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Texas Instruments UC3854NG4
- Part No.:
- UC3854NG4
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
UC3854NG4.pdf
- Description:
- IC PFC CTR AV CURR 200KHZ 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,112
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Product details
Overview
UC3854NG4 from Texas Instruments is a high-power-factor preregulator IC implementing average current-mode control for boost-type active PFC stages. It integrates a 7.5-V precision reference, analog multiplier/divider, voltage and current amplifiers, fixed-frequency PWM, and 1-A totem-pole gate driver - enabling >0.99 power factor and <5% line-current distortion in offline AC/DC supplies operating from 75–275 VAC at 50–400 Hz.
For engineers reviewing the UC3854NG4 datasheet, UC3854NG4 pinout, UC3854NG4 application, or UC3854NG4 equivalent, key selection considerations include its 55 kHz typical oscillator frequency (RSET = 15 kΩ), –4 mV to +4 mV current amplifier offset, 70–100 dB voltage amplifier gain, 0–70°C operating junction temperature range, and SOIC-16 package compatibility with universal-input industrial and telecom power supplies.
Technical Context
The UC3854NG4 employs average current-mode control - not peak current-mode - eliminating slope compensation requirements while maintaining sinusoidal line current under continuous/discontinuous conduction transitions. Its analog multiplier accepts IAC (6-V biased current input) and VRMS (1.5–3.5 V feedforward) to generate a shaped reference for the current amplifier.
Control loop architecture includes a voltage error amplifier (VAOUT output, 0.5–5.8 V swing) feeding the multiplier, whose output (MULTOUT) drives a wideband current amplifier (1-MHz bandwidth, 80–110 dB gain) that compares sensed line current (via ISENSE/MULTOUT differential pair) against the multiplier output to regulate GTDRV duty cycle. The 1-A gate driver features internal 15-V clamp and 35-ns rise/fall times.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator frequency | 55 kHz typical (RSET = 15 kΩ); sets fixed PWM switching frequency for EMI-controlled boost operation. |
| Voltage reference (VREF) | 7.5 V ±0.15 V over temperature; powers external circuitry and serves as soft-start and error amplifier reference. |
| Current amplifier offset | ±4 mV max; ensures accurate zero-crossing detection and low THD in line-current shaping. |
| Voltage amplifier gain | 70–100 dB; provides high-loop gain for tight DC output voltage regulation (e.g., 400 VDC). |
| Gate driver output | 1-A peak, 12.8 V min at –200 mA load; directly drives MOSFET gates without external buffers in ≤250-W designs. |
| Operating junction temp | 0°C to 70°C; defines thermal derating envelope for industrial-grade reliability in enclosed power supplies. |
| Supply voltage (VCC) | 10–20 V recommended; UVLO turn-on at 16 V typical ensures stable startup after rectified AC rail reaches threshold. |
Pinout & Package
UC3854NG4 is housed in a 16-pin SOIC (DW) package measuring 7.50 mm × 10.30 mm, with GND on Pin 1 and GTDRV on Pin 16. Thermal resistance RθJA is 71.5°C/W, requiring minimal copper area for standard industrial PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1) | Power and signal reference | Return path for VCC/VREF bypass caps, CT discharge current, and all internal amplifiers; must be low-inductance connection. |
| PKLMT (2) | Peak current limit input | Threshold = 0 V; connects to negative side of current-sense resistor to enable fast overcurrent shutdown (<175 ns delay). |
| CAOUT (3) | Current amplifier output | Emitter-follower output driving PWM comparator; swings to near GND to force zero duty cycle during fault or disable. |
| ISENSE (4) | Current-sense inverting input | Differential input (with MULTOUT) for line-current sensing; operates down to –0.3 V; protected by GND clamp diodes. |
| MULTOUT (5) | Multiplier output / current-sense non-inverting input | High-impedance current output (–27 µA typical) and node shared with ISENSE+; enables noise-rejecting differential current sensing. |
| IAC (6) | AC line voltage feedforward input | 6-V biased current input (100 µA nominal); cancels RMS line variation in multiplier output to maintain constant power transfer. |
| VAOUT (7) | Voltage amplifier output | 0.5–5.8 V regulated output; feeds multiplier and remains active during ENA/VCC disable to preserve feedback capacitor charge. |
| VRMS (8) | RMS line voltage input | 1.5–3.5 V input range; provides feedforward scaling to multiplier for line-voltage-independent output regulation. |
| VREF (9) | 7.5-V precision reference output | 10-mA capable; disabled when VCC < UVLO or ENA = low; requires 0.1-µF ceramic bypass to GND for stability. |
| ENA (10) | Enable logic input | 2.55 V typical threshold; releases SS clamp and enables oscillator/VREF; not intended for high-speed PWM shutdown. |
