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Texas Instruments UC3853NG4
- Part No.:
- UC3853NG4
- Manufacturer:
- Texas Instruments
- Category:
- PFC (Power Factor Correction)
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
UC3853NG4.pdf
- Description:
- IC PFC CTR AVER CURR 94KHZ 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,600
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Product details
Overview
UC3853NG4 from Texas Instruments is an 8-pin active power factor correction (PFC) controller IC designed for average current mode control in AC-DC preregulators. It integrates a precision multiplier/squarer/divider, dual error amplifiers (voltage and current loops), internal 75 kHz oscillator with synchronization capability, RMS line voltage compensation, and a clamped high-current gate driver. It operates across 0°C to +70°C and supports universal input (85–265 VAC) in compact DIP-8 packaging.
For engineers reviewing the UC3853NG4 datasheet, UC3853NG4 pinout, UC3853NG4 application, or UC3853NG4 equivalent, this device is selected for cost-sensitive, high-efficiency PFC stages in offline SMPS where low external component count, stable loop gain over line variation, and integrated OVP protection are critical design requirements.
Technical Context
The UC3853NG4 implements average current mode PWM control using a transconductance voltage amplifier (VCOMP) and a current-sense amplifier (ICOMP) referenced to IMO - a shared node for multiplier output and current-loop inverting input. Its multiplier section accepts IAC current proportional to rectified line voltage and scales it by VCC² to achieve RMS line voltage compensation.
Internal oscillator frequency is nominally 75 kHz (56–94 kHz over line/load/temperature), synchronized via FB pin using a 2 V falling-edge clock signal. Undervoltage lockout activates below 11.5 V with 1.5–2.1 V hysteresis, and overvoltage protection triggers when FB exceeds EA reference by 90–150 mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 75 kHz typical; enables fixed-frequency continuous conduction mode (CCM) PFC operation with ±12.5 kHz tolerance over conditions. |
| Voltage Loop Transconductance | 450 µmho typical at 0–70°C; defines small-signal gain of voltage error amplifier for stable regulation of boosted DC bus. |
| Current Loop Output Sink/Source | ±150 mA peak sink / ±80 mA peak source at ICOMP; drives external compensation network and ensures robust current-loop response. |
| Multiplier Gain Constant | –0.9 V⁻¹ typical; enables precise RMS line voltage feedforward to maintain constant power stage gain across 85–265 VAC input. |
| Gate Driver Clamp Voltage | 15 V maximum at OUT; protects external MOSFET gate oxide while allowing VCC up to 40 V without external Zener. |
| Undervoltage Lockout Threshold | 13 V turn-on with 1.8 V hysteresis; prevents erratic startup during brownout and ensures clean enable/disable sequencing. |
| OVP Threshold Accuracy | ±60 mV tolerance on 90–150 mV trip point above EA reference; provides fast, repeatable shutdown during output overvoltage events. |
Pinout & Package
UC3853NG4 is housed in an 8-pin plastic dual in-line package (PDIP-8), with lead finish NIPDAU and no MSL rating due to through-hole construction. Pin 1 is located at the left end of the top row when viewed from top with notch or dot orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB | Voltage amplifier inverting input / OVP comparator input / sync input | Accepts feedback from output divider (regulated to 3 V); trips OVP if >3.15 V; accepts 2 V sync pulse on falling edge. |
| GND | Power and signal reference ground | Reference for all voltages; requires low-inductance 0.1 µF ceramic bypass capacitor placement adjacent to pin. |
| IAC | AC waveform sensing input | Low-impedance node (nominally 2 V) accepting current proportional to rectified line voltage for feedforward. |
| IMO | Multiplier output / current sense inverting input | Summing node for multiplier current and sensed inductor current; must be kept ≥ –0.5 V to avoid diode conduction. |
| OUT | High-current MOSFET gate driver output | Delivers up to 500 mA peak drive with 15 V clamp; requires ≥5 Ω series gate resistor to limit overshoot. |
| ICOMP | Current loop error amplifier output | Class-A transconductance output capable of swinging above oscillator peak voltage to enable zero-duty-cycle operation. |
