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Texas Instruments UCC38501DW
- Part No.:
- UCC38501DW
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
UCC38501DW.pdf
- Description:
- IC PFC CTR AVERAGE 100KHZ 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,125
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Product details
Overview
UCC38501DW from Texas Instruments is a dual-stage active 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 100 kHz oscillator frequency, 7.5 V reference accuracy ±12 mV, and synchronized leading-edge (PFC) / trailing-edge (DC-DC) modulation for reduced bulk-capacitor ripple. Used in universal-input AC-DC front-end supplies for industrial power systems.
For engineers reviewing the UCC38501DW datasheet, UCC38501DW pinout, UCC38501DW application, or UCC38501DW equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters across temperature (0°C to 70°C), and real-world design implications for PFC+DC-DC coordination, soft-start sequencing, and feedforward line regulation.
Technical Context
The UCC38501DW implements a two-stage control architecture: the PFC section uses average current-mode control with a high-linearity analog multiplier (K = 0.5–1.5 V⁻¹), IAC-based RMS feedforward (VFF), and zero-power detection (0.175–0.5 V VAOUT threshold); the DC-DC stage employs external error amplification fed via VERR, peak-current sensing on ISENSE2, and 50% maximum duty cycle clamping.
It features narrow UVLO thresholds (10.5 V turn-on / 9.7 V turn-off) optimized for fixed-bias operation, synchronized start-up where the second stage enables only after PFC output reaches ≥90% nominal voltage, and internal protection including PFC overvoltage (OVP/ENBL window comparator), PFC peak current limiting (PKLMT at 0 V threshold), and second-stage pulse-by-pulse current limit (1.05 V typical threshold on ISENSE2).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 100 kHz typical; programmable via RT/CT; ±15 kHz total variation over line/temp ensures stable timing in universal-input designs. |
| Voltage Reference (VREF) | 7.500 V ±12 mV (0°C–70°C); supplies bias for external circuits and level-shifting networks; short-circuit protected to 50 mA. |
| PFC Gate Driver (GT1) | 100 mA sink/source; 5–12 Ω pull-up/pull-down resistance; 25–50 ns rise/fall times enable direct MOSFET drive without external buffers. |
| Second-Stage Gate Driver (GT2) | 100 mA sink/source; 5–12 Ω pull-up/pull-down; 50% max duty cycle enforced internally to guarantee transformer reset in forward topologies. |
| UVLO Thresholds | 10.5 V turn-on / 9.7 V turn-off (narrow hysteresis 0.3–0.5 V); designed for fixed 12 V bias supply, not bootstrap operation. |
| Zero-Power Detection | Active when VAOUT falls below 0.33 V (0.175–0.5 V range); disables PFC output to eliminate no-load consumption in standby mode. |
| Feedforward Signal (VFF) | Generated from IAC mirror + external RC filter; scales from 1.4 V (low line) to 4.7 V (high line); enables constant input power over 3:1 input voltage range. |
Pinout & Package
UCC38501DW is housed in a 20-pin SOIC (DW) package with 0.3" body width and standard 0.050" pitch; RoHS-compliant, tape-and-reel available (TR suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VAOUT | Voltage amplifier output | Regulates PFC output voltage; clamped to ~5.5 V to prevent overshoot; drives multiplier and sets PFC current reference. |
| RT | Oscillator charging current source | Sets oscillator frequency with CT; 22 kΩ nominal value yields 100 kHz; operates at ~3 V bias. |
| VSENSE | PFC voltage error amplifier inverting input | Connects to output divider network; forms feedback loop with VAOUT for boost output regulation. |
| OVP/ENBL | PFC overvoltage/enable control | Window comparator: disables PFC if boost exceeds +6.67%, disables both stages if pulled below 1.9 V. |
| CT | Oscillator timing capacitor node | Capacitor to GND sets frequency per f ≈ 0.725/(RT × CT); requires short, low-inductance GND path. |
| GND | Analog ground reference | Common return for VCC/VREF bypass caps; carries oscillator discharge current; separate from PWRGND. |
| VERR | DC-DC error signal input | Accepts opto-coupled secondary-side error signal; 4.5 V internal clamp limits GT2 duty cycle to ≤50%. |
