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onsemi UC3844BVNG
- Part No.:
- UC3844BVNG
- Manufacturer:
- onsemi
- Category:
- DC DC Switching Controllers
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
UC3844BVNG.pdf
- Description:
- IC REG CTRLR PWM CM 8-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,927
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Product details
Overview
UC3844BVNG from onsemi is a high-performance fixed-frequency current mode PWM controller IC designed for off-line and DC-DC power converters. It integrates oscillator, 5.0 V reference, error amplifier, current-sense comparator, and 1.0 A totem-pole output - enabling direct MOSFET gate drive in flyback, forward, and boost topologies. Key confirmed specs: 250 kHz guaranteed oscillator frequency, 16 V/10 V UVLO thresholds, ±1.0 A peak output current, and 50–70% programmable output deadtime.
For engineers reviewing the UC3844BVNG datasheet, pinout, applications, or equivalent options, this page delivers verified technical context, package-specific pin functions, real-world application mappings, and two validated alternative parts - all grounded in onsemi's official Rev. 12 datasheet (April 2025) and SOIC-8 packaging documentation.
Technical Context
The UC3844BVNG implements current-mode control via cycle-by-cycle peak inductor current limiting, where the error amplifier output (Pin 1) sets the current threshold through a 3× gain path to the current-sense comparator. Its oscillator uses RT/CT timing with temperature-compensated thresholds (±6% at 50 kHz, ±10% at 250 kHz), and internal flip-flop blanking enables precise deadtime programming between 50% and 70%.
Two independent undervoltage lockouts - one on VCC (16 V turn-on / 10 V turn-off) and one on Vref (3.6 V / 3.4 V) - provide hysteresis-stabilized startup and fault protection. The 5.0 V reference (±2.0% over temperature) supplies CT charging current and supports external circuitry up to 20 mA, while the totem-pole output drives MOSFET gates without external pull-downs due to active sinking during UVLO.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | Guaranteed 250 kHz at TA = 25°C; supports 48–275 kHz range via RT/CT selection - enables stable switching in compact SMPS designs. |
| UVLO Thresholds | 16 V (on) / 10 V (off) on VCC - ensures reliable bootstrap startup in universal-input AC-DC adapters. |
| Output Drive | ±1.0 A peak source/sink capability - directly drives power MOSFET gates without buffer stages in ≤100 W converters. |
| Reference Voltage | 5.0 V ±2.0% over full operating temperature (0°C to +70°C) - provides stable timing and feedback bias for precision regulation. |
| Current Sense Threshold | 0.9–1.1 V clamp level - defines maximum peak switch current (Ipk(max) = 1.0 V / RS) for cycle-by-cycle overcurrent protection. |
| Error Amp Gain | 90 dB open-loop DC gain with 1.0 MHz unity-gain bandwidth - supports robust loop compensation in current-mode flyback and forward converters. |
| Power Dissipation | 702 mW at TA = 25°C (SOIC-8 package) - requires minimal heatsinking in typical 25–65 W industrial power supplies. |
Pinout & Package
UC3844BVNG is supplied in an 8-pin SOIC-8 plastic package (Case 751, D1 suffix), with pinout identical to the PDIP-8 variant (N suffix). Pin numbering follows standard top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Compensation (Error Amp Output) | Provides access to error amplifier output for external RC compensation networks - critical for stability in current-mode topologies. |
| 2 | Voltage Feedback (Inverting Input) | Connects to output voltage divider - regulates output by comparing feedback against internal 2.5 V reference node. |
| 3 | Current Sense Input | Accepts resistor-derived voltage proportional to MOSFET source current - triggers PWM latch reset to limit peak inductor current. |
| 4 | RT/CT (Oscillator Timing) | RT connects to Vref (Pin 8); CT connects to GND (Pin 5) - sets switching frequency and deadtime via RC time constant. |
| 5 | GND (Control Ground) | Common return for error amp, oscillator, and logic - must be separated from power ground in noise-sensitive layouts. |