| VCC | Supply input / RMS voltage feedforward source | Supplies chip (12–40 V range); also feeds squarer circuit - connection to DC voltage proportional to VRMS enables gain stabilization. |
| VCOMP | Voltage loop error amplifier output | Transconductance output; compensation impedance must connect to GND (not FB) to preserve OVP functionality. |
Key Features
| Feature | Design Value |
|---|---|
| Average current mode PWM control | Enables stable, low-distortion input current shaping across universal AC input without slope compensation. |
| RMS line voltage compensation | Maintains constant loop gain via VCC²-dependent multiplier scaling, reducing THD across 85–265 VAC input range. |
| Integrated 75 kHz synchronizable oscillator | Allows phase alignment with downstream converters via FB pin, minimizing system-level EMI and beat frequencies. |
| Clamped 15 V gate driver | Eliminates need for external gate-clamp Zener, simplifying layout and improving reliability in high-VCC applications. |
| Overvoltage protection comparator | Dedicated FB-referenced comparator with 80 mV hysteresis shuts down OUT within microseconds upon output overvoltage. |
Applications
| LED Driver Power Supply | Industrial AC-DC Adapter |
|---|---|
|
Use Scenario: 100 W isolated LED driver operating from 85–265 VAC with Class B conducted EMI compliance. IC Role / Device Role / Timing Role: UC3853NG4 serves as the front-end active PFC controller, enforcing sinusoidal input current aligned with line voltage. Use Value: Achieves >0.98 power factor and <10% THD at full load, meeting IEC 61000-3-2 requirements without additional filtering. |
Use Scenario: 200 W industrial control power supply requiring stable 400 V DC bus and robust line transient response. IC Role / Device Role / Timing Role: UC3853NG4 regulates boost converter output while compensating for RMS line variations in real time. Use Value: Maintains ±1% output voltage regulation across 90–270 VAC input and 10–100% load, enabling reliable downstream DC-DC operation. |
| PC Power Supply (ATX) | Medical Equipment Power Module |
|
Use Scenario: Entry-level ATX PSU with single-stage PFC architecture targeting 80 PLUS White efficiency certification. IC Role / Device Role / Timing Role: UC3853NG4 implements CCM boost PFC with fixed 75 kHz switching, driving a 600 V MOSFET. Use Value: Reduces input filter size by 30% versus passive PFC solutions while achieving >90% efficiency at 50% load. |
Use Scenario: UL 60601-1 compliant 150 W medical power module requiring reinforced isolation and low leakage current. IC Role / Device Role / Timing Role: UC3853NG4 controls boost stage with undervoltage lockout and OVP to meet safety fault-response timing requirements. Use Value: Enables <10 ms OVP shutdown and clean UVLO restart, satisfying clause 15.3.2 fault condition recovery mandates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar active PFC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC2853N | Wider temperature range (–25°C to +85°C); identical pinout, architecture, and electrical specs except for temp grade. | Preferred for industrial environments with extended ambient; not rated for 0°C minimum cold start like UC3853NG4. | Select UC2853N when operating below 0°C is not required and higher temp margin is needed. |
| L6562A | Fixed-frequency average current mode PFC controller with similar 8-pin SOIC/DIP options; includes built-in zero-current detection for transition-mode compatibility. | Supports both CCM and DCM/CRM operation; lacks internal oscillator synchronization input and has different multiplier topology. | Choose L6562A when flexibility across conduction modes or lower standby power is prioritized over strict UC3853NG4 footprint compatibility. |
Compared with UC2853N and L6562A, the UC3853NG4 offers optimized cost and simplicity for fixed-frequency CCM PFC in commercial-grade equipment, trading extended temperature range and multi-mode flexibility for minimal external components and proven RMS compensation accuracy.
Availability
UC3853NG4 is available at Aetrix Electronics and suitable for LED driver power supplies, industrial AC-DC adapters, and PC ATX power supplies requiring stable component supply with legacy design continuity and long-term manufacturability support.
Supply support for UC3853NG4 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.
The UC3853NG4 belongs to TI's legacy UCx853 family of active PFC controllers, engineered specifically for cost-effective, high-power-factor AC-DC conversion in commercial-grade offline power supplies.