| ISENSE2 | DC-DC peak current sense input | Receives current-sense resistor voltage; triggers pulse-by-pulse shutdown at 1.05 V threshold; supports slope compensation. |
| VCC | Positive supply input | 12–17 V operation; requires ≥20 mA supply; inhibited until UVLO threshold exceeded; bypass with ≥0.1 µF ceramic. |
| GT2 | DC-DC gate driver output | Drives downstream PWM switch (e.g., forward converter primary); limited to 50% max duty cycle for safe reset. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated PFC + DC-DC control | Eliminates need for two separate controllers; reduces BOM count and PCB area in 2-stage AC-DC supplies. |
| Leading-edge PFC / trailing-edge DC-DC sync | Minimizes overlap conduction between boost and PWM switches, reducing RMS ripple current in bulk output capacitor by up to 40%. |
| Programmable soft-start (SS2) | Internal current source charges external SS2 cap; controls ramp-up of DC-DC duty cycle to limit inrush stress during PFC stabilization. |
| Line feedforward (VFF) | Derived from IAC mirror + single-pole RC filter; maintains constant input power across 85–265 VAC without high-voltage components. |
| Zero-power detection | Monitors VAOUT; shuts down PFC when output drops below 0.33 V, enabling <300 µA no-load supply current. |
| UVLO with narrow hysteresis | 10.5 V/9.7 V thresholds match fixed 12 V bias rails; avoids false triggering during brownout or startup transients. |
Applications
| Industrial AC-DC Power Supplies | Medical Equipment Power Front-Ends |
|---|---|
|
Use Scenario: Universal-input (85–265 VAC), 100–500 W offline power supply feeding isolated DC-DC stage. IC Role / Device Role / Timing Role: UCC38501DW performs PFC regulation and synchronizes downstream PWM timing to minimize conduction overlap and bulk-capacitor stress. Use Value: Achieves >0.99 power factor at full load; reduces hold-up capacitor size by 25% via lower RMS ripple current. |
Use Scenario: Safety-critical medical power system requiring low EMI, tight output regulation, and reliable standby behavior. IC Role / Device Role / Timing Role: UCC38501DW enforces coordinated start-up (DC-DC enabled only after PFC reaches 90% output) and zero-power shutdown for IEC 60601 compliance. Use Value: Eliminates unregulated DC-DC operation during PFC soft-start; reduces no-load consumption to <300 µA. |
| Telecom Rectifier Modules | Server PSU Front-Ends |
|
Use Scenario: High-density 48 V telecom rectifier with wide input range and strict THD limits. IC Role / Device Role / Timing Role: UCC38501DW implements average-current-mode PFC with feedforward (VFF) to maintain constant power across line variations. Use Value: Meets EN 61000-3-2 Class A THD requirements at 100% load; supports 3:1 input voltage range without re-tuning. |
Use Scenario: 80 PLUS Titanium-certified server PSU requiring high efficiency (>96%) and precise PFC/DC-DC coordination. IC Role / Device Role / Timing Role: UCC38501DW integrates PFC and DC-DC control logic, enabling interleaved or phase-shifted operation via external synchronization. Use Value: Enables <1% output voltage deviation under dynamic load steps via fast PFC response and controlled DC-DC soft-start. |
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 | Wider temperature range (–40°C to 85°C) vs. UCC38501DW (0°C to 70°C); identical pinout, UVLO (10.5 V/9.7 V), and functional blocks. | Required for extended-temperature industrial or outdoor deployments; UCC38501DW is cost-optimized for commercial-grade equipment. | Select UCC28501DW if ambient operating temperature may fall below 0°C or exceed 70°C. |
| UCC38502DW | Wider second-stage UVLO2 (6.3–7.3 V turn-on, 2.4–3.6 V hysteresis) vs. UCC38501DW's narrow UVLO2 (6.3–7.3 V, 0.96–1.44 V hysteresis); same PFC UVLO. | Supports deeper PFC output droop (down to 50% nominal) before disabling DC-DC stage; UCC38501DW disables at 74% nominal. | Choose UCC38502DW for applications needing robust hold-up during brownouts; UCC38501DW prioritizes tighter regulation stability. |
Compared with UCC28501DW, UCC38501DW trades extended temperature capability for lower cost in commercial environments; compared with UCC38502DW, it provides stricter DC-DC disable threshold for improved output regulation fidelity during marginal line conditions.
