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Texas Instruments LM5008SD
- Part No.:
- LM5008SD
- Manufacturer:
- Texas Instruments
- Package:
- 8-WDFN Exposed Pad
- Datasheet:
-
LM5008SD.pdf
- Description:
- IC REG BUCK ADJ 350MA 8WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,594
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Product details
Overview
LM5008SD from Texas Instruments is a 95-V input, 350-mA constant-on-time buck switching regulator with integrated 100-V N-channel MOSFET, internal 7-V VCC regulator, and programmable current-limit off-time. It delivers regulated DC output in non-isolated telecom and automotive post-regulation applications with no loop compensation required.
For engineers reviewing the LM5008SD datasheet, LM5008SD pinout, LM5008SD application, or LM5008SD equivalent, key selection criteria include input voltage range (9.5–95 V), FB reference (2.5 V), minimum off-time (300 ns), thermal shutdown threshold (165°C), and RON/SD dual-function pin for on-time setting and remote shutdown.
Technical Context
The LM5008SD uses a hysteretic constant-on-time (COT) control architecture where on-time varies inversely with VIN via external RON, enabling near-constant frequency across line and load variations. Its regulation relies on a 2.5-V internal reference compared against FB voltage, with overvoltage protection triggered at 2.875 V.
Current limiting employs an intelligent off-timer whose duration depends on both RCL resistor value and FB voltage-preset to 35 µs at short-circuit (FB = 0 V) and scaling down under partial overload. The bootstrap gate driver supports high-side N-MOSFET operation using a 0.01-µF BST–SW capacitor and requires ≥300 ns minimum off-time for reliable recharge.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 9.5 V to 95 V - supports wide-range industrial and telecom rails including 48-V systems with transient tolerance up to 100 V. |
| Output Current | 350 mA DC - maximum continuous load capability with integrated 100-V N-MOSFET and RDS(on) = 1.15 Ω (typ) at 25°C. |
| Feedback Reference | 2.5 V - precision internal reference used to regulate output via external resistor divider; bias current ≤100 nA. |
| Minimum Off-Time | 300 ns - ensures sufficient time for BST capacitor recharge and defines lowest operating frequency boundary. |
| Thermal Shutdown | 165°C with 25°C hysteresis - automatically disables switch and VCC regulator to prevent junction damage; resumes at ~140°C. |
| Current Limit Threshold | 0.51 A (typ) at 25°C - triggers forced off-time scaled by RCL and FB voltage to maintain short-circuit safety without excessive foldback. |
| VCC Regulator | 7 V ±0.4 V - powers internal gate driver and logic; internally current-limited to 9.5 mA; shuts down if externally biased above 7 V. |
Pinout & Package
LM5008SD is available in thermally enhanced 8-pin WSON (NGU) package (4.00 mm × 4.00 mm) with exposed pad connected to system ground for improved thermal performance (RθJA = 42°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SW | Switching node | Power switching output connected to inductor, freewheeling diode, and BST capacitor; handles full pulsed current. |
| 2 BST | Bootstrap supply | Input to floating gate driver; requires 0.01-µF ceramic cap to SW; charged via internal diode from VCC during off-time. |
| 3 RCL | Current limit off-time set | Resistor-to-RTN sets intelligent off-time duration; scales from 35 µs (short-circuit) down as FB rises. |
| 4 RTN | Ground reference | Common return for feedback, current limit, and shutdown circuits; must be low-impedance connection to system ground. |
| 5 FB | Feedback input | Inverting input of regulation comparator; compares output voltage (via resistor divider) to 2.5-V reference. |
| 6 RON/SD | On-time set / shutdown | Resistor-to-VIN sets on-time inversely proportional to VIN; pulled low (<0.7 V) enables remote shutdown mode. |
| 7 VCC | Bias supply output | Internally regulated 7-V rail powering gate driver and control logic; decoupled with 0.1-µF ceramic capacitor. |
| 8 VIN | Main input supply | High-voltage input (9.5–95 V); powers internal startup regulator and supplies energy to buck stage. |
Key Features
| Feature | Design Value |
|---|---|
| No loop compensation required | Hysteretic COT control eliminates need for external compensation network, reducing BOM count and design iteration time. |
| Intelligent current limit protection | Off-time dynamically adjusted by RCL and FB voltage - ensures robust short-circuit handling while minimizing foldback during moderate overloads. |
| Ultra-fast transient response | Fixed on-time + hysteretic regulation enables immediate reaction to load steps without phase-margin concerns or stability tuning. |
| Integrated 100-V N-channel buck switch | Reduces solution size and component count; eliminates external high-voltage MOSFET and associated gate drive complexity. |
| Self-biased VCC option | VCC pin accepts auxiliary 8–14 V supply to disable internal series regulator, lowering power dissipation in high-VIN applications. |
Applications
| Telecom Power Supply | Automotive Post-Regulator |
|---|---|
Use Scenario: Step-down 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 non-isolated buck regulator delivering stable output with fast transient response to digital load changes. Use Value: Enables compact, high-efficiency power delivery across wide input range without optocoupler feedback or compensation components. | Use Scenario: Secondary regulation in 48-V mild-hybrid vehicle systems powering infotainment or ADAS sensors. IC Role / Device Role / Timing Role: High-input-voltage buck converter providing isolated-subsystem power with built-in thermal and overcurrent protection. Use Value: Supports ASIL-compliant designs via 165°C thermal shutdown and intelligent current limit that avoids destructive latch-up during fault conditions. |
| Industrial Sensor Interface | Smart Meter Power Rail |
Use Scenario: Generating 3.3-V supply from unregulated 24-V field bus for analog sensor signal conditioning and microcontroller operation. IC Role / Device Role / Timing Role: Low-quiescent-current buck regulator operating in DCM at light loads to extend battery life in wireless sensor nodes. Use Value: Maintains >85% efficiency at 1-mA load due to discontinuous conduction mode and 76-µA shutdown current. | Use Scenario: Powering metrology ICs and RF modules from 12–95 V AC/DC rectified input in utility smart meters. IC Role / Device Role / Timing Role: Input-tolerant DC/DC converter ensuring stable 5-V rail despite wide-line fluctuations and surge transients. Use Value: Withstands 100-V transients and provides precise 2.5-V reference for accurate ADC biasing in revenue-grade metering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | Automotive-grade AEC-Q100 qualified; wider 4.5–100 V input; higher 500-mA output; integrated soft-start and spread-spectrum. | Required for functional-safety automotive systems; supports higher load and tighter EMI control. | Select when AEC-Q100 compliance, higher current, or EMI reduction is mandatory. |
| MAX5033BASA+ | Lower 76-V max input; 250-mA output; fixed-frequency PWM (not COT); no BST pin or integrated high-side switch. | Suitable for cost-sensitive industrial supplies where lower voltage range and simpler layout are acceptable. | Choose for legacy designs needing fixed-frequency control and minimal external components beyond basic passives. |
Compared with LM5008SD, LM5164QDDARQ1 offers automotive qualification and higher current but adds complexity and cost; MAX5033BASA+ simplifies layout and reduces input range but lacks COT responsiveness and integrated high-side switch capability.
