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Texas Instruments LM5181NGUR
- Part No.:
- LM5181NGUR
- Manufacturer:
- Texas Instruments
- Package:
- 8-WDFN Exposed Pad
- Datasheet:
-
LM5181NGUR.pdf
- Description:
- IC REG FLYBACK 5V 500MA 8WSON
- Quantity:
- Payment:
- Shipping:
Inventory:7,283
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Product details
Overview
LM5181NGUR from Texas Instruments is a primary-side regulated (PSR) flyback DC/DC controller IC with integrated 100-V, 0.75-A N-channel MOSFET, supporting 4.5 V to 65 V input and delivering up to 4 W isolated output power. It achieves ±1.5% total output regulation accuracy, operates in boundary conduction mode (BCM), and eliminates optocoupler or auxiliary winding requirements for feedback. Used in IGBT gate drive supplies and isolated field transmitters.
For engineers reviewing the LM5181NGUR datasheet, LM5181NGUR pinout, LM5181NGUR application, or LM5181NGUR equivalent, key selection considerations include its 8-pin WSON package with wettable flanks, programmable soft start, temperature-compensated feedback, hiccup-mode overcurrent protection, and functional safety documentation support.
Technical Context
The LM5181NGUR implements variable-frequency peak current-mode (VFPCM) control with three operating modes: BCM at heavy loads, DCM at medium loads (clamped at 350 kHz max), and frequency foldback mode (FFM) at light loads (down to 12 kHz). Its PSR architecture samples reflected flyback voltage at secondary zero-current crossing to regulate output without isolation barrier components.
Internal integration includes a trimmed 1.21-V reference tied to RSET, type-2 compensation network, precision enable comparator with 1.45 V rising threshold and 50 mV hysteresis, and thermal shutdown at 175°C with 6°C hysteresis. The 0.4-Ω MOSFET on-resistance and 140 ns minimum on-time support high-efficiency operation across wide line and load ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 65 V; supports industrial 24 V/48 V rails and transient ride-through down to 3.5 V after startup |
| Integrated MOSFET | 100-V, 0.75-A N-channel; enables compact 4-W isolated supply without external switch |
| Output Regulation Accuracy | ±1.5% total; achieved via PSR sampling and optional TC pin compensation for diode VF drift |
| Switching Frequency Range | 12 kHz to 350 kHz; dynamically adjusts across BCM/DCM/FFM modes for optimal efficiency |
| Soft Start | 6-ms internal or externally programmable via SS/BIAS capacitor; controls inrush and stabilizes startup |
| Operating Junction Temp | –40°C to +150°C; qualified for harsh environments including motor drives and HVAC systems |
| Protection Features | Hiccup-mode OCP, thermal shutdown with auto-recovery, input UVLO with hysteresis, and shutdown IQ = 3 µA |
Pinout & Package
The LM5181NGUR is housed in an 8-pin, 4.00 mm × 4.00 mm thermally enhanced WSON package with wettable flanks (NGU suffix), optimized for PCB thermal relief and automated optical inspection.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW | Switch node | Drain of internal 100-V MOSFET; connects directly to primary winding of flyback transformer |
| FB | Primary-side feedback input | Senses reflected flyback voltage; ratio of FB-to-SW resistor and RSET sets output voltage |
| VIN | Power input | Supplies internal bias regulators and enables input voltage sensing; requires low-impedance path |
| EN/UVLO | Enable and UVLO programming | Three-state control: <1.1 V = shutdown, 1.1–1.5 V = standby, >1.5 V = active; supports precision UVLO via resistor divider |
| SS/BIAS | Soft start or external bias input | Connect capacitor for programmable soft start; >5.5 V enables external bias for reduced IQ and higher efficiency |
| TC | Temperature compensation | Adjusts feedback setpoint to counteract thermal drift of flyback diode forward voltage |
| RSET | Reference current setting | 12.1-kΩ to GND sets 100-µA reference current and 1.21-V internal reference voltage |
| GND | Analog and power ground | Common return for control circuitry and MOSFET source; die attach pad must connect to PCB ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation (PSR) | Eliminates optocoupler, TL431, and transformer auxiliary winding - reduces BOM count and improves reliability |
| Quasi-resonant switching in BCM | Reduces EMI and diode reverse recovery losses; enables CISPR 32 compliance without complex filtering |
| Functional safety documentation | Available FIT data, FMEA reports, and safety analysis templates for ISO 26262 and IEC 61508 system design |
| Robust protection suite | Hiccup-mode OCP prevents thermal runaway during sustained overload; thermal shutdown recovers automatically after cooldown |
| Ultra-low quiescent current | 25–40 µA active IQ with external bias; 3 µA shutdown IQ extends battery-backed or energy-harvesting runtime |
Applications
| Isolated Field Transmitters | Motor Drive Gate Supplies |
|---|---|
Use Scenario: 4–20 mA loop-powered sensor in hazardous industrial zones requiring galvanic isolation and wide input range. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller providing stable 5 V or 12 V isolated bias for signal conditioning and ADC. Use Value: ±1.5% regulation ensures precise analog measurement; 65-V max input handles 48 V DC distribution surges. | Use Scenario: Isolated gate driver supply for IGBTs or SiC MOSFETs in variable-frequency drives and servo amplifiers. IC Role / Device Role / Timing Role: Compact 4-W PSR flyback generating dual-rail gate voltage (e.g., +15 V/–5 V) from single 24 V bus. Use Value: Integrated 100-V MOSFET withstands IGBT switching transients; BCM operation minimizes EMI near sensitive control circuitry. |
| Building Automation HVAC | Multi-output Analog Input Modules |
