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Texas Instruments UCC3818DWTR
- Part No.:
- UCC3818DWTR
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
UCC3818DWTR.pdf
- Description:
- IC PFC CTR AVERAGE 220KHZ 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,844
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Product details
Overview
UCC3818DWTR from Texas Instruments is a BiCMOS active power factor correction (PFC) controller for boost preregulators, implementing average current-mode control to achieve near-unity power factor and low line-current distortion. It operates from 10.2 V to 17 V VCC, features a 7.5-V internal reference, 10.5 V/10 V UVLO threshold, and supports up to 220 kHz switching frequency in PC power supplies and IEC61000-3-2-compliant <300 W industrial AC-DC systems.
For engineers reviewing the UCC3818DWTR datasheet, UCC3818DWTR pinout, UCC3818DWTR application, or UCC3818DWTR equivalent, this page delivers verified technical context, confirmed pin functions, real-world PFC design constraints, and validated alternative options for unity-power-factor preregulator implementations.
Technical Context
The UCC3818DWTR integrates a high-accuracy 7.5-V reference, dual error amplifiers (voltage and current), an analog multiplier with feed-forward (VFF) input, and a totem-pole gate driver delivering up to 1.2 A peak sink current. Its average current-mode architecture uses CAI/MOUT differential sensing and leading-edge PWM modulation to minimize bulk capacitor ripple.
UVLO is set at 10.5 V turn-on / 9.7 V turn-off with only 0.5 V hysteresis; OVP/EN provides windowed overvoltage protection with 1.9 V enable threshold and 500 mV hysteresis. The oscillator frequency is programmable via RT (10–100 kΩ) and CT, yielding 6–220 kHz per f ≈ 0.6/(RT × CT).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Operating Range | 10.2 V to 17 V - ensures reliable startup and operation across universal AC inputs after rectification and bulk capacitance. |
| UVLO Threshold | 10.5 V (turn-on) / 9.7 V (turn-off) - narrow hysteresis enables stable brownout recovery in 85–265 VAC systems. |
| Reference Voltage | 7.5 V ±12 mV (−40°C to +85°C) - precision reference for voltage amplifier biasing and peripheral circuitry. |
| Gate Driver Sink/Source | 1.2 A sink / ~900 mA source - drives MOSFET gates directly without external buffers in ≤300 W boost stages. |
| Oscillator Frequency Range | 6 kHz to 220 kHz - selectable via RT/CT to optimize EMI, efficiency, and magnetics size for target output power. |
| Current Amplifier Offset | ±2.5 mV max - minimizes light-load current-sense error, preserving THD compliance under partial load. |
| Soft-Start Charge Current | −10 µA typical - controls ramp rate of SS pin voltage to limit inrush current during power-up. |
Pinout & Package
UCC3818DWTR is housed in a 16-pin SOIC (DW) package measuring 7.5 mm × 10.3 mm, optimized for thermal dissipation and PCB layout density in compact AC-DC front-ends.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1) | Power and signal reference | Common return for VCC, VREF, and all analog blocks; requires direct 0.1 µF ceramic bypass to minimize noise coupling. |
| PKLMT (2) | Peak current limit input | Accepts level-shifted sense voltage; triggers shutdown when falling below 0 V - sets maximum switch current in boost inductor. |
| CAOUT (3) | Current amplifier output | Drives PWM comparator; compensation network between CAOUT and MOUT sets loop stability for average current control. |
| CAI (4) | Current amplifier non-inverting input | Connects to ground side of current-sense resistor; supports sub-GND operation for accurate zero-crossing detection. |
| MOUT (5) | Multiplier output / current amp inverting input | High-impedance node combining multiplier current and CAI feedback - enables differential sensing and leading-edge modulation. |
| IAC (6) | Line-voltage proportional current input | Accepts up to 500 µA from resistive divider off rectified AC - defines instantaneous line shape for multiplier-based current shaping. |
| VAOUT (7) | Voltage error amplifier output | Regulates DC bus voltage; clamped at ~5.5 V to prevent overshoot during transients or open-loop faults. |
| VFF (8) | Feed-forward RMS voltage | Generated by mirroring half IAC through RC filter; scales multiplier gain with line voltage to maintain constant power limit. |
| VREF (9) | 7.5-V precision reference output | Supplies 20 mA; disabled below UVLO - used for biasing sense networks and external circuitry requiring stable reference. |
| OVP/EN (10) | Overvoltage/enable window comparator | Pulls below 1.9 V to disable driver and discharge SS; monitors boosted output via resistor divider for fault protection. |
