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Texas Instruments UCC3818N
- Part No.:
- UCC3818N
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
UCC3818N.pdf
- Description:
- IC PFC CTR AV CURR 220KHZ 16DIP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
UCC3818N 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 precision reference, 10.5 V/10 V UVLO threshold, and supports 6–220 kHz switching frequency via RT/CT programming. Used in sub-300 W IEC61000-3-2-compliant AC-DC supplies.
For engineers reviewing the UCC3818N datasheet, UCC3818N pinout, UCC3818N application, or UCC3818N equivalent, key selection considerations include its UVLO hysteresis (0.3–0.5 V), peak current limit architecture (PKLMT input referenced to 0 V), soft-start current (−6 to −16 µA), gate driver pullup/pulldown resistance (5–12 Ω / 2–10 Ω), and feed-forward voltage (VFF) behavior at low line (1.4 V).
Technical Context
The UCC3818N integrates an analog multiplier with three inputs-VAOUT (voltage error signal), IAC (line-voltage-proportional current), and VFF (feed-forward RMS voltage)-to generate IMOUT for average current-mode control. Its zero-power comparator triggers at 0.33 V on VAOUT to latch off DRVOUT during no-load conditions.
It employs leading-edge PWM modulation synchronized to the boost switch's turn-on edge, reducing bulk capacitor ripple current. The internal 7.5 V reference supplies 20 mA and is disabled below UVLO; CAOUT drives the current amplifier with wide bandwidth to maintain low distortion across load and line variations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC UVLO Turn-On/Off | 10.2 V / 9.7 V - enables operation only within stable supply range; 0.5 V hysteresis prevents chatter during brownout |
| VREF Output | 7.5 V ±12 mV (−40°C to 85°C) - powers external circuitry and sets PKLMT scaling; short-circuit protected to −50 mA |
| Oscillator Frequency Range | 6–220 kHz - set by RT (10–100 kΩ) and CT; initial accuracy ±15% at 25°C ensures predictable timing |
| Gate Driver Output | Pullup 5–12 Ω / Pulldown 2–10 Ω - delivers >1 A peak sink/source to drive MOSFET gates directly; rise/fall <50 ns into 1 nF |
| Current Amplifier Offset | ±2.5 mV max - minimizes light-load current sensing error, preserving THD performance below 10% load |
| OVP/EN Threshold | Enable: 1.9 V typ; OVP trip: VREF + 0.50 V - provides programmable overvoltage shutdown with 500 mV hysteresis |
| Soft-Start Charge Current | −10 µA typ - linearly ramps SS voltage to control duty-cycle ramp-up, preventing inrush during startup |
Pinout & Package
UCC3818N is housed in a 16-pin PDIP package (6.35 mm × 19.3 mm body size) with through-hole mounting and standard lead pitch. Thermal resistance RθJA = 49.3°C/W on JEDEC-standard board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1) | Reference ground | All internal voltages referenced here; requires direct 0.1 µF ceramic bypass to VCC/VREF |
| PKLMT (2) | Peak current limit input | Sense resistor divider output; triggers limit when voltage falls below 0 V (not threshold-based) |
| CAOUT (3) | Current amplifier output | Drives compensation network between CAOUT and MOUT; wide bandwidth enables fast current loop response |
| CAI (4) | Current amp noninverting input | Connected to GND-side of sense resistor; functional down to −0.5 V for bidirectional sensing |
| MOUT (5) | Multiplier output / CA inverting input | High-impedance node combining multiplier current and CA feedback; enables differential configuration for noise immunity |
| IAC (6) | Line voltage proportional current input | Accepts up to 500 µA; scaled to match VFF and VAOUT for accurate power calculation in multiplier |
| VAOUT (7) | Voltage error amplifier output | Limited to 5.5 V max; feeds multiplier and zero-power comparator; open-loop gain ≥90 dB ensures tight regulation |
| VFF (8) | Feed-forward voltage input | RMS-derived signal (1.4 V at low line); compensates for line voltage variation in multiplier gain |
| VREF (9) | 7.5 V reference output | Stable, loadable reference for biasing, scaling, and PKLMT level-shifting; disabled below UVLO |
| OVP/EN (10) | Overvoltage/enable window comparator | Disables DRVOUT if boost voltage exceeds VREF+0.50 V; resets SS if pulled <1.9 V |
| VSENSE (11) | Voltage error amp inverting input | Connected to output divider; high-impedance (50–200 nA bias) minimizes loading on feedback network |
