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Texas Instruments LM34914SD/NOPB
- Part No.:
- LM34914SD/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LM34914SD/NOPB.pdf
- Description:
- IC REG BUCK ADJ 1.25A 10WSON
- Quantity:
- Payment:
- Shipping:
Inventory:1,419
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Product details
Overview
LM34914SD/NOPB from Texas Instruments is an ultra-small 1.25A step-down switching regulator with intelligent valley current limiting, integrated 44V N-channel buck switch, and constant on-time control architecture. It operates from 8V to 40V input, delivers adjustable output voltage (set via FB pin at 2.5V reference), and targets high-efficiency point-of-load regulation in space-constrained industrial and automotive subsystems.
For engineers reviewing the LM34914SD/NOPB datasheet, LM34914SD/NOPB pinout, LM34914SD/NOPB application, or LM34914SD/NOPB equivalent, key selection criteria include its VIN range (8–40V), valley current limit adaptability to VIN/VOUT, no-loop-compensation design, 1.3 MHz max switching frequency, and WSON-10 thermal pad package for high-power-density DC/DC conversion.
Technical Context
The LM34914SD/NOPB implements a constant on-time (COT) control scheme where tON is inversely proportional to VIN and set by external RRON/SD, enabling near-constant switching frequency across line and load. Its valley current limit dynamically adjusts with both VIN and VOUT to prevent inductor saturation under high-line/high-load conditions.
Operation requires no external loop compensation due to inherent stability of the COT architecture, yielding ultra-fast transient response. The integrated start-up regulator provides 7.0V VCC bias, while gate drive UVLO (4.2V threshold) and thermal shutdown (175°C trip) ensure robust fault protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8.0V to 40V - supports wide-input industrial and automotive rails without pre-regulation. |
| Output Current | 1.25A continuous - rated maximum average load current with thermal derating per θJA = 30°C/W. |
| Switch RDS(on) | 0.33Ω (typ) - low conduction loss enables >90% efficiency at 12V→5V/1A. |
| Feedback Reference | 2.50V ±1.5% - precision internal reference sets output via resistor divider on FB pin. |
| Max Switching Frequency | 1.3 MHz - enables compact magnetics and high-frequency filtering for EMI-sensitive applications. |
| Valley Current Limit | 0.9A–1.4A (VIN/VOUT dependent) - adaptive threshold reduces peak inductor current during overload. |
| Soft-Start Time | Programmable via SS capacitor - internal 12.5µA current source charges external cap to 2.5V. |
Pinout & Package
LM34914SD/NOPB is housed in a thermally enhanced 3 mm × 3 mm WSON-10 package with exposed thermal pad (EP) for PCB ground connection. The package supports high power density and efficient heat dissipation in compact layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SW | Switching Node | Connects to inductor, diode cathode, and BST capacitor - carries high dv/dt switching waveform. |
| 2 BST | Bootstrap Supply | Charges external 0.022µF capacitor from VCC during off-time to drive high-side gate. |
| 3 ISEN | Current Sense Input | Senses recirculating inductor current during off-time for valley current limit detection. |
| 4 SGND | Sense Ground | Reference for current sense amplifier - must be routed separately from power ground. |
| 5 RTN | Circuit Ground | Ground return for internal regulation and comparators - connects to system ground plane. |
| 6 FB | Feedback Input | Compares output voltage (via resistor divider) to 2.5V reference for regulation. |
| 7 SS | Soft-Start Control | Internal 12.5µA current source ramps voltage to 2.5V to control output rise time. |
| 8 RON/SD | On-Time Set / Shutdown | Resistor to VIN sets tON; grounding disables regulator and discharges SS capacitor. |
| 9 VCC | Startup Regulator Output | 7.0V regulated supply for internal circuitry; can be externally biased to reduce dissipation. |
| 10 VIN | Main Input Supply | 8V–40V input rail - powers switch and internal logic; bypassed with 0.1µF ceramic capacitor. |