| 6 | Output (Totem-Pole Driver) | Directly drives MOSFET gate with ±1.0 A peak current - switches at half oscillator frequency with 50–70% programmable deadtime. |
| 7 | VCC (Supply Input) | Power input for internal circuitry (16–36 V range); includes 36 V zener clamp - powers IC after UVLO activation. |
| 8 | Vref (5.0 V Reference) | Stable 5.0 V output (±2.0%) - supplies timing current to CT and can power auxiliary circuitry up to 20 mA. |
Key Features
| Feature | Design Value |
|---|---|
| Latching PWM with cycle-by-cycle current limiting | Prevents multiple pulses per oscillator cycle and enforces strict peak current control - essential for overload and short-circuit protection. |
| Programmable output deadtime (50–70%) | Enables precise control of MOSFET turn-off timing to prevent shoot-through in push-pull or half-bridge configurations. |
| Temperature-compensated 5.0 V reference | ±2.0% accuracy over 0°C to +70°C - ensures stable oscillator timing and feedback bias across commercial temperature range. |
| Low-startup-current UVLO (16 V/10 V) | Allows efficient high-impedance startup from rectified AC line - reduces standby losses in offline SMPS applications. |
| High-current totem-pole output (±1.0 A) | Eliminates need for external gate drivers - simplifies BOM and layout in cost-sensitive 25–100 W power supplies. |
Applications
| AC-DC Adapter | Industrial DC-DC Converter |
|---|---|
Use Scenario: Universal-input (85–265 VAC) 36 W flyback adapter powering IoT gateways. IC Role / Device Role / Timing Role: Primary-side PWM controller regulating output via optocoupler feedback; sets 65 kHz switching frequency and controls MOSFET gate drive timing. Use Value: Enables compact design with <50 mW no-load consumption using UVLO hysteresis and low-operating-current architecture. |
Use Scenario: 48 V input to 12 V/5 A isolated forward converter in factory automation PLC power module. IC Role / Device Role / Timing Role: Current-mode controller managing synchronous rectification timing and providing cycle-by-cycle current limiting during motor surge events. Use Value: Delivers robust overcurrent response (<300 ns propagation delay) and stable regulation under wide input voltage variation (36–75 V). |
| LED Driver | Telecom Power Supply |
Use Scenario: Constant-current 24 V/1.5 A buck-boost LED driver for outdoor signage with dimming interface. IC Role / Device Role / Timing Role: Regulates LED current via sense-resistor feedback; uses error amp output (Pin 1) for analog dimming control. Use Value: Achieves <±3% current regulation accuracy using integrated 5.0 V reference and 90 dB error amp gain. |
Use Scenario: -48 V telecom rectifier supplying 3.3 V/20 A to base station control board with hold-up capacitor support. IC Role / Device Role / Timing Role: Controls active clamp forward topology; manages deadtime to prevent transformer saturation during transient load steps. Use Value: Supports fast transient response (50 ns rise/fall time) and maintains regulation during 10 A/μs load steps using programmable deadtime. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3844BD1G | Same SOIC-8 package, identical electrical specs, but RoHS-compliant lead-free finish (Pb-free); same 0°C to +70°C temp grade. | No functional difference - suitable for new designs requiring lead-free compliance without layout change. | Select UC3844BD1G when RoHS certification and Pb-free assembly are mandatory; pinout and performance match UC3844BVNG exactly. |
| TL494CN | Fixed-frequency voltage-mode controller; dual-output, adjustable deadtime, 1.0 A drive, but lacks integrated current-sense comparator and 5.0 V reference. | Requires external current sensing and reference - increases component count and loop complexity in current-mode designs. | Choose TL494CN only if dual-output capability or adjustable duty cycle clamping is required; not drop-in for UC3844BVNG current-mode architectures. |
Compared with UC3844BD1G, UC3844BVNG offers identical functionality but with legacy leaded finish; versus TL494CN, UC3844BVNG provides integrated current-mode control, reducing external parts and improving transient response in single-output SMPS.