| RT (12) | Oscillator charging current input | Resistor to GND programs oscillator current; nominal 3 V bias enables precise frequency setting |
| SS (13) | Soft-start control | External capacitor charged at −10 µA; used as voltage error signal during startup to limit inrush |
| CT (14) | Oscillator timing capacitor | Capacitor to GND sets frequency per f ≈ 0.6/(RT×CT); short GND trace required for stability |
| VCC (15) | Power supply input | 10–17 V operating range; must deliver ≥20 mA; bypassed directly to GND for gate-drive transients |
| DRVOUT (16) | Boost switch gate driver output | Totem-pole MOSFET driver; requires series gate resistor (≥11 Ω typical) to damp overshoot into capacitive loads |
Key Features
| Feature | Design Value |
|---|---|
| Average current-mode control | Enables stable, low-distortion sinusoidal line current without slope compensation; supports CRM/CCM operation |
| Leading-edge PWM modulation | Reduces bulk capacitor ripple current by synchronizing switch turn-on with zero-current crossing, extending capacitor life |
| Accurate 7.5 V reference | ±12 mV tolerance over −40°C to +85°C; 20 mA drive capability eliminates need for external reference in most designs |
| Programmable overvoltage protection | VREF-referenced OVP threshold (VREF + 0.50 V) with 500 mV hysteresis ensures reliable shutdown without nuisance tripping |
| Zero-power detection | Comparator monitors VAOUT and latches DRVOUT low when VAOUT drops below 0.33 V, eliminating no-load power loss |
| Low start-up current | 150 µA typical - enables high-impedance VCC startup networks, reducing standby power consumption |
Applications
| PC Power Supplies | Consumer Electronics Adapters |
|---|---|
|
Use Scenario: 150–250 W ATX main power supply with universal AC input (90–264 VAC). IC Role / Device Role / Timing Role: Controls boost PFC stage to meet IEC61000-3-2 Class D harmonic limits; regulates DC bus at 385 V. Use Value: Achieves >0.99 power factor and <10% THD across full line/load range using average current sensing and feed-forward line regulation. |
Use Scenario: 65–120 W laptop adapter with active PFC front-end and flyback secondary. IC Role / Device Role / Timing Role: Implements critical conduction mode (CRM) PFC to minimize EMI filter size and improve efficiency at light loads. Use Value: Enables compact design with 92% peak efficiency and compliance to ENERGY STAR® Tier 2 requirements. |
| Industrial LED Drivers | Medical Power Modules |
|
Use Scenario: 200 W constant-current LED driver for street lighting with wide-input AC operation. IC Role / Device Role / Timing Role: Regulates boost output to 400 V DC while shaping input current to match sinusoidal voltage waveform. Use Value: Delivers consistent lumen output across 85–305 VAC input with <5% output ripple and 100,000-hour capacitor lifetime. |
Use Scenario: 100 W isolated medical-grade power supply requiring reinforced insulation and low leakage current. IC Role / Device Role / Timing Role: Provides PFC pre-regulation before isolated DC-DC conversion; supports 2 MOPP isolation schemes. Use Value: Meets IEC60601-1 creepage/clearance requirements while maintaining <300 µA earth leakage under all line conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar power factor correction controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC2818N | Same pinout and function; rated for −40°C to +85°C industrial temp range vs. UCC3818N's 0°C to +70°C | Preferred for extended-temperature industrial or outdoor deployments where ambient exceeds 70°C | Select UCC2818N when full industrial temperature range is required; otherwise UCC3818N offers identical performance at lower cost |
| ICE3PCS01G | Fixed-frequency CCM controller; no VFF input; integrated zero-crossing detector; different multiplier architecture | Better suited for cost-sensitive, fixed-line applications where feed-forward line regulation is not needed | Choose ICE3PCS01G for simplified BOM and lower gate count; UCC3818N remains superior for universal-input, low-THD designs |
Compared with UCC2818N, the UCC3818N trades extended temperature rating for lower cost and identical electrical specs; compared with ICE3PCS01G, it delivers tighter THD control and flexible frequency tuning but requires more external components for feed-forward implementation.
