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Texas Instruments LM5008ASD/NOPB
- Part No.:
- LM5008ASD/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-WDFN Exposed Pad
- Datasheet:
-
LM5008ASD/NOPB.pdf
- Description:
- IC REG BUCK ADJ 350MA 8WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,018
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Product details
Overview
LM5008ASD/NOPB from Texas Instruments is a 95-V input, 350-mA constant-on-time (COT) synchronous buck switching regulator with integrated 100-V N-channel MOSFET, 2.5-V precision feedback reference, and internal start-up regulator. It operates from 6 V to 95 V input, delivers adjustable output down to 2.5 V, and targets high-voltage industrial power rails and automotive post-regulation.
For engineers reviewing the LM5008ASD/NOPB datasheet, LM5008ASD/NOPB pinout, LM5008ASD/NOPB application, or LM5008ASD/NOPB equivalent, key selection considerations include its no-loop-compensation COT architecture, intelligent current-limit off-timer with RCL programmability, bootstrap gate drive with pre-charge switch, thermal shutdown with 25°C hysteresis, and dual-package availability in VSSOP-8 and WSON-8.
Technical Context
The LM5008ASD/NOPB implements a constant-on-time control scheme where on-time varies inversely with VIN (TON = 1.385×10⁻¹⁰ × RT / VIN), enabling near-constant frequency across line and load variations. It operates in discontinuous conduction mode (DCM) at light loads and continuous conduction mode (CCM) at heavy loads, with automatic mode transition based on inductor current zero-crossing.
Regulation uses a 2.5-V internal reference compared against FB voltage; overvoltage protection triggers at 2.875 V. Current limiting is implemented via cycle-by-cycle detection at 0.51 A (typ), followed by an RCL- and VFB-dependent off-time generator (35 µs max at VFB = 0 V). The integrated VCC bias regulator provides 7-V gate drive with 9.2-mA current limit and bypass operation below 8.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6 V to 95 V - supports 12 V, 24 V, and 48 V telecom/automotive rails with 100-V absolute max rating. |
| Output Current | 350 mA DC - maximum continuous load capability with integrated 1.25-Ω (typ) 100-V N-MOSFET. |
| Feedback Reference | 2.5 V ±5.5 mV - precision internal reference enabling accurate output programming via RFB1/RFB2 divider. |
| Current Limit Threshold | 0.51 A (typ) at TJ = 25°C - cycle-by-cycle overcurrent protection with intelligent off-time scaling vs. VFB. |
| Thermal Shutdown | 165°C activation with 25°C hysteresis - automatic recovery at ~140°C prevents catastrophic failure during overload. |
| VCC Regulator Output | 7 V regulated (VIN > 8.5 V); tracks VIN within 100 mV (VIN < 8.5 V) - powers gate driver with 0.47-µF local decoupling. |
| Minimum On-Time | 400 ns at VIN = 95 V - sets practical upper frequency limit and ensures reliable current limit operation. |
Pinout & Package
LM5008ASD/NOPB is available in 8-pin VSSOP (DGK, 3.0 mm × 3.0 mm) and 8-pin WSON (NGU, 4.0 mm × 4.0 mm) packages, both with exposed thermal pad (WSON only). Pin functions are identical across packages.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SW | Switching node | Power switching node connecting to inductor, freewheeling diode, and bootstrap capacitor - carries high dv/dt and peak currents. |
| 2 BST | Bootstrap supply input | Input for external 0.01-µF ceramic bootstrap capacitor; charged from VCC during off-time via internal diode. |
| 3 RCL | Current limit off-time set | Resistor-to-ground sets intelligent off-time duration after current limit detection; 35 µs max when FB = 0 V. |
| 4 RTN | Ground reference | Common ground return for internal circuitry, feedback network, and external components - must be low-impedance. |
| 5 FB | Feedback input | Inverting input of regulation comparator referenced to 2.5 V; requires ≥25 mV ripple for stable COT operation. |
| 6 RT/SD | On-time set / shutdown | Resistor-to-VIN sets on-time; pulled to GND (<0.7 V) enables remote shutdown with 110-µA quiescent current. |
| 7 VCC | Bias regulator output | 7-V (regulated) or VIN-tracked (bypass) supply for gate driver; requires 0.47-µF ceramic decoupling to RTN. |