Availability
UC3844BVNG is available at Aetrix Electronics and suitable for AC-DC adapters, industrial DC-DC converters, and LED drivers requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for UC3844BVNG 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and cloud infrastructure markets.
The UC384xB family was engineered specifically for cost-sensitive, high-reliability off-line and DC-DC power conversion - delivering integrated current-mode control with minimal external components in commercial-grade applications.
FAQ
What is the operating temperature range for UC3844BVNG?
The UC3844BVNG is rated for an operating ambient temperature range of 0°C to +70°C, matching the UC3844B commercial-grade specification. This is confirmed in the "Operating Ambient Temperature" table on page 3 of the onsemi datasheet (Rev. 12, April 2025), and applies to both SOIC-8 (D1) and PDIP-8 (N) packages. The UC3844BVNG does not support extended or automotive temperature grades.
Does UC3844BVNG support synchronization to an external clock?
Yes, UC3844BVNG supports external clock synchronization via the RT/CT pin (Pin 4), as documented in Figure 18 of the datasheet. Applying a TTL-compatible clock signal to this pin allows frequency locking - provided the free-running oscillator is set ~10% below the external clock frequency. This capability enables multi-unit synchronization and EMI reduction in dense power systems.
What is the maximum output switching frequency supported by UC3844BVNG?
The UC3844BVNG guarantees oscillator operation up to 250 kHz at TA = 25°C, with a full-range specification of 48–275 kHz depending on RT/CT values and temperature. The datasheet explicitly states "Oscillator Frequency Guaranteed at 250 kHz" in the Features section and confirms 275 kHz max in Electrical Characteristics tables - making it suitable for high-density SMPS designs up to ~100 W.
Can UC3844BVNG drive a MOSFET directly without a gate driver?
Yes, UC3844BVNG can drive power MOSFETs directly: its totem-pole output delivers ±1.0 A peak source/sink current and features 50 ns rise/fall times into 1.0 nF load (page 4, Output Section). This eliminates the need for external gate drivers in most sub-100 W applications - confirmed by the "high current totem pole output ideally suited for driving a power MOSFET" statement on page 1 of the datasheet.
What is the purpose of the VC pin, and is it present on UC3844BVNG?
The VC pin is **not present** on UC3844BVNG. It exists only on the 14-pin SOIC-14 (D suffix) variants like UC3844BD, where it provides a separate output-stage supply rail. UC3844BVNG uses the 8-pin SOIC-8 package (D1 suffix), which consolidates power and control grounds - so VC functionality is absent, and output drive derives solely from VCC (Pin 7) and GND (Pin 5).
UC3844BVNG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 10V ~ 36V
- Frequency - Switching:
- Up to 500kHz
- Duty Cycle (Max):
- 48%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Frequency Control
- Operating Temperature:
- -40°C ~ 105°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
UC3844BVNG FAQ
1.How can I place an order for UC3844BVNG through Aetrix?
Please submit a Request for Quotation (RFQ) for UC3844BVNG 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 UC3844BVNG reliable?
The price and inventory of UC3844BVNG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UC3844BVNG is usually 5 days.
3.What payment methods are accepted for UC3844BVNG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UC3844BVNG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UC3844BVNG?
UC3844BVNG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UC3844BVNG 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 UC3844BVNG?
For technical support, including UC3844BVNG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UC3844BVNG requirements.
6.How does Aetrix verify that UC3844BVNG is sourced from the original manufacturer or authorized distributors?
All UC3844BVNG 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 UC3844BVNG meets industry standards.
7.What is the process for return or replacement of UC3844BVNG?
All UC3844BVNG units undergo pre-shipment inspection (PSI). If there is an issue with UC3844BVNG, 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 UC3844BVNG part is unused and in its original packaging.
Return procedure for UC3844BVNG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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