| EP | Exposed Thermal Pad | Internally connected to substrate - must be soldered to PCB ground plane for thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| No loop compensation required | Constant on-time control eliminates need for external compensation network - simplifies layout and improves transient response. |
| Intelligent valley current limit | Threshold varies with VIN and VOUT - prevents inductor saturation and enables smooth transition to constant-current mode during overload. |
| Programmable soft-start | External capacitor on SS pin sets controlled output ramp - avoids inrush current and voltage overshoot at startup. |
| Integrated start-up regulator | 7.0V VCC output powers internal circuitry - allows operation directly from high-VIN rails without external bias supply. |
| Thermal shutdown with hysteresis | 175°C trip / 155°C recovery - protects device during sustained overload or poor heatsinking without oscillation. |
Applications
| Industrial PLC I/O Module Power | Automotive Body Control Unit (BCU) |
|---|---|
Use Scenario: Powers 3.3V or 5V microcontroller, CAN transceiver, and sensor interfaces in DIN-rail mounted PLC modules with 24V DC input. IC Role / Device Role / Timing Role: Primary non-isolated buck regulator delivering stable 1.25A POL supply; regulates against 24V bus ripple and load transients. Use Value: Constant on-time control ensures fast load-step response (<10 µs) to digital I/O switching events without output droop. | Use Scenario: Supplies 5V rail to door module ECUs in 12V/24V automotive systems, operating across cold-crank (6.5V) to load-dump (40V) conditions. IC Role / Device Role / Timing Role: High-voltage buck controller with adaptive current limit - maintains regulation during battery voltage transients and motor stall currents. Use Value: Valley current limit reduction at high VIN prevents inductor saturation during load-dump, avoiding thermal runaway. |
| Point-of-Load for FPGA Core Voltage | Secondary Post-Regulator in Telecom PSU |
Use Scenario: Generates 1.2V core supply for mid-range FPGAs from a 5V or 12V intermediate bus in telecom baseband cards. IC Role / Device Role / Timing Role: Compact, high-frequency buck regulator with programmable soft-start - meets FPGA power sequencing requirements. Use Value: 1.3 MHz switching enables use of small 1.0 µH inductors and low-ESR ceramic capacitors, minimizing board area. | Use Scenario: Provides isolated 3.3V/2A auxiliary supply from a 48V telecom rectifier output, replacing linear regulators in legacy designs. IC Role / Device Role / Timing Role: Secondary non-isolated buck stage after primary isolation - handles high input-to-output differential efficiently. Use Value: 40V absolute max VIN rating and 0.33Ω RDS(on) enable >88% efficiency at 48V→3.3V/2A, reducing thermal load vs. LDOs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | Automotive-grade (AEC-Q100), wider 4.5–100V input, higher 1.5A output, but requires external compensation. | Qualified for automotive powertrain and ADAS; supports higher VIN and longer lifetime reliability testing. | Choose for automotive safety-critical systems requiring AEC-Q100 qualification and extended input range. |
| TPS54202DDCR | Lower 4.5–28V input, 2A output, integrated compensation, smaller 6-pin SOT-23 package. | Better suited for low-VIN consumer and computing applications; lacks valley current limit adaptability. | Choose for cost-sensitive, space-constrained designs below 28V input where adaptive current limiting is not required. |
Compared with LM5164QDDARQ1 and TPS54202DDCR, the LM34914SD/NOPB uniquely combines 8–40V operation, adaptive valley current limiting, and zero-compensation design in a 3×3mm WSON package - making it optimal for industrial POL where fast transients, thermal density, and input range flexibility are prioritized over automotive qualification or ultra-low VIN support.
Availability
LM34914SD/NOPB is available at Aetrix Electronics and suitable for industrial PLC power supplies, automotive body control units, FPGA point-of-load regulation, and telecom secondary post-regulators requiring stable component supply across extended temperature and voltage ranges.
