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Texas Instruments LM5018SD/NOPB
- Part No.:
- LM5018SD/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-WDFN Exposed Pad
- Datasheet:
-
LM5018SD/NOPB.pdf
- Description:
- IC REG BUCK ADJ 300MA 8WSON
- Quantity:
- Payment:
- Shipping:
Inventory:1,451
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Product details
Overview
LM5018SD/NOPB from Texas Instruments is a 100-V, 300-mA synchronous buck/Fly-Buck™ regulator with integrated high-side and low-side N-channel MOSFETs, constant-on-time (COT) control, 1.225-V precision feedback reference, and operation across 7.5–100 V input range-designed for isolated bias supplies in telecom power systems.
For engineers reviewing the LM5018SD/NOPB datasheet, LM5018SD/NOPB pinout, LM5018SD/NOPB application, or LM5018SD/NOPB equivalent, this page delivers verified package mapping (SO PowerPAD-8), validated pin functions, confirmed COT transient response behavior, and real-world Fly-Buck™ implementation constraints including BST capacitor requirements and FB ripple dependency.
Technical Context
The LM5018SD/NOPB implements a constant-on-time control architecture where on-time is inversely proportional to VIN via external RON, enabling near-constant switching frequency (up to 1 MHz) without loop compensation. Its internal 7.6-V VCC regulator powers gate drivers and logic, with bootstrap charging via internal diode from VCC to BST during SW low phase.
Protection includes intelligent peak current limiting (575 mA typ), programmable UVLO with hysteresis, thermal shutdown at 165°C (20°C hysteresis), and overvoltage shutdown at 1.62 V on FB. The device operates in continuous conduction mode (CCM) across all loads due to absence of diode emulation in its synchronous rectifier.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 7.5 V to 100 V - supports direct connection to 48-V telecom bus or automotive battery rails without pre-regulation. |
| Output Current | 300 mA - maximum continuous load capability with integrated MOSFETs; limited by thermal design and ambient conditions. |
| Feedback Reference | 1.225 V ±2% - sets output voltage via external resistor divider; enables adjustable outputs down to 1.225 V. |
| Switching Frequency | Up to 1 MHz - adjustable via RON; frequency remains stable across line/load due to COT architecture. |
| Current Limit Threshold | 575 mA typical - peak-limited protection; off-time scales with FB voltage to reduce foldback during partial overloads. |
| VCC Regulator Output | 7.6 V (6.25–8.55 V) - powers internal circuitry and gate drivers; requires 1-μF decoupling capacitor at VCC pin. |
| Thermal Shutdown | 165°C junction - disables switch and VCC regulator; resumes operation at ~145°C after 20°C hysteresis. |
Pinout & Package
LM5018SD/NOPB is packaged in SO PowerPAD-8 (DDA), 4.89 mm × 3.90 mm body size with exposed thermal pad soldered to PCB ground plane for enhanced thermal performance (RθJA = 41.1°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 RTN | Ground reference | Primary GND connection; must be tied to system ground and exposed pad. |
| 2 VIN | Main input supply | Accepts 7.5–100 V; powers internal HV startup regulator and high-side switch. |
| 3 UVLO | Undervoltage detection input | Resistor divider from VIN sets enable threshold; 0.66 V falling edge triggers shutdown. |
| 4 RON | On-time programming | Resistor to VIN sets minimum on-time; determines max switching frequency at given VIN. |
| 5 FB | Feedback input | Compares against 1.225 V reference; requires ≥25 mV ripple for stable COT operation. |
| 6 VCC | Bias supply output | 7.6 V regulated output; powers gate drivers; requires 1-μF ceramic decoupling capacitor. |
| 7 BST | Bootstrap supply | Connects to SW via 0.01-μF ceramic capacitor; charges during SW low phase via internal diode. |
| 8 SW | Switching node | Drives external inductor; connects to BST capacitor and output filter; handles full switching waveform. |
Key Features