FAQ
What is the operating temperature range of the UC3853NG4?
The UC3853NG4 is specified for operation from 0°C to +70°C ambient temperature. This commercial-grade rating distinguishes it from the UC2853N (–25°C to +85°C) and UC1853 (–55°C to +125°C). The UC3853NG4's thermal performance is validated under these conditions with VCC = 16 V and standard test loads, and its internal protection circuits - including undervoltage lockout and overvoltage comparator - function reliably across this full range. Designers should ensure PCB layout provides adequate airflow or heatsinking if operating near upper limits.
How does the UC3853NG4 achieve RMS line voltage compensation?
The UC3853NG4 achieves RMS line voltage compensation by feeding the rectified and scaled AC line voltage into the VCC pin, which serves a dual role: powering the IC and providing the VCC² term to the internal multiplier/squarer/divider circuit. This architecture causes the multiplier gain to scale inversely with input voltage squared, maintaining constant loop gain and minimizing input current distortion across 85–265 VAC. The UC3853NG4's multiplier gain constant is –0.9 V⁻¹ typical, and its transconductance voltage amplifier (VCOMP) is designed to interface directly with this compensated signal path without external scaling.
Can the UC3853NG4 be synchronized to an external clock?
Yes, the UC3853NG4 supports external synchronization via its FB pin, which doubles as a sync input. A 2 V falling-edge clock signal with 100 V/µs slew rate can be injected through a coupling capacitor to align the internal 75 kHz oscillator with downstream converters. This capability is explicitly documented in the Electrical Characteristics table under "Synchronization Pulse Amplitude" and "Synchronization Frequency Range (100 kHz)". Synchronization reduces beat frequencies and improves EMI performance in multi-converter systems - a key advantage over non-synchronizable PFC controllers.
What is the purpose of the IMO pin on the UC3853NG4?
The IMO pin on the UC3853NG4 serves as both the output of the internal precision multiplier and the inverting input of the current loop error amplifier. This dual-function node enables differential current sensing by summing multiplier output current (proportional to VRMS × Iref) with sensed inductor current, rejecting ground noise and simplifying compensation. Designers must keep IMO ≥ –0.5 V to prevent conduction of the internal protection diode, and use a 3.9 kΩ input resistance to minimize bias-current-induced offset. This architecture is central to the UC3853NG4's average current mode control implementation.
Does the UC3853NG4 include overvoltage protection, and how does it work?
Yes, the UC3853NG4 includes a dedicated overvoltage protection (OVP) comparator referenced to the FB pin. It triggers when the FB voltage exceeds the voltage amplifier's reference by 90–150 mV - corresponding to ~3.15 V for a nominal 3 V regulation point - and immediately disables the OUT driver. The comparator features 80 mV hysteresis to prevent chatter during recovery. Unlike many controllers that rely on external circuitry, this OVP is fully integrated, requires no external components, and responds within microseconds. Its behavior is verified across temperature and supply conditions per the Absolute Maximum Ratings and Electrical Characteristics tables.
UC3853NG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Mode:
- Average Current
- Frequency - Switching:
- 56kHz ~ 94kHz
- Current - Startup:
- 250 µA
- Voltage - Supply:
- 12V ~ 40V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
UC3853NG4 FAQ
1.How can I place an order for UC3853NG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3853NG4 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 UC3853NG4 reliable?
The price and inventory of UC3853NG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3853NG4 is usually 5 days.
3.What payment methods are accepted for UC3853NG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3853NG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3853NG4?
UC3853NG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3853NG4 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 UC3853NG4?
For technical support, including UC3853NG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3853NG4 requirements.
6.How does Aetrix verify that UC3853NG4 is sourced from the original manufacturer or authorized distributors?
All UC3853NG4 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 UC3853NG4 meets industry standards.
7.What is the process for return or replacement of UC3853NG4?
All UC3853NG4 units undergo pre-shipment inspection (PSI). If there is an issue with UC3853NG4, 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 UC3853NG4 part is unused and in its original packaging.
Return procedure for UC3853NG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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