Availability
LM5008SD is available at Aetrix Electronics and suitable for telecom power supplies, automotive post-regulators, industrial sensor interfaces, and smart meter power rails requiring stable component supply across extended temperature and input voltage ranges.
Supply support for LM5008SD 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 designing analog and embedded processing solutions for industrial, automotive, and communications markets.
The LM5008SD belongs to TI's high-voltage DC/DC converter product line, engineered for simple, efficient step-down regulation from unregulated 12–95 V inputs in space-constrained applications.
FAQ
What is the minimum input voltage required for reliable startup of the LM5008SD?
The LM5008SD requires a minimum input voltage of 9.5 V to initiate startup. Below this level, the internal VCC regulator cannot reach its 6.3-V undervoltage lockout threshold, preventing activation of the buck switch. This specification is verified across –40°C to 125°C junction temperature and confirmed in Section 6.3 of the official LM5008SD datasheet.
How does the LM5008SD implement remote shutdown functionality?
The LM5008SD implements remote shutdown via the RON/SD pin: pulling this pin below 0.7 V (with hysteresis of 35 mV) disables both the internal VCC regulator and buck switch, reducing quiescent current to 76 µA (typ). This function is electrically distinct from on-time programming and operates independently of RON resistor value, as documented in Section 7.3.5 and Table 6.5 of the LM5008SD datasheet.
Can the LM5008SD operate without an external bootstrap capacitor?
No, the LM5008SD cannot operate without an external 0.01-µF ceramic capacitor between BST and SW pins. This capacitor supplies gate drive voltage to the internal N-channel MOSFET during the on-time; absence causes immediate gate drive failure and switch malfunction. The minimum 300 ns off-time is specifically designed to ensure adequate recharge of this capacitor, as specified in Section 7.3.7 of the LM5008SD datasheet.
What is the purpose of the RCL pin on the LM5008SD, and how does it affect protection behavior?
The RCL pin on the LM5008SD sets the duration of the forced off-time during current-limit events. Connected to RTN via a resistor, it determines off-time using the formula Toff = 10–5 / (0.285 + (FB / 6.35×10–6 × RCL)). At FB = 0 V (e.g., output short), off-time is fixed at 35 µs; as FB rises, off-time decreases proportionally-reducing foldback and improving recovery. This behavior is confirmed in Section 7.3.6 and Table 6.5 of the LM5008SD datasheet.
Does the LM5008SD require output capacitor ESR for stable regulation, and why?
Yes, the LM5008SD requires a minimum ESR in the output capacitor to generate sufficient ripple voltage (25–50 mV peak-to-peak at FB) for proper hysteretic regulation. Without it, the feedback comparator lacks the necessary AC signal to trigger on-time pulses reliably. If low-ESR ceramics are used, a small series resistor (R3 in Figure 7) must be added to restore required ripple, as explicitly stated in Section 7.3.1 of the LM5008SD datasheet.
LM5008SD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-WDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 9.5V
- Voltage - Input (Max):
- 95V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 75V
- Current - Output:
- 350mA
- Frequency - Switching:
- 50kHz ~ 600kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-WSON (4x4)
LM5008SD FAQ
1.How can I place an order for LM5008SD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5008SD 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 LM5008SD reliable?
The price and inventory of LM5008SD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5008SD is usually 5 days.
3.What payment methods are accepted for LM5008SD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5008SD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM5008SD?
LM5008SD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5008SD 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 LM5008SD?
For technical support, including LM5008SD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5008SD requirements.
6.How does Aetrix verify that LM5008SD is sourced from the original manufacturer or authorized distributors?
All LM5008SD 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 LM5008SD meets industry standards.
7.What is the process for return or replacement of LM5008SD?
All LM5008SD units undergo pre-shipment inspection (PSI). If there is an issue with LM5008SD, 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 LM5008SD part is unused and in its original packaging.
Return procedure for LM5008SD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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