| 8 VIN | Main input supply | Primary power input (6–95 V); supplies internal bias regulator and high-side switch - rated to 100 V abs max. |
Key Features
| Feature | Design Value |
|---|---|
| No loop compensation required | Constant-on-time control eliminates external compensation network - reduces BOM count and design iteration time. |
| Intelligent current limit | Off-time scales inversely with FB voltage (35 µs at short-circuit, shorter at partial overload) - minimizes foldback and improves recovery. |
| Bootstrap pre-charge switch | 150-ns active pre-charge during minimum off-time - maintains BST-SW voltage under light-load/long-off conditions and prevents startup issues. |
| Integrated VCC bias regulator | Self-powered from VIN (6–95 V); bypasses below 8.5 V, regulates at 7 V above - eliminates need for auxiliary bias supply. |
| Thermal shutdown with auto-recovery | Shuts down at 165°C junction temperature; resumes operation at ~140°C - protects against sustained overload without manual reset. |
Applications
| Industrial Telecom Power | Automotive 48-V Post-Regulation |
|---|---|
|
Use Scenario: Non-isolated buck conversion from 48-V telecom distribution bus to 3.3-V or 5-V logic supply in base station equipment. IC Role / Device Role / Timing Role: Primary step-down regulator delivering up to 350 mA with fast transient response to handle burst-mode traffic loads. Use Value: Eliminates external loop compensation and reduces solution size versus traditional voltage-mode controllers - critical for space-constrained telecom modules. |
Use Scenario: Secondary regulation from 48-V battery rail to 12-V or 5-V subsystem supply in electric vehicle ADAS or infotainment ECUs. IC Role / Device Role / Timing Role: High-input-voltage buck converter operating in DCM at idle and CCM under load - maintains efficiency across wide duty cycle range. Use Value: Withstands 95-V transients and integrates 100-V MOSFET - avoids external HV FET and level-shifting circuitry required by lower-voltage controllers. |
| High-Voltage Industrial Sensors | Smart Grid Metering Supplies |
|
Use Scenario: Powering isolated sensor front-ends from unregulated 24-V or 36-V industrial fieldbus lines with strict EMI constraints. IC Role / Device Role / Timing Role: Constant-frequency COT regulator providing low-noise, fast-transient 3.3-V supply for precision ADCs and signal conditioners. Use Value: Ultra-fast transient response and ripple-based regulation enable stable output despite rapid load steps - essential for high-resolution sensor accuracy. |
Use Scenario: Generating auxiliary 3.3-V or 5-V supply from 120-V AC-derived DC bus in smart electricity meters with long service life requirements. IC Role / Device Role / Timing Role: Robust buck controller handling wide input variation (6–95 V) and maintaining regulation during brownouts and surges. Use Value: Integrated thermal shutdown and 125°C max junction rating ensure reliability in sealed, thermally constrained meter enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5017MH/NOPB | Higher 100-V input rating, 600-mA output, but requires external MOSFET and loop compensation - larger solution size. | Used where higher output current or adjustable frequency is needed; not drop-in due to different pinout and external FET requirement. | Select LM5017MH/NOPB only when >350 mA load or programmable frequency outweighs integration and simplicity benefits of LM5008ASD/NOPB. |
| TPS54340DDAR | Lower 42-V max input, 3.5-A output, current-mode control with full compensation - optimized for lower-voltage, higher-current apps. | Targeted at 12-V/24-V systems requiring >1 A; incompatible with 48-V+ inputs due to absolute max VIN limitation. | Choose TPS54340DDAR for cost-sensitive 24-V industrial supplies needing >1 A, but avoid for 48-V+ or space-constrained designs where LM5008ASD/NOPB's integration excels. |
Compared with LM5017MH/NOPB and TPS54340DDAR, LM5008ASD/NOPB offers the smallest footprint and lowest component count for ≤350 mA, 6–95 V buck conversion - ideal where board space, design cycle time, and transient performance are prioritized over raw current capacity or frequency flexibility.