Availability
UCC3818N is available at Aetrix Electronics and suitable for PC power supplies, consumer electronics adapters, industrial LED drivers, and medical power modules requiring stable component supply and long-term manufacturability.
Supply support for UCC3818N 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 ICs, with decades of expertise in power conversion and energy-efficient design.
The UCC3818N belongs to TI's BiCMOS PFC controller product line, engineered specifically for high-efficiency, low-distortion active power factor correction in universal-input AC-DC power supplies up to 300 W.
FAQ
What is the operating temperature range of the UCC3818N?
The UCC3818N is specified for operation from 0°C to +70°C ambient temperature. This commercial-grade rating distinguishes it from the UCC2818N, which extends to −40°C to +85°C. All electrical characteristics-including reference voltage accuracy, UVLO thresholds, and oscillator frequency-are guaranteed across this 0°C to +70°C range. The UCC3818N uses BiCMOS process technology to achieve low power dissipation and stable performance within this envelope.
How does the UCC3818N implement overvoltage protection?
The UCC3818N implements overvoltage protection via the OVP/EN pin, which functions as a window comparator. When the voltage at OVP/EN exceeds VREF + 0.50 V (typical), the device disables DRVOUT to halt switching. The OVP threshold has 500 mV hysteresis to prevent oscillation near the trip point. Additionally, pulling OVP/EN below 1.9 V (typical) forces a full reset, discharging the SS capacitor and disabling both PFC output and PWM latch.
Can the UCC3818N be used in discontinuous conduction mode (DCM)?
Yes, the UCC3818N supports discontinuous conduction mode (DCM) operation through its average current-mode control architecture and leading-edge modulation. While optimized for critical conduction mode (CRM) and continuous conduction mode (CCM), the controller maintains stable current regulation and low THD in DCM by continuously adapting duty cycle based on sensed line current and feed-forward voltage. External RT/CT selection determines whether the design operates in DCM or CRM at light loads.
What is the purpose of the VFF pin on the UCC3818N?
The VFF (feed-forward voltage) pin on the UCC3818N provides a scaled RMS representation of the rectified AC line voltage, generated by mirroring half the IAC current into an external RC filter. At low line (90 VAC), VFF is 1.4 V; at high line (264 VAC), it reaches ~4.7 V. This signal dynamically adjusts the analog multiplier's gain to maintain constant power delivery and reduce line-voltage-induced current distortion-key to achieving IEC61000-3-2 compliance.
Does the UCC3818N require an external current-sense resistor on the high-side or low-side of the boost inductor?
The UCC3818N is designed for low-side current sensing: the CAI pin connects to the ground side of the current-sense resistor, and the PKLMT pin accepts a level-shifted signal derived from the same resistor's negative terminal referenced to VREF. This configuration allows the CAI and MOUT inputs to operate down to −0.5 V, supporting accurate sensing even during negative current transitions. High-side sensing is not supported by the UCC3818N's input architecture.
UCC3818N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- 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:
- Through Hole
- Supplier Device Package:
- 16-PDIP
UCC3818N FAQ
1.How can I place an order for UCC3818N through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC3818N 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 UCC3818N reliable?
The price and inventory of UCC3818N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC3818N is usually 5 days.
3.What payment methods are accepted for UCC3818N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC3818N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC3818N?
UCC3818N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC3818N 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 UCC3818N?
For technical support, including UCC3818N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC3818N requirements.
6.How does Aetrix verify that UCC3818N is sourced from the original manufacturer or authorized distributors?
All UCC3818N 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 UCC3818N meets industry standards.
7.What is the process for return or replacement of UCC3818N?
All UCC3818N units undergo pre-shipment inspection (PSI). If there is an issue with UCC3818N, 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 UCC3818N part is unused and in its original packaging.
Return procedure for UCC3818N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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