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Texas Instruments UC3854N-F
- Part No.:
- UC3854N-F
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
UC3854N-F.pdf
- Description:
- IC PFC CTR AV CURR 200KHZ 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,075
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Product details
Overview
UC3854N-F from Texas Instruments is a high-power-factor preregulator controller IC designed for active PFC in AC-DC front-end stages. It implements average current-mode control, features a 7.5V precision reference, 1A totem-pole gate driver, and analog multiplier/divider for line-current shaping - enabling >0.99 power factor and <5% line-current distortion in 250W boost preregulators operating from 80–260VRMS, 50–400Hz.
For engineers reviewing the UC3854N-F datasheet, UC3854N-F pinout, UC3854N-F application, or UC3854N-F equivalent, this page delivers verified technical context, real-world design parameters, validated pin functions, confirmed alternatives, and supply-chain support specific to the UC3854N-F PDIP-16 package with 0°C to 70°C temperature rating.
Technical Context
The UC3854N-F uses average current-mode control - not peak mode - eliminating need for slope compensation while maintaining sinusoidal line current and low noise sensitivity. Its internal analog multiplier divides line current by the square of VRMS to achieve feed-forward line regulation across 3:1 input voltage range (85–255VAC).
It integrates a voltage amplifier (70–100 dB gain, 0.5–5.8 V swing), current amplifier (80–110 dB gain, 0.5–16 V swing), fixed-frequency oscillator (46–118 kHz via RSET/CT), and 1A gate driver with 35 ns rise/fall time - all operating within its specified 0°C to 70°C ambient range and 35V absolute max VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Temperature | 0°C to 70°C - defines industrial-grade thermal envelope for stable PFC loop performance |
| Oscillator Frequency Range | 46–118 kHz - set by external RSET (8.2k–15kΩ) and CT capacitor; enables 100 kHz typical design |
| Voltage Reference | 7.5 V ±0.1 V - precision internal reference used for VSENSE regulation and SS soft-start ramp |
| Gate Driver Output | 1 A peak, 12.8 V high-level at –200 mA - drives MOSFET gates directly without external buffer in ≤250W designs |
| Multiplier Input Range | IAC: 0–400 µA; VRMS: 1.5–3.5 V - supports RMS-scaled feed-forward over full universal AC input range |
| Current Amplifier Bandwidth | 400–800 kHz - ensures fast line-current tracking with minimal phase lag in average-mode control loop |
| ENA Threshold | 2.55 V rising, 2.3 V falling - provides 250 mV hysteresis for reliable start-up sequencing and fault shutdown |
Pinout & Package
UC3854N-F is supplied in a 16-pin plastic dual in-line package (PDIP-N), RoHS-compliant, with through-hole mounting and 0.3-inch width. Lead finish is Cu/Ni/PdAu; MSL not applicable.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Gnd (Pin 1) | Signal and power ground reference | All voltages referenced here; timing capacitor return path; requires short, direct 0.1 µF ceramic bypass |
| PKLMT (Pin 2) | Peak current limit threshold input | 0 V threshold; connects to negative side of sense resistor; sets maximum switch current (e.g., 6 A with 0.25 Ω) |
| CA Out (Pin 3) | Current amplifier output | Drives PWM comparator; swings to near GND for zero-duty-cycle capability; remains active during disable |
| ISENSE (Pin 4) | Inverting current sense input | Accepts differential current-sense signal down to –0.5 V; used with Mult Out for noise-rejecting current loop |
| Mult Out (Pin 5) | Multiplier output / current sense non-inverting input | High-impedance current output; tied internally to ISENSE+; enables differential sensing and line-current shaping |
| IAC (Pin 6) | AC line voltage waveform input (current-mode) | Receives 0–400 µA current proportional to instantaneous line voltage; cancels crossover distortion when biased to REF |
| VA Out (Pin 7) | Voltage amplifier output | Regulates DC output voltage; limited to ~5.8 V; controls multiplier gain; stays active during ENA/VCC disable |
| VRMS (Pin 8) | RMS line voltage feed-forward input | 1.5–3.5 V input proportional to rectified line average; squared internally to normalize power vs. line variation |
| VREF (Pin 9) | 7.5 V precision reference output | Supplies 10 mA; disabled when VCC < 10 V or ENA low; requires 0.1 µF ceramic bypass to GND |
| ENA (Pin 10) | Enable logic input | 2.55 V turn-on threshold; releases SS clamp and enables REF/GT Drv/oscillator; hysteresis prevents chatter |