Availability
LM5008ASD/NOPB is available at Aetrix Electronics and suitable for industrial telecom power, automotive 48-V post-regulation, and high-voltage sensor supply applications requiring stable component supply and long-term manufacturability.
Supply support for LM5008ASD/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 company specializing in analog, embedded processing, and power management ICs, with leadership in high-reliability industrial and automotive power solutions.
The LM5008A product line delivers highly integrated, easy-to-use high-voltage buck regulators targeting space-constrained applications in telecom infrastructure, automotive electrification, and industrial automation where input voltages exceed 40 V.
FAQ
What is the minimum input voltage required for stable operation of the LM5008ASD/NOPB?
The LM5008ASD/NOPB requires a minimum input voltage of 6 V for stable operation, as specified in its recommended operating conditions. Below this threshold, the internal VCC bias regulator cannot maintain sufficient gate drive voltage, and the buck switch may fail to turn on reliably. At 6 V input, the VCC regulator operates in bypass mode, tracking VIN within 100 mV - ensuring functional startup and regulation down to the rated minimum.
How does the LM5008ASD/NOPB achieve constant frequency operation despite varying input voltage?
The LM5008ASD/NOPB achieves near-constant frequency through its constant-on-time (COT) control architecture, where on-time is inversely proportional to VIN (TON = 1.385×10⁻¹⁰ × RT / VIN). As input voltage increases, on-time decreases proportionally, compensating for the higher energy per cycle and stabilizing switching frequency across the 6–95 V input range - eliminating need for loop compensation while maintaining fast transient response.
Can the LM5008ASD/NOPB be used without an external bootstrap capacitor?
No, the LM5008ASD/NOPB requires an external 0.01-µF ceramic capacitor between BST and SW pins. This bootstrap capacitor supplies gate drive voltage to the internal high-side N-MOSFET during the on-time. During off-time, it recharges from VCC via an internal diode. Omitting it causes gate drive failure, resulting in no switching action and loss of regulation - the datasheet explicitly mandates this component for proper operation.
What is the purpose of the RCL pin on the LM5008ASD/NOPB, and how does it affect current limiting?
The RCL pin on the LM5008ASD/NOPB sets the off-time duration following current limit detection. A resistor from RCL to RTN determines the forced off-time, which scales inversely with FB voltage: 35 µs maximum at VFB = 0 V (e.g., output short), decreasing at higher VFB (e.g., partial overload). This intelligent scaling minimizes foldback and accelerates recovery - unlike fixed off-time limiters, it adapts to fault severity while maintaining safe operation up to 95 V input.
Does the LM5008ASD/NOPB support remote shutdown, and what voltage level triggers it?
Yes, the LM5008ASD/NOPB supports remote shutdown via the RT/SD pin. Pulling RT/SD to ground (≤0.7 V) disables both the internal VCC regulator and the buck switch, reducing quiescent current to 110 µA (typ) at VIN = 48 V. The shutdown threshold has 35-mV hysteresis, and the pin also serves as the on-time programming node - requiring careful interface design if both functions are used in the same system.
LM5008ASD/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-WDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Not For New Designs
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 6V
- Voltage - Input (Max):
- 95V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 75V
- Current - Output:
- 350mA
- Frequency - Switching:
- 50kHz ~ 1.1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-WSON (4x4)
LM5008ASD/NOPB FAQ
1.How can I place an order for LM5008ASD/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5008ASD/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 LM5008ASD/NOPB reliable?
The price and inventory of LM5008ASD/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5008ASD/NOPB is usually 5 days.
3.What payment methods are accepted for LM5008ASD/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5008ASD/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM5008ASD/NOPB?
LM5008ASD/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5008ASD/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 LM5008ASD/NOPB?
For technical support, including LM5008ASD/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5008ASD/NOPB requirements.
6.How does Aetrix verify that LM5008ASD/NOPB is sourced from the original manufacturer or authorized distributors?
All LM5008ASD/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 LM5008ASD/NOPB meets industry standards.
7.What is the process for return or replacement of LM5008ASD/NOPB?
All LM5008ASD/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM5008ASD/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 LM5008ASD/NOPB part is unused and in its original packaging.
Return procedure for LM5008ASD/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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