| VSENSE (11) | Voltage amplifier inverting input | Connected to output divider; forms feedback loop with VAOUT to regulate 380–400 V DC bus within ±1%. |
| RT (12) | Oscillator timing current input | Sets charging current for CT capacitor; 22 kΩ yields ~100 kHz - determines switching frequency and EMI profile. |
| SS (13) | Soft-start control | Charged by internal current source; ramps VAOUT-equivalent voltage to limit initial duty cycle and inrush current. |
| CT (14) | Oscillator timing capacitor | 270 pF to GND sets frequency with RT; short trace required to minimize jitter and parasitic coupling. |
| VCC (15) | Supply input | Must deliver ≥20 mA; bypassed locally to GND to support gate-drive current spikes without droop. |
| DRVOUT (16) | Boost switch gate driver | Totem-pole output driving N-channel MOSFET; series gate resistor (≥11 Ω @ 18 V) prevents ringing and overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Average current-mode control | Enables stable, low-THD sinusoidal line current draw across universal AC inputs without slope compensation. |
| Leading-edge PWM modulation | Reduces RMS ripple current in bulk electrolytic capacitors by synchronizing switch turn-on with inductor current zero-crossing. |
| Integrated 7.5-V reference | ±0.16% accuracy over temperature supports precise voltage regulation and eliminates need for external reference IC. |
| Feed-forward line voltage scaling (VFF) | Compensates multiplier gain for AC line variations, maintaining constant power limit and improving light-load regulation. |
| Low start-up current (150 µA typ) | Minimizes auxiliary supply burden during initial power-up, enabling simpler, lower-cost bias winding designs. |
| Overvoltage protection with hysteresis | 500 mV hysteresis on OVP/EN prevents oscillation during marginal overvoltage events while ensuring fast shutdown. |
Applications
| PC Power Supply | Industrial AC-DC Converter |
|---|---|
Use Scenario: 200–300 W ATX power supply complying with IEC61000-3-2 Class D limits. IC Role / Device Role / Timing Role: Primary PFC controller regulating boost stage to shape input current waveform matching AC voltage phase. Use Value: Enables >0.99 power factor and <10% THD at full load using single-stage boost topology with minimal external components. |
Use Scenario: DIN-rail mounted 240 W industrial power module operating from 85–265 VAC with wide temperature range. IC Role / Device Role / Timing Role: Active PFC front-end controller managing energy transfer into 380 V DC bus for downstream isolated DC-DC converters. Use Value: Supports −40°C to +85°C operation (UCC3818 spec), maintains regulation stability under line sags and surges common in factory environments. |
| LED Driver Front-End | Consumer Electronics Adapter |
Use Scenario: High-efficiency 150 W LED streetlight driver requiring Class C harmonic compliance. IC Role / Device Role / Timing Role: Boost PFC controller feeding constant-current LED string via secondary LLC resonant converter. Use Value: Reduces RMS current stress on bulk capacitor by 35% via leading-edge modulation, extending lifetime in thermally constrained outdoor enclosures. |
Use Scenario: Compact 90 W laptop adapter meeting ENERGY STAR Tier 2 and CoC v5 efficiency requirements. IC Role / Device Role / Timing Role: Integrated PFC controller enabling single-stage AC-DC conversion with adaptive frequency foldback. Use Value: Achieves >90% efficiency at 50% load using BiCMOS process, minimizing no-load power consumption (<300 mW) and heat generation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar active PFC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC2818DWTR | Same pinout, but rated for −40°C to +85°C; UVLO = 10.5 V/9.7 V; identical functional block diagram and electrical specs except temp range. | Supports extended industrial temperature range; suitable where ambient exceeds 70°C or cold-start reliability is critical. | Select UCC2818DWTR if system must operate continuously at −40°C or above 70°C ambient. |
| L6562ATDTR | SO-8 package (8-pin), fixed 65 kHz frequency, no integrated VREF or feed-forward; requires external reference and lacks VFF pin. | Lower BOM cost for basic PFC; limited to fixed-frequency designs without line-voltage feed-forward compensation. | Choose L6562ATDTR only for cost-sensitive, fixed-line applications where VFF-based power limiting is not required. |
Compared with UCC2818DWTR and L6562ATDTR, the UCC3818DWTR offers guaranteed −40°C to +85°C operation and integrated feed-forward scaling - making it uniquely suited for industrial and high-reliability PFC designs where line-voltage variation and temperature extremes demand tighter control.