| VSENSE (Pin 11) | Voltage amplifier inverting input | 7.5 V threshold; connects to output divider (e.g., 400 V → 7.5 V via 53.3:1 ratio); 50 nA bias current |
| RSET (Pin 12) | Oscillator timing and multiplier limit set | Sets oscillator frequency (F = 1.25/(RSET × CT)) and max multiplier output (IMULTMAX = –3.75 V / RSET) |
| SS (Pin 13) | Soft-start timing node | Internally sourced –14 µA; charges external capacitor to ramp reference voltage slowly; discharges fast on fault |
| CT (Pin 14) | Oscillator timing capacitor connection | Connects to GND; sets PWM frequency with RSET; valley voltage 0.8–1.3 V, peak-to-valley 4.9–5.9 V |
| VCC (Pin 15) | Positive supply input | 14.5–17.5 V turn-on, 9–11 V turn-off; requires ≥20 mA supply and local 0.1 µF ceramic bypass |
| GT Drv (Pin 16) | Gate drive output | Totem-pole MOSFET driver; clamped to 15 V; 1 A peak; requires ≥5 Ω series gate resistor to prevent overshoot |
Key Features
| Feature | Design Value |
|---|---|
| Average current-mode control | Enables stable, distortion-free sinusoidal line current without slope compensation or external compensation networks |
| Feed-forward line regulation | Uses VRMS input to divide line current by VRMS², maintaining constant input power across 85–255 VAC range |
| Low-noise analog multiplier/divider | Supports <5% THD line current via precise IAC × VA Out / VRMS² computation with 1 V gain constant |
| Integrated 7.5 V reference & gate driver | Eliminates external reference IC and driver stage; 1 A peak drive supports MOSFETs up to 1 nF gate charge in 250W designs |
| Soft-start and peak-limit protection | SS pin enables controlled ramp-up; PKLMT pin provides cycle-by-cycle current limiting with 175 ns response to overcurrent |
Applications
| Industrial Motor Drive Front-End | Medical Imaging Power Supply |
|---|---|
Use Scenario: 3 kW AC-DC conversion for servo drive with strict IEC 61000-3-2 Class A harmonic limits. IC Role / Device Role / Timing Role: UC3854N-F acts as the active PFC controller in continuous-conduction-mode boost stage, synchronizing line current to voltage waveform via IAC/VRMS inputs. Use Value: Achieves 0.99 PF and <4.5% THD at full load, meeting Class A compliance without passive filters - reducing system size and EMI filter cost. | Use Scenario: 1.2 kW isolated power supply for CT scanner subsystem requiring ultra-low EMI and high reliability. IC Role / Device Role / Timing Role: UC3854N-F regulates boost output at 400 V DC while enforcing clean sinusoidal input current under varying line conditions (85–264 VAC). Use Value: Enables >92% system efficiency and eliminates 3rd/5th harmonic injection into facility wiring - critical for sensitive diagnostic equipment. |
| Telecom Rectifier Module | LED Streetlight Driver |
Use Scenario: 2.5 kW telecom rectifier operating in hot, unconditioned central office environments. IC Role / Device Role / Timing Role: UC3854N-F serves as the PFC controller in a two-stage architecture, interfacing with downstream LLC resonant converter. Use Value: Delivers stable 54 V output with 0.99 PF across –5°C to +55°C ambient, leveraging its 0°C to 70°C rating and low-startup current (2 mA off-state). | Use Scenario: Outdoor-rated 150 W LED driver for street lighting with universal AC input and surge immunity. IC Role / Device Role / Timing Role: UC3854N-F controls boost PFC stage feeding buck-boost DC-DC; operates with 100 kHz switching to minimize audible noise. Use Value: Maintains >0.98 PF across lifetime despite electrolytic capacitor aging, thanks to average-mode stability and VRMS feed-forward robustness. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar active power factor correction controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3854DW | SOIC-16 surface-mount package; identical electrical specs and 0°C to 70°C rating | Requires PCB re-layout for SMT assembly; better thermal dissipation in dense layouts | Select UC3854DW for automated manufacturing or space-constrained designs where through-hole is impractical |
| UC2854N | –40°C to +85°C extended temp range; otherwise pin- and function-compatible | Valid for wider ambient environments (e.g., outdoor enclosures, automotive charging systems) | Choose UC2854N when operation below 0°C or above 70°C is required; no circuit redesign needed |
Compared with UC3854N-F, UC3854DW offers identical functionality in SOIC-16 for SMT production, while UC2854N extends operational range to –40°C to +85°C - making it suitable for harsher environments without altering control loop design or component selection.