Supply support for LM34914SD/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-reliability power conversion solutions.
The LM34914SD/NOPB belongs to TI's high-voltage buck regulator product line, designed specifically for compact, high-efficiency DC/DC conversion in industrial and automotive environments where wide input range and fast transient response are critical.
FAQ
What is the minimum input voltage required for reliable startup of the LM34914SD/NOPB?
The LM34914SD/NOPB requires VIN ≥ 9V to initiate startup and regulate VCC to 7.0V. Below 9V, the internal start-up regulator cannot establish sufficient bias, causing UVLO on VCC (trip threshold 5.7V). Once running, the device sustains operation down to 8.0V VIN, but initial turn-on fails below 9V. This behavior is confirmed in the Electrical Characteristics table under "VCC Regulated Output" and "UVLOVCC Threshold".
How does the valley current limit of the LM34914SD/NOPB change with output voltage?
The valley current limit threshold of the LM34914SD/NOPB decreases as the FB pin voltage drops - i.e., as VOUT decreases. For example, at VIN = 30V, the limit is 1.1A when VFB = 2.4V (≈5.9V VOUT), but falls to 1.05A when VFB = 1.0V (≈2.5V VOUT). This relationship is explicitly plotted in Figure 5 ("Valley Current Limit Threshold vs. VFB and VIN") and verified in the Electrical Characteristics table under "ILIM" test conditions.
Can the LM34914SD/NOPB operate without an external bootstrap capacitor?
No - the LM34914SD/NOPB requires a 0.022 µF ceramic capacitor between BST and SW pins. This capacitor supplies gate drive energy to the integrated N-channel buck switch during each on-time. Without it, the gate voltage collapses, preventing proper switch conduction. The datasheet mandates this component in the PIN DESCRIPTIONS section for BST and in the Typical Application Circuit, and specifies C4 = 0.022 µF in the APPLICATIONS INFORMATION section.
What is the purpose of the SGND pin on the LM34914SD/NOPB, and how should it be routed?
The SGND pin on the LM34914SD/NOPB serves as the dedicated ground reference for the current sense amplifier that monitors recirculating inductor current at the ISEN pin. It must be routed as a separate, low-impedance path to the sense resistor's ground side - not tied directly to RTN or power ground - to avoid noise coupling into the current limit comparator. This routing requirement is specified in the "PC BOARD LAYOUT" section and reinforced in the PIN DESCRIPTIONS table.
Does the LM34914SD/NOPB support external synchronization of its switching frequency?
No - the LM34914SD/NOPB does not support external frequency synchronization. Its switching frequency is determined solely by the constant on-time control scheme, which depends on VIN and the RON/SD resistor value. There is no SYNC, CLKIN, or FREQ pin, and the datasheet contains no mention of synchronization capability in Features, Functional Description, or Applications Information sections.
LM34914SD/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 37V
- Current - Output:
- 1.25A
- Frequency - Switching:
- 1.3MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-WSON (3x3)
LM34914SD/NOPB FAQ
1.How can I place an order for LM34914SD/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM34914SD/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 LM34914SD/NOPB reliable?
The price and inventory of LM34914SD/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM34914SD/NOPB is usually 5 days.
3.What payment methods are accepted for LM34914SD/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM34914SD/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM34914SD/NOPB?
LM34914SD/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM34914SD/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 LM34914SD/NOPB?
For technical support, including LM34914SD/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM34914SD/NOPB requirements.
6.How does Aetrix verify that LM34914SD/NOPB is sourced from the original manufacturer or authorized distributors?
All LM34914SD/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 LM34914SD/NOPB meets industry standards.
7.What is the process for return or replacement of LM34914SD/NOPB?
All LM34914SD/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM34914SD/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 LM34914SD/NOPB part is unused and in its original packaging.
Return procedure for LM34914SD/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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