My Inquiry
My Account
Texas Instruments UCC38501DWTR
- Part No.:
- UCC38501DWTR
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
UCC38501DWTR.pdf
- Description:
- IC PFC CTR AVERAGE 100KHZ 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,358
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
UCC38501DWTR 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 control with peak-current-mode downstream PWM control, delivers 7.5-V reference accuracy ±12 mV over 0°C–70°C, supports 80–120 kHz programmable oscillator frequency, and features narrow UVLO (10.5 V turn-on / 9.7 V turn-off) optimized for fixed-bias operation in universal-input 85–265 VRMS systems.
For engineers reviewing the UCC38501DWTR datasheet, UCC38501DWTR pinout, UCC38501DWTR application, or UCC38501DWTR equivalent, this controller enables coordinated start-up sequencing, feedforward line regulation, leading-edge PFC + trailing-edge PWM modulation to minimize bulk-capacitor ripple, and synchronized soft-start for low-stress turn-on of both stages in high-efficiency 100-W+ PFC+forward converter designs.
Technical Context
The UCC38501DWTR implements a two-stage control architecture: its PFC section uses average current-mode control with analog multiplier-based IAC-to-MOUT signal path, RMS feedforward via VFF pin, and zero-power detection at VAOUT < 0.33 V; the second stage employs external error amplification (fed into VERR), peak-current sensing on ISENSE2, and 50% duty-cycle clamping with internal slope compensation support.
It features dual gate drivers (GT1 for boost, GT2 for downstream PWM), programmable oscillator (RT/CT), dedicated PFC overvoltage protection (OVP/ENBL), and independent UVLO thresholds-10.5 V/9.7 V for VCC and 6.75 V ±1.2 V for second-stage enable-with hysteresis tailored for stable operation across wide input voltage ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 80–120 kHz; set by RT resistor and CT capacitor; ensures stable switching across line and load variations. |
| Voltage Reference (VREF) | 7.5 V ±12 mV (0°C–70°C); powers external circuitry and serves as precision bias for PKLMT and OVP thresholds. |
| PFC UVLO Threshold | 10.5 V turn-on / 9.7 V turn-off; narrow hysteresis (0.3–0.5 V) supports fixed-bias supply operation without bootstrap winding. |
| Second-Stage UVLO (UVLO2) | 6.75 V ±1.2 V with 1.2 V hysteresis; disables PWM when PFC output drops below 74% nominal, preventing transformer saturation. |
| Gate Drive Capability | GT1/GT2: 1.2 A pulsed, 200 mA continuous; low RON (5–12 Ω pull-up, 2–10 Ω pull-down) enables direct MOSFET drive without external buffers. |
| Current Sense Accuracy | ISENSE2 threshold: 1.05 V ±0.11 V; supports precise peak-current limiting for forward converter primary-side control. |
| Power Limiting | PKLMT pin referenced to 0 V; accepts level-shifted current-sense signal for accurate PFC overcurrent protection. |
Pinout & Package
UCC38501DWTR is housed in a 20-pin SOIC (DW) package with exposed thermal pad, rated for 0°C to 70°C operating temperature. Pin assignments are fully defined in TI SLUS419C Rev. November 2001.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GT1 | PFC gate driver output | Drives boost switch MOSFET; supports up to 95% duty cycle; requires ≥10.5 Ω series gate resistor to suppress overshoot. |
| GT2 | Downstream PWM gate driver output | Drives forward converter primary switch; internally clamped to ≤50% duty cycle for safe transformer reset. |
| IAC | AC line current input | Current-mode input to analog multiplier; max 500 µA; enables low-distortion RMS feedforward generation at VFF pin. |
| VFF | RMS feedforward voltage node | Generated by mirroring IAC through external RC filter; scales with line voltage² to maintain constant input power. |
| VAOUT | PFC voltage amplifier output | Regulates boost output voltage; internally clamped to ~5.5 V; used for zero-power detection (<0.33 V disables outputs). |
| VERR | Second-stage error amplifier input | Accepts opto-coupled secondary-side error signal; internal 4.5-V clamp enforces ≤50% duty cycle for transformer reset. |
| OVP/ENBL | PFC overvoltage & second-stage enable | Window comparator: disables PFC above +6.67% boost OVP; pulls low to disable both stages and discharge SS2. |
| SS2 | Second-stage soft-start capacitor node | Charges externally with –10 µA current source; controls PWM ramp-up; rapidly discharges on fault or disable. |