Availability
UC3854N-F is available at Aetrix Electronics and suitable for industrial motor drives, medical imaging power supplies, telecom rectifiers, and LED streetlight drivers requiring stable component supply and long-term obsolescence management.
Supply support for UC3854N-F 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.
The UC3854N-F belongs to TI's UCx854 family of active power factor correction controllers, engineered specifically for high-efficiency, low-distortion AC-DC front-end regulation in universal-input power supplies.
FAQ
What is the operating temperature range of the UC3854N-F?
The UC3854N-F is rated for 0°C to 70°C ambient operation. This industrial-grade temperature specification is explicitly defined in the Electrical Characteristics table and distinguishes it from the UC1854 (–55°C to 125°C) and UC2854 (–40°C to 85°C). All guaranteed parameters - including oscillator frequency, reference voltage accuracy, and amplifier gains - apply within this 0°C to 70°C range for the UC3854N-F.
Does the UC3854N-F support average current-mode control, and why does it matter?
Yes, the UC3854N-F implements average current-mode control - confirmed in its functional description and block diagram. This architecture eliminates the need for slope compensation, improves noise immunity versus peak current-mode, and enables accurate sinusoidal line-current tracking without distortion. For the UC3854N-F, this directly enables <5% line-current THD and 0.99 power factor in boost preregulator designs.
What is the purpose of the VRMS pin (Pin 8) on the UC3854N-F?
The VRMS pin on the UC3854N-F accepts a DC voltage (1.5–3.5 V) proportional to the RMS value of the AC line input. Internally, this signal is squared and used as a divisor in the analog multiplier to normalize line current demand across wide input voltage ranges. In the UC3854N-F, this feed-forward mechanism enables stable power factor correction from 85 VAC to 255 VAC without loop re-tuning.
Can the UC3854N-F drive a MOSFET gate directly, and what are the limits?
Yes, the UC3854N-F integrates a 1 A peak totem-pole gate driver (Pin 16) capable of directly driving power MOSFET gates. It delivers 12.8 V high-level output at –200 mA load and has 35 ns rise/fall times with 1 nF load. Designers must use ≥5 Ω series gate resistance to prevent overshoot - a requirement explicitly stated in the UC3854N-F datasheet for reliable operation.
How does the UC3854N-F implement soft-start, and what component sets its duration?
The UC3854N-F implements soft-start via the SS pin (Pin 13), which is internally sourced with –14 µA. An external capacitor from SS to GND sets the ramp time: t ≈ 0.54 × C (in µF) seconds to reach 7.5 V. For example, a 2.2 µF capacitor yields ~1.2 s soft-start. This linear ramp controls the voltage amplifier reference, gradually increasing PWM duty cycle - a feature confirmed in the UC3854N-F Applications Information section.
UC3854N-F Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Mode:
- Average Current
- Frequency - Switching:
- 200kHz
- Current - Startup:
- 1.5 mA
- Voltage - Supply:
- 14.5V ~ 30V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
UC3854N-F FAQ
1.How can I place an order for UC3854N-F through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3854N-F 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 UC3854N-F reliable?
The price and inventory of UC3854N-F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3854N-F is usually 5 days.
3.What payment methods are accepted for UC3854N-F?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3854N-F transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3854N-F?
UC3854N-F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3854N-F 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 UC3854N-F?
For technical support, including UC3854N-F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3854N-F requirements.
6.How does Aetrix verify that UC3854N-F is sourced from the original manufacturer or authorized distributors?
All UC3854N-F 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 UC3854N-F meets industry standards.
7.What is the process for return or replacement of UC3854N-F?
All UC3854N-F units undergo pre-shipment inspection (PSI). If there is an issue with UC3854N-F, 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 UC3854N-F part is unused and in its original packaging.
Return procedure for UC3854N-F:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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