Availability
UCC38501DW is available at Aetrix Electronics and suitable for industrial AC-DC power supplies, medical equipment front-ends, and telecom rectifier modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for UCC38501DW 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 power conversion IC design.
The UCC3850x family was engineered specifically for cost-sensitive, high-efficiency two-stage AC-DC conversion-integrating PFC and DC-DC control in a single IC to reduce system complexity and improve reliability in commercial and industrial power supplies.
FAQ
What is the operating temperature range for the UCC38501DW?
The UCC38501DW is specified for operation from 0°C to 70°C ambient temperature. This commercial-grade range aligns with its narrow UVLO thresholds (10.5 V/9.7 V) and fixed-bias design intent. For extended-temperature applications (–40°C to 85°C), the functionally identical UCC28501DW is recommended. All electrical characteristics in the SLUS419C datasheet are validated within this 0°C–70°C range.
How does the UCC38501DW coordinate start-up between the PFC and DC-DC stages?
The UCC38501DW monitors the PFC output voltage via VAOUT and holds the DC-DC stage disabled until VAOUT reaches ≥90% of nominal regulation. Once triggered, SS2 initiates a controlled soft-start ramp for GT2. If VAOUT later drops below 74% of nominal (UCC38501DW-specific threshold), the DC-DC stage shuts down-preventing overstress during brownout. This sequencing is fully internal and requires no external logic.
What is the purpose of the VFF pin on the UCC38501DW?
The VFF pin on the UCC38501DW provides RMS line-voltage feedforward derived from an IAC current mirror and external RC filter. It scales from ~1.4 V at low line (85 VAC) to ~4.7 V at high line (265 VAC), enabling the multiplier to maintain constant input power across a 3:1 input voltage range-reducing component count and eliminating high-voltage sensing circuitry.
Can the UCC38501DW be used with a flyback DC-DC topology?
No-the UCC38501DW is optimized for transformer-isolated forward or half-bridge DC-DC topologies where the secondary-side error signal is fed back via optocoupler to VERR. Its 50% maximum duty cycle clamp and peak-current sensing on ISENSE2 assume a reset mechanism requiring controlled off-time; flyback operation violates this constraint and risks transformer saturation.
What is the function of the PKLMT pin on the UCC38501DW?
The PKLMT pin on the UCC38501DW sets the PFC stage's peak current limit threshold. It accepts a level-shifted voltage referenced to VREF (7.5 V), where 0 V at PKLMT corresponds to the current limit trip point. A resistor divider from the current-sense resistor's negative terminal to VREF configures the exact overcurrent threshold, protecting the boost switch during fault conditions.
UCC38501DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- 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
UCC38501DW FAQ
1.How can I place an order for UCC38501DW through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC38501DW 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 UCC38501DW reliable?
The price and inventory of UCC38501DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC38501DW is usually 5 days.
3.What payment methods are accepted for UCC38501DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC38501DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC38501DW?
UCC38501DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC38501DW 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 UCC38501DW?
For technical support, including UCC38501DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC38501DW requirements.
6.How does Aetrix verify that UCC38501DW is sourced from the original manufacturer or authorized distributors?
All UCC38501DW 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 UCC38501DW meets industry standards.
7.What is the process for return or replacement of UCC38501DW?
All UCC38501DW units undergo pre-shipment inspection (PSI). If there is an issue with UCC38501DW, 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 UCC38501DW part is unused and in its original packaging.
Return procedure for UCC38501DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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