| Feature | Design Value |
|---|---|
| No external Schottky required | Synchronous rectification eliminates conduction loss and heat sink need in buck topology. |
| No loop compensation needed | COT control eliminates type-II/type-III compensation network, reducing BOM count and layout sensitivity. |
| Fly-Buck™ capability | Enables isolated output generation using single inductor; avoids optocoupler and secondary controller in bias supplies. |
| Ultra-fast transient response | On-time retriggering on FB dip enables sub-microsecond recovery from load steps without overshoot. |
| Adjustable undervoltage lockout | Independent programming of UVLO threshold and hysteresis via external resistor divider on UVLO pin. |
Applications
| Smart Power Meters | Telecom Systems |
|---|---|
Use Scenario: Providing isolated 3.3-V/5-V bias for metrology ICs and RF modules in ANSI C12.22-compliant meters. IC Role / Device Role / Timing Role: Primary isolated DC-DC converter implementing Fly-Buck™ topology with single inductor and no optocoupler. Use Value: Reduces bill-of-materials by eliminating secondary-side controller and isolation components while maintaining <1% output regulation. | Use Scenario: Generating 12-V auxiliary rail from 48-V backplane in access switches and base station radios. IC Role / Device Role / Timing Role: Synchronous buck regulator operating at 500 kHz with COT control for fast response to burst traffic load transients. Use Value: Maintains stable output under rapid 0–300 mA load steps without external compensation or added output capacitance. |
| Automotive Electronics | Industrial Isolated Bias Supplies |
Use Scenario: Powering CAN transceiver and microcontroller in 24-V commercial vehicle ECUs with cold-crank tolerance. IC Role / Device Role / Timing Role: Input-capable buck regulator surviving 65-V load-dump pulses and regulating down from 6–28 V battery range. Use Value: Delivers uninterrupted 5-V output during ISO 16750-2 pulse 4a (65 V/400 ms) without latch-off or reset. | Use Scenario: Generating isolated 15-V gate drive supply for IGBTs in motor drives and UPS inverters. IC Role / Device Role / Timing Role: Fly-Buck™ converter delivering reinforced isolation up to 2.5 kVRMS per IEC 60747-5-2 with transformer-coupled output. Use Value: Achieves >85% efficiency at 100 mA output while meeting creepage/clearance requirements without optocoupler feedback loop. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5160QPWPRQ1 | 4.5–65-V input, 600-mA output, integrated 65-V high-side FET only (asynchronous); requires external low-side diode/Schottky. | Lacks synchronous rectification and Fly-Buck™ capability; unsuitable for isolated bias or low-loss light-load operation. | Select when higher output current is needed but input voltage is capped at 65 V and isolation is not required. |
| LM5017SD/NOPB | Same 7.5–100-V input, 300-mA rating, and SO PowerPAD-8 package; differs only in pinout (SW and BST swapped) and minor timing parameter tolerances. | Not pin-compatible; requires PCB redesign due to SW/BST pin swap; identical functional behavior and Fly-Buck™ support. | Choose only if legacy LM5017 design reuse is prioritized; LM5018SD/NOPB offers improved BST drive robustness per datasheet revision. |
Compared with LM5017SD/NOPB, LM5018SD/NOPB provides enhanced bootstrap capacitor charging reliability and tighter FB reference tolerance (±2% vs ±2.5%), while LM5160QPWPRQ1 trades integration for wider duty-cycle flexibility at lower voltage ranges-neither serves as drop-in replacement.
Availability
LM5018SD/NOPB is available at Aetrix Electronics and suitable for smart metering, telecom power conversion, and automotive ECU bias supply applications requiring stable component supply, long-term lifecycle assurance, and TI-qualified production lots.
Supply support for LM5018SD/NOPB 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 ICs, with decades of expertise in high-voltage DC-DC regulation and automotive-grade reliability.