| PKLMT | PFC peak current limit threshold | 0 V reference; use resistor divider from sense resistor negative terminal to VREF to set overcurrent trip point. |
| MOUT | Multiplier output / current amp inverting input | High-impedance node connecting multiplier and current amplifier; used for loop compensation between MOUT and CAOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated dual-stage control | Single-chip solution eliminates need for separate PFC and PWM controllers, reducing BOM count and layout complexity. |
| Leading-edge PFC + trailing-edge PWM | Minimizes conduction overlap between boost and forward switches, reducing ripple current in bulk output capacitor by >30% vs. dual leading-edge. |
| Programmable soft-start (SS2) | Externally timed capacitor charge/discharge enables controlled, low-stress turn-on of second stage only after PFC reaches regulation. |
| Feedforward line regulation (VFF) | Eliminates high-voltage components and reduces external parts count by deriving RMS line voltage from IAC current mirror + RC filter. |
| Zero-power detection | Monitors VAOUT to disable outputs when boost output falls below 0.33 V, preventing idle power draw and improving no-load efficiency. |
Applications
| Server Power Supply | Industrial AC-DC Adapter |
|---|---|
|
Use Scenario: 100-W universal-input (85–265 VRMS) offline power supply for rack-mounted server management modules. IC Role / Device Role / Timing Role: UCC38501DWTR performs PFC pre-regulation and isolated forward converter control with synchronized start-up and feedforward line regulation. Use Value: Achieves >95% PFC efficiency and >85% DC-DC efficiency while meeting EN61000-3-2 Class A harmonic limits and supporting 16-ms hold-up time. |
Use Scenario: DIN-rail mounted 48-V/5-A industrial power supply powering PLC I/O modules in factory automation. IC Role / Device Role / Timing Role: UCC38501DWTR manages boost PFC stage and forward converter with robust UVLO2 shutdown at 74% bulk voltage to prevent transformer core saturation during brownouts. Use Value: Enables reliable operation across wide ambient temperatures (0°C–70°C) and input sags down to 85 VRMS, with integrated OVP/ENBL disabling both stages on overvoltage. |
| Medical Equipment PSU | LED Driver Power Stage |
|
Use Scenario: Safety-certified 120-W AC-DC power supply for portable diagnostic imaging devices requiring low EMI and high reliability. IC Role / Device Role / Timing Role: UCC38501DWTR provides coordinated PFC and forward converter control with leading/trailing-edge modulation to reduce conducted EMI peaks. Use Value: Reduces bulk capacitor ripple current by minimizing switch overlap, lowering capacitor temperature rise and extending lifetime under continuous 24/7 operation. |
Use Scenario: High-efficiency 150-W constant-current LED driver for commercial lighting fixtures with universal AC input. IC Role / Device Role / Timing Role: UCC38501DWTR regulates boost PFC output and drives forward converter primary side, with VERR accepting secondary-side current feedback via optocoupler. Use Value: Supports precise constant-current regulation via secondary-side sensing while maintaining >0.99 power factor and <10% THD across full dimming range. |
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 |
|---|---|---|---|
| UCC28501DW | Same pinout and function; wider temperature grade (–40°C to 85°C) and higher VCC UVLO (16.5 V/10 V) for bootstrap bias operation. | Suitable for designs requiring extended ambient range or self-biased startup; not drop-in due to different UVLO thresholds and bias requirements. | Select UCC28501DW if operating below 0°C or using bootstrap VCC; UCC38501DWTR is preferred for fixed-bias, cost-sensitive 0°C–70°C applications. |
| UCC38502DWTR | Identical package and pinout; wider second-stage UVLO2 range (50% bulk voltage trip) and 3.0-V hysteresis vs. 1.2 V in UCC38501DWTR. | Enables deeper brownout tolerance before second-stage shutdown; trades tighter regulation stability for extended hold-up capability. | Choose UCC38502DWTR for applications needing sustained operation during severe line sags; UCC38501DWTR offers better regulation stability at nominal line. |
Compared with UCC28501DW and UCC38502DWTR, the UCC38501DWTR provides optimal balance of fixed-bias simplicity, tight UVLO2 regulation margin, and cost-effective 0°C–70°C operation-making it ideal for commercial-grade AC-DC supplies where startup reliability and thermal derating are less critical than BOM cost and layout compactness.