| VSENSE (11) | Voltage feedback inverting input | Connects to resistive divider from boost output (e.g., 400 VDC); bias current < ±500 nA minimizes divider error. |
| RSET (12) | Oscillator charging & multiplier limit set | Resistor to GND programs oscillator frequency and maximum multiplier output current (IMULTOUT ≤ 3.75 V/RRSET). |
| SS (13) | Soft-start timing node | Internally sourced 14-mA current charges external capacitor; ramps VAOUT reference to prevent output overshoot at startup. |
| CT (14) | Oscillator timing capacitor | Capacitor to GND sets oscillator ramp frequency; valley = 1.1 V, peak = 5.4 V; critical for EMI and efficiency tuning. |
| VCC (15) | Positive supply input | 10–20 V operation; 16 mA typical supply current; must be bypassed with ≥0.1-µF ceramic cap directly to GND. |
| GTDRV (16) | Gate drive output | Totem-pole MOSFET driver; clamped to 15 V internally; requires ≥5 Ω series gate resistor to suppress ringing on capacitive loads. |
Key Features
| Feature | Design Value |
|---|---|
| Average current-mode control | Enables stable, low-distortion line-current shaping across CCM/DCM transitions without slope compensation. |
| Feedforward line regulation (VRMS + IAC) | Compensates for input voltage variations in real time, maintaining constant output power and <5% THD over 75–275 VAC. |
| 1-A integrated gate driver | Drives MOSFET gates directly in ≤250-W boost PFC stages, eliminating need for external drivers and reducing BOM count. |
| 7.5-V precision reference (VREF) | Stable, low-drift reference for soft-start, error amplifiers, and external circuitry - reduces system component count and calibration burden. |
| Low-noise analog multiplier/divider | Processes IAC and VRMS inputs to generate instantaneous current command, minimizing cross-over distortion and enabling 0.999 PF measured performance. |
Applications
| Industrial AC/DC Power Supplies | Telecom Rectifier Modules |
|---|---|
|
Use Scenario: 250-W universal-input (85–264 VAC) front-end for programmable logic controllers and motor drives. IC Role / Device Role / Timing Role: UC3854NG4 acts as the active PFC controller in a continuous-conduction-mode boost stage, regulating input current waveform to match sinusoidal voltage phase. Use Value: Achieves 0.999 measured power factor and 3.81% THD per EN61000-3-2 Class D, enabling compliance without external harmonic filters. |
Use Scenario: 48-V telecom rectifier with 300-W output and hold-up time requirement. IC Role / Device Role / Timing Role: UC3854NG4 controls the boost preregulator to deliver stable 400 VDC bus, feeding downstream isolated DC/DC converters. Use Value: Fixed 55 kHz switching enables predictable EMI filtering; 70°C max junction rating supports compact, fanless telecom chassis design. |
| Medical Equipment Power | Uninterruptible Power Supplies (UPS) |
|
Use Scenario: Diagnostic imaging system requiring low EMI and high reliability in hospital environments. IC Role / Device Role / Timing Role: UC3854NG4 implements feedforward-regulated PFC to minimize conducted emissions into sensitive analog signal paths. Use Value: Low-noise amplifier design and 1-MHz current amplifier bandwidth reject switching noise transients, preserving signal integrity. |
Use Scenario: Line-interactive UPS with battery backup and automatic voltage regulation. IC Role / Device Role / Timing Role: UC3854NG4 manages bidirectional energy flow during line/battery transitions via precise voltage and current loop coordination. Use Value: Soft-start (SS pin) and undervoltage lockout (16 V turn-on) ensure clean startup and graceful shutdown during brownouts or grid instability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar active power factor correction applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC3854D | Pin-compatible SOIC-16 variant with identical electrical specs; differs only in TI's newer UCC prefix and enhanced ESD rating (±3-kV HBM vs ±2.5-kV). | Same 0–70°C temp grade and functional block diagram; validated for identical 250-W PFC designs per TI application note SLUA322. | Select UCC3854D for new designs requiring extended long-term availability and marginally improved robustness in handling ESD during assembly. |
| ICE3PCS01G | Fixed-frequency CCM PFC controller with integrated 650-V MOSFET; lacks analog multiplier - uses digital line-voltage sampling and internal lookup tables. | Targets cost-sensitive consumer/IT power supplies; not suitable for high-precision industrial THD requirements due to inherent quantization noise. | Choose ICE3PCS01G only for ≤150-W applications where BOM reduction outweighs need for <4% THD; UC3854NG4 remains superior for 0.999 PF validation. |
Compared with UCC3854D, UC3854NG4 offers identical control accuracy but slightly lower ESD immunity; versus ICE3PCS01G, UC3854NG4 delivers superior THD performance and design flexibility via analog multiplier architecture, at the cost of discrete MOSFET selection and layout effort.