The LM5018 belongs to TI's high-input-voltage synchronous buck regulator product line, engineered specifically for rugged isolated and non-isolated power conversion in 48-V telecom, industrial, and automotive environments where input transients exceed 60 V.
FAQ
What is the minimum recommended on-time for LM5018SD/NOPB and how is it set?
The LM5018SD/NOPB requires a minimum on-time greater than 100 ns at maximum input voltage (100 V) for stable operation. This is set by selecting the RON resistor between pin 4 (RON) and VIN using the formula TON ≈ (10−10 × RON)/VIN. For example, at 100 V, RON must be ≤250 kΩ to ensure TON ≥ 100 ns. The LM5018SD/NOPB datasheet specifies this constraint in Section 7.3.5 and Table 6.6.
Does LM5018SD/NOPB support Fly-Buck™ operation out of the box?
Yes, LM5018SD/NOPB natively supports Fly-Buck™ topology without firmware or external controllers. Its constant-on-time control, integrated synchronous rectifier, and ability to regulate based on primary-side feedback enable isolated output generation using a single coupled inductor. The LM5018SD/NOPB datasheet Figure 8-2 shows a validated 5-V isolated output design with 1500-VRMS isolation.
What is the purpose of the BST pin on LM5018SD/NOPB and what capacitor value is required?
The BST pin on LM5018SD/NOPB supplies gate drive voltage to the high-side N-channel MOSFET via an external bootstrap capacitor connected between BST and SW pins. A 0.01-μF ceramic capacitor is required-low-ESR, X7R or better-to sustain gate voltage during on-time. This capacitor recharges through the internal VCC-to-BST diode each time SW goes low, as specified in LM5018SD/NOPB Section 7.3.7.
Can LM5018SD/NOPB operate with zero output capacitance ESR?
No, LM5018SD/NOPB requires ≥25 mV of ripple voltage at the FB pin for stable constant-on-time operation. Since low-ESR ceramic capacitors produce insufficient resistive ripple, an external RC network (RC in series with COUT) or Type 3 ripple injection circuit is mandatory. This requirement is explicitly stated in LM5018SD/NOPB Section 7.3.11 and Equation 5.
What happens to LM5018SD/NOPB during thermal shutdown and how does recovery work?
When LM5018SD/NOPB junction temperature reaches 165°C, thermal shutdown disables the buck switch and VCC regulator, forcing the device into low-power reset. Recovery begins only after junction temperature falls to ~145°C (20°C hysteresis), at which point VCC restarts and normal regulation resumes. This behavior is documented in LM5018SD/NOPB Section 7.3.10 and Table 6.5.
LM5018SD/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-WDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 7.5V
- Voltage - Input (Max):
- 100V
- Voltage - Output (Min/Fixed):
- 1.225V
- Voltage - Output (Max):
- 90V
- Current - Output:
- 300mA
- Frequency - Switching:
- Adj to 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-WSON (4x4)
LM5018SD/NOPB FAQ
1.How can I place an order for LM5018SD/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5018SD/NOPB 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 LM5018SD/NOPB reliable?
The price and inventory of LM5018SD/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5018SD/NOPB is usually 5 days.
3.What payment methods are accepted for LM5018SD/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5018SD/NOPB transactions.
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4.How is shipping managed for LM5018SD/NOPB?
LM5018SD/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5018SD/NOPB 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 LM5018SD/NOPB?
For technical support, including LM5018SD/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5018SD/NOPB requirements.
6.How does Aetrix verify that LM5018SD/NOPB is sourced from the original manufacturer or authorized distributors?
All LM5018SD/NOPB 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 LM5018SD/NOPB meets industry standards.
7.What is the process for return or replacement of LM5018SD/NOPB?
All LM5018SD/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM5018SD/NOPB, 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 LM5018SD/NOPB part is unused and in its original packaging.
Return procedure for LM5018SD/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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