Availability
UCC3818DWTR is available at Aetrix Electronics and suitable for PC power supplies, industrial AC-DC converters, and LED driver front-ends requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for safety-critical power systems.
Supply support for UCC3818DWTR 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 ICs.
The UCC3818DWTR belongs to TI's UCCx81x family of BiCMOS PFC controllers, designed specifically for high-efficiency, low-distortion boost preregulators in universal-input AC-DC power supplies up to 300 W.
FAQ
What is the operating temperature range for the UCC3818DWTR?
The UCC3818DWTR is specified for operation from −40°C to +85°C ambient temperature, as confirmed in the Electrical Characteristics table (TA = −40°C to 85°C). This extended range distinguishes it from the UCC2818DWTR (−40°C to +85°C) and UCC3817 variants (0°C to +70°C), making the UCC3818DWTR suitable for industrial and outdoor power applications where thermal margins are critical. All key parameters - including reference voltage, UVLO thresholds, and amplifier offsets - are guaranteed across this full range.
Does the UCC3818DWTR support leading-edge modulation, and how is it implemented?
Yes, the UCC3818DWTR implements leading-edge modulation via its MOUT/CAI differential current-sense architecture and synchronized PWM latch. As described in Section 7.3.5.7, the multiplier output current flows into MOUT, which serves as the inverting input of the current amplifier - enabling precise zero-current detection and switch turn-on at inductor current zero-crossing. This reduces RMS ripple in the bulk capacitor and improves reliability in high-power-density designs.
What is the purpose of the VFF pin on the UCC3818DWTR, and how does it affect power limiting?
The VFF pin on the UCC3818DWTR provides a feed-forward voltage proportional to the RMS line voltage, generated by mirroring half the IAC current through an external RC filter. As stated in Pin Function 8 and Section 7.3.5.14, VFF scales the analog multiplier's gain to maintain constant power limit across line variations - e.g., at low line (85 VAC), VFF ≈ 1.4 V, while at high line (265 VAC), VFF ≈ 4.7 V. This ensures consistent peak current limiting and stable regulation without manual gain adjustment.
Can the UCC3818DWTR be used without the SS (soft-start) capacitor?
No - the UCC3818DWTR requires an external capacitor on the SS pin for controlled startup. Per Section 7.3.5.11, SS is charged by an internal −10 µA current source; grounding SS does not force 0% duty cycle and may cause uncontrolled inrush. A typical 100 nF capacitor yields ~100 ms soft-start time. Omitting the capacitor risks overcurrent tripping, MOSFET failure, or bulk capacitor stress due to abrupt duty-cycle ramping during power-up.
What is the recommended minimum gate resistor for DRVOUT when driving a 1.2 A MOSFET gate?
The UCC3818DWTR datasheet specifies a recommended minimum gate resistance of 11 Ω for VCC = 18 V and IMAX = 1.2 A sink current, derived from Equation 5: RGATE = (VCC × Rpulldown) / IMAX. With typical pulldown resistance of 4 Ω, this value prevents excessive overshoot and ringing when driving capacitive MOSFET gates. Using less than 11 Ω risks shoot-through, EMI, and gate driver thermal stress - especially with fast-switching SiC or GaN devices.
UCC3818DWTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Mode:
- Average Current
- Frequency - Switching:
- 6kHz ~ 220kHz
- Current - Startup:
- 150 µA
- Voltage - Supply:
- 12V ~ 17V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
UCC3818DWTR FAQ
1.How can I place an order for UCC3818DWTR through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC3818DWTR 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 UCC3818DWTR reliable?
The price and inventory of UCC3818DWTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC3818DWTR is usually 5 days.
3.What payment methods are accepted for UCC3818DWTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC3818DWTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC3818DWTR?
UCC3818DWTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC3818DWTR 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 UCC3818DWTR?
For technical support, including UCC3818DWTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC3818DWTR requirements.
6.How does Aetrix verify that UCC3818DWTR is sourced from the original manufacturer or authorized distributors?
All UCC3818DWTR 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 UCC3818DWTR meets industry standards.
7.What is the process for return or replacement of UCC3818DWTR?
All UCC3818DWTR units undergo pre-shipment inspection (PSI). If there is an issue with UCC3818DWTR, 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 UCC3818DWTR part is unused and in its original packaging.
Return procedure for UCC3818DWTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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