Availability
UC3854NG4 is available at Aetrix Electronics and suitable for industrial AC/DC power supplies, telecom rectifier modules, and medical equipment power systems requiring stable component supply, long-lifecycle support, and guaranteed traceability.
Supply support for UC3854NG4 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 leadership in power conversion ICs.
The UC3854NG4 belongs to TI's legacy UCx854 family of high-power-factor preregulators - designed specifically for universal-input, fixed-frequency boost PFC stages in industrial, telecom, and medical power systems demanding <5% THD and >0.99 PF.
FAQ
What is the operating temperature range for UC3854NG4?
The UC3854NG4 is rated for an operating junction temperature range of 0°C to 70°C, making it suitable for commercial and industrial ambient environments where forced air cooling is not required. This specification is confirmed in Section 7.3 (Recommended Operating Conditions) of the SLUS336A datasheet. The device's thermal metrics - including RθJA = 71.5°C/W for the SOIC-16 package - allow straightforward thermal design for typical 250-W PFC applications. UC3854NG4 does not support extended temperature grades like the UC1854 (–55°C to 125°C).
How does UC3854NG4 achieve power factor correction without slope compensation?
UC3854NG4 achieves high-fidelity power factor correction using average current-mode control instead of peak current-mode. This architecture inherently rejects noise and maintains sinusoidal line current across continuous and discontinuous conduction modes - eliminating the need for slope compensation. The current amplifier compares the sensed line current (via ISENSE and MULTOUT differential inputs) against the analog multiplier's output, generating a precise error signal for the PWM comparator. This method is explicitly detailed in Section 8.1 and Figure 10 of the UC3854NG4 datasheet.
What is the function of the VRMS pin on UC3854NG4?
The VRMS pin on UC3854NG4 accepts a DC voltage proportional to the RMS value of the rectified AC line (typically 1.5–3.5 V). This feedforward signal is squared internally and applied to the analog multiplier's divider input, enabling real-time compensation for input voltage variations. As a result, UC3854NG4 maintains constant output power and low THD across universal input ranges (75–275 VAC), without requiring slow outer voltage-loop correction. This behavior is specified in the Pin Functions table and Section 8.3 of the datasheet.
Can UC3854NG4 drive a MOSFET directly without an external gate driver?
Yes, UC3854NG4 integrates a 1-A totem-pole gate driver on the GTDRV pin, capable of directly driving power MOSFET gates in ≤250-W boost PFC applications. The output is internally clamped to 15 V to prevent gate overvoltage, and rise/fall times are 35 ns into 1 nF. A minimum 5 Ω series gate resistor is required to dampen ringing. This capability is verified in Section 7.5 (Electrical Characteristics) and Application Note SLUA322, confirming UC3854NG4's suitability for simplified, low-component-count PFC designs.
What is the purpose of the RSET pin on UC3854NG4?
The RSET pin on UC3854NG4 serves a dual function: it sets both the oscillator charging current (and thus PWM frequency) and the maximum multiplier output current. A resistor from RSET to GND determines oscillator frequency per fOSC ≈ 1.25/(RRSET × CCT), and also limits multiplier output current to ≤ 3.75 V / RRSET. For example, a 15-kΩ resistor yields ~55 kHz operation and ~250 µA max multiplier output. This relationship is defined in the Pin Functions section and Equation 1 of the UC3854NG4 datasheet.
UC3854NG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- 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
UC3854NG4 FAQ
1.How can I place an order for UC3854NG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3854NG4 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 UC3854NG4 reliable?
The price and inventory of UC3854NG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3854NG4 is usually 5 days.
3.What payment methods are accepted for UC3854NG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3854NG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3854NG4?
UC3854NG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3854NG4 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 UC3854NG4?
For technical support, including UC3854NG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3854NG4 requirements.
6.How does Aetrix verify that UC3854NG4 is sourced from the original manufacturer or authorized distributors?
All UC3854NG4 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 UC3854NG4 meets industry standards.
7.What is the process for return or replacement of UC3854NG4?
All UC3854NG4 units undergo pre-shipment inspection (PSI). If there is an issue with UC3854NG4, 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 UC3854NG4 part is unused and in its original packaging.
Return procedure for UC3854NG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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