MC33262DR2G
onsemi
-
ICE3PCS03GXUMA1
Infineon Technologies
-
NCP1631DR2G
onsemi
-
L4981BD013TR
STMicroelectronics
-
UCC28070DWR
Texas Instruments
-
UCC28070PWR
Texas Instruments
-
UC3854DWTR
Texas Instruments
-
L4981AD013TR
STMicroelectronics
-
UCC2817D
Texas Instruments
-
UC2854BDWTR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