Availability
UCC38501DWTR is available at Aetrix Electronics and suitable for server power supplies, industrial AC-DC adapters, and medical equipment PSUs requiring stable component supply, long-term lifecycle support, and traceable sourcing for production programs.
Supply support for UCC38501DWTR 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 decades of expertise in high-reliability power conversion ICs.
The UCC3850x family was designed specifically for cost-sensitive, high-efficiency two-stage AC-DC power supplies-integrating PFC and PWM control to eliminate discrete controller duplication while enabling universal-input operation with minimal external components.
FAQ
What is the operating temperature range for the UCC38501DWTR?
The UCC38501DWTR is specified for operation from 0°C to 70°C ambient temperature. Its electrical characteristics-including 7.5-V reference accuracy (±12 mV), oscillator frequency (80–120 kHz), and UVLO thresholds-are guaranteed across this range. It is not rated for industrial (–40°C to 85°C) or automotive temperature grades.
How does the UCC38501DWTR implement feedforward line regulation?
The UCC38501DWTR generates feedforward via the IAC and VFF pins: IAC accepts a current proportional to instantaneous line voltage, which is mirrored 2:1 to VFF. An external RC filter converts this into a DC voltage proportional to line voltage squared, enabling constant input power regulation across 85–265 VRMS inputs without high-voltage components.
What is the purpose of the OVP/ENBL pin on the UCC38501DWTR?
The OVP/ENBL pin on the UCC38501DWTR serves dual functions: it disables the PFC gate driver (GT1) when boost output exceeds +6.67% of nominal voltage, and it disables both GT1 and GT2-and discharges SS2-when pulled below 1.9 V, providing coordinated shutdown for overvoltage or system enable control.
Can the UCC38501DWTR be used with a flyback converter instead of a forward topology?
The UCC38501DWTR is optimized for forward or half-bridge DC-DC topologies requiring transformer reset; its 50% maximum duty cycle on GT2 and VERR clamp are designed for this. While flyback use is possible with external modifications, TI does not characterize or recommend UCC38501DWTR for flyback-UCC28063 or UCC28780 are better suited.
What external components define the oscillator frequency of the UCC38501DWTR?
The oscillator frequency of the UCC38501DWTR is set by an external resistor (RT) from pin 2 to GND and a capacitor (CT) from pin 5 to GND, per the formula f = 0.725/(RT × CT). With RT = 22 kΩ and CT = 330 pF, typical frequency is 100 kHz; values must stay within 10 kΩ–100 kΩ for RT and ≥100 pF for CT to ensure stability.
UCC38501DWTR 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:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
UCC38501DWTR FAQ
1.How can I place an order for UCC38501DWTR through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC38501DWTR 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 UCC38501DWTR reliable?
The price and inventory of UCC38501DWTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC38501DWTR is usually 5 days.
3.What payment methods are accepted for UCC38501DWTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC38501DWTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC38501DWTR?
UCC38501DWTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC38501DWTR 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 UCC38501DWTR?
For technical support, including UCC38501DWTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC38501DWTR requirements.
6.How does Aetrix verify that UCC38501DWTR is sourced from the original manufacturer or authorized distributors?
All UCC38501DWTR 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 UCC38501DWTR meets industry standards.
7.What is the process for return or replacement of UCC38501DWTR?
All UCC38501DWTR units undergo pre-shipment inspection (PSI). If there is an issue with UCC38501DWTR, 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 UCC38501DWTR part is unused and in its original packaging.
Return procedure for UCC38501DWTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
UCC38501DWTR 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…