Use Scenario: Centralized HVAC controller powering isolated sensors, valves, and communication interfaces across large facilities. IC Role / Device Role / Timing Role: Single-chip isolated DC/DC converter delivering 5 V for microcontroller and 3.3 V for RS-485 transceivers. Use Value: –40°C to +150°C junction rating supports operation inside hot equipment cabinets; low EMI simplifies EMC certification. | Use Scenario: PLC analog input module requiring multiple isolated rails (±15 V, +5 V, +3.3 V) for precision op-amps and ADCs. IC Role / Device Role / Timing Role: PSR flyback with multi-winding transformer generating independent isolated outputs from one controller. Use Value: No optocouplers reduce component aging risk; ±1.5% regulation maintains 16-bit ADC accuracy across temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar PSR flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28911DR | 65-V input, integrated 700-V MOSFET, fixed 50-kHz frequency, no TC pin or programmable soft start | Better suited for universal AC input (85–265 VAC); lacks temperature compensation and fine-tuned startup control | Select UCC28911DR when AC/DC front-end integration is required and thermal drift compensation is not critical. |
| LM5021MMX/NOPB | External MOSFET required, 100-V input, current-mode PWM, no PSR capability - needs optocoupler feedback | Supports higher power (>10 W) and custom transformer designs but increases solution size and component count | Choose LM5021MMX/NOPB when output power exceeds 4 W or when secondary-side regulation with tighter tolerance is mandatory. |
Compared with UCC28911DR and LM5021MMX/NOPB, the LM5181NGUR uniquely delivers PSR-based isolation with integrated 100-V/0.75-A MOSFET, temperature-compensated feedback, and functional safety documentation - making it optimal for compact, reliable, and certified 4-W industrial DC/DC supplies.
Availability
LM5181NGUR is available at Aetrix Electronics and suitable for isolated field transmitters, motor drive gate supplies, and building automation HVAC systems requiring stable component supply, long-term lifecycle support, and automotive-grade reliability validation.
Supply support for LM5181NGUR 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 industrial and automotive qualification expertise.
The LM5181NGUR belongs to TI's high-voltage DC/DC controller product line, engineered specifically for compact, isolated, and robust power conversion in factory automation, motor control, and process instrumentation.
FAQ
What is the maximum output power achievable with the LM5181NGUR?
The LM5181NGUR delivers up to 4 W of isolated output power using its integrated 100-V, 0.75-A MOSFET. This limit is determined by thermal constraints and peak current capability under typical BCM operation. Higher power is possible only with external MOSFETs or parallel configurations - neither supported by the LM5181NGUR's internal architecture. Designers must verify transformer selection and layout thermal performance per TI's SNVSBM6A datasheet Section 9.
Does the LM5181NGUR require an optocoupler for output voltage regulation?
No, the LM5181NGUR does not require an optocoupler. It uses primary-side regulation (PSR) by sampling the reflected flyback voltage at the SW pin during secondary zero-current detection. This eliminates the need for optocouplers, TL431 references, or auxiliary transformer windings - reducing component count, cost, and long-term reliability risks. The LM5181NGUR achieves ±1.5% regulation accuracy solely through this PSR method.
How is output voltage set on the LM5181NGUR?
Output voltage on the LM5181NGUR is set by two resistors: a feedback resistor (RFB) from FB to SW, and RSET (12.1 kΩ) from RSET to GND. The ratio RFB/RSET determines the output based on the internal 1.21-V reference. For example, a 5-V output uses RFB = 158 kΩ. An optional TC pin resistor further compensates for temperature-induced diode VF drift, improving regulation stability across –40°C to +150°C.
What protection features are built into the LM5181NGUR?
The LM5181NGUR integrates hiccup-mode overcurrent protection, thermal shutdown at 175°C with 6°C hysteresis, input UVLO with adjustable hysteresis (1.45 V rising threshold), and low-quiescent-current shutdown (3 µA). During overload, it enters hiccup mode - cycling on/off until fault clears - preventing thermal damage. All protections are fully internal and require no external components, ensuring robust operation in unattended industrial environments.
Can the LM5181NGUR support multiple isolated outputs?
Yes, the LM5181NGUR supports multiple isolated outputs using a multi-winding transformer. Each secondary winding requires its own rectifier and filter, with regulation maintained on the primary side via reflected voltage sampling from the main output winding. Cross-regulation between secondaries depends on winding coupling and loading balance; TI recommends tight coupling and matched turns ratios. The LM5181NGUR's PSR architecture inherently supports this configuration without added feedback components.
LM5181NGUR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-WDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Flyback
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 65V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 500mA
- Frequency - Switching:
- 12kHz ~ 350kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-WSON (4x4)
LM5181NGUR FAQ
1.How can I place an order for LM5181NGUR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5181NGUR 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 LM5181NGUR reliable?
The price and inventory of LM5181NGUR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5181NGUR is usually 5 days.
3.What payment methods are accepted for LM5181NGUR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5181NGUR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM5181NGUR?
LM5181NGUR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5181NGUR 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 LM5181NGUR?
For technical support, including LM5181NGUR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5181NGUR requirements.
6.How does Aetrix verify that LM5181NGUR is sourced from the original manufacturer or authorized distributors?
All LM5181NGUR 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 LM5181NGUR meets industry standards.
7.What is the process for return or replacement of LM5181NGUR?
All LM5181NGUR units undergo pre-shipment inspection (PSI). If there is an issue with LM5181NGUR, 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 LM5181NGUR part is unused and in its original packaging.
Return procedure for LM5181NGUR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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