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Texas Instruments LM34914SDX
- Part No.:
- LM34914SDX
- Manufacturer:
- Texas Instruments
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LM34914SDX.pdf
- Description:
- IC REG BUCK ADJ 1.25A 10WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,526
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Product details
Overview
LM34914SDX from Texas Instruments is an ultra-small, high-voltage synchronous step-down switching regulator IC with integrated 44V N-channel buck switch, valley current limiting, and constant on-time control. It delivers up to 1.25A output current across 8V–40V input range, operates at up to 1.3 MHz, requires no loop compensation, and targets point-of-load regulation in space-constrained industrial and automotive power supplies.
For engineers reviewing the LM34914SDX datasheet, LM34914SDX pinout, LM34914SDX application, or LM34914SDX equivalent, this page provides verified technical context, validated pin functions, confirmed operating parameters, real-world application mappings, and two rigorously cross-checked alternative parts for high-voltage POL designs.
Technical Context
The LM34914SDX implements a constant on-time (COT) control architecture where tON is inversely proportional to VIN and set by RON/SD, enabling near-constant switching frequency (1.3 MHz typical) across line and load variations. Its valley current limit dynamically scales with VIN and VFB to prevent inductor saturation under high-line/high-load conditions.
It integrates a self-biased 7.0V startup regulator (VCC), bootstrap gate drive (BST/SW), precision 2.5V reference (FB), programmable soft-start (SS), and thermal shutdown (175°C). The ISEN/SGND sensing path enables cycle-by-cycle current limiting without external sense resistors, while the RON/SD pin provides both on-time programming and shutdown control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8.0 V to 40 V - supports wide-range industrial and automotive battery-fed rails without pre-regulation. |
| Output Current | 1.25 A continuous - sufficient for mid-power POL loads such as microcontrollers, FPGAs, and analog subsystems. |
| Switching Frequency | Up to 1.3 MHz - enables compact magnetics and low-profile ceramic output capacitors. |
| Feedback Reference | 2.50 V ±1.5% - sets regulated output via external resistor divider; enables adjustable outputs from ~2.7 V to >30 V. |
| Valley Current Limit | 0.9 A to 1.4 A (VIN/VFB-dependent) - prevents inductor saturation and overcurrent damage without foldback. |
| Thermal Shutdown | 175°C with 20°C hysteresis - protects against sustained overload or poor PCB thermal design. |
| Package | WSON-10 (3 mm × 3 mm, exposed thermal pad) - optimized for high power density and thermal performance in tight layouts. |
Pinout & Package
LM34914SDX is housed in a thermally enhanced 10-pin WSON package (3 mm × 3 mm) with an exposed metal pad (EP) connected internally to substrate ground and intended for soldering to PCB ground plane to improve heat dissipation. Pin numbering follows standard counter-clockwise order starting from top-left corner (pin 1 = SW).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SW | Switching node | Connects to inductor, freewheeling diode cathode, and BST capacitor - carries high di/dt pulsed current; requires short, low-inductance routing. |
| 2 BST | Bootstrap supply | Charges 0.022 µF capacitor during off-time via internal diode; supplies gate drive voltage for high-side N-MOSFET. |
| 3 ISEN | Current sense return | Sinks recirculating inductor current during off-time; used by internal comparator for valley current limit detection. |
| 4 SGND | Sense ground | Reference for current-sense path only; must be routed separately from power ground to avoid noise coupling into ISEN. |
| 5 RTN | Circuit ground | Ground reference for internal bias circuits, FB comparator, and SS ramp - connects to system ground near C3/C5. |
| 6 FB | Feedback input | Compares output voltage (via resistor divider) to 2.5 V reference; regulates VOUT; requires ≥25 mVp-p ripple for stable operation. |
| 7 SS | Soft-start ramp | Internal 12.5 µA current source charges external capacitor to 2.5 V; controls output voltage rise time and inrush current. |
| 8 RON/SD | On-time programming & shutdown | Resistor-to-VIN sets tON; grounding disables regulator - dual-function pin requiring careful layout to avoid false shutdown. |
| 9 VCC | Startup regulator output | 7.0 V regulated supply for internal circuitry; can be externally powered (8–14 V) to reduce dissipation; bypassed with 0.1 µF to RTN. |
| 10 VIN | Main input supply | Accepts 8–40 V; powers internal circuits and buck switch; requires local 0.1 µF ceramic (C5) and bulk capacitor (C1) close to pins. |
Key Features
| Feature | Design Value |
|---|---|
| No loop compensation required | Constant on-time control eliminates external compensation network - reduces BOM count and design iteration time. |
| Valley current limit scaling | Threshold adjusts with VIN and VFB - maintains safe peak inductor current across full input/output operating range. |
| Ultra-fast transient response | Load step recovery within microseconds - enabled by COT architecture and absence of phase-margin constraints. |
| Programmable soft-start | External capacitor sets controlled VOUT ramp time - prevents inrush current and overshoot during power-up. |
| Integrated 44V N-channel buck switch | RDS(on) = 0.33 Ω (typ) - eliminates external MOSFET and driver, reducing footprint and parasitic losses. |
| Thermally enhanced WSON-10 | θJA = 30 °C/W (4-layer board) - enables 1.25A operation without heatsink in compact industrial PCBs. |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
|
Use Scenario: Regulating 12 V battery rail to 3.3 V for microcontroller, CAN transceiver, and sensor interface circuitry in harsh under-hood environments. IC Role / Device Role / Timing Role: Primary non-isolated buck converter providing stable, low-noise 3.3 V supply with fast transient response to handle CAN bus arbitration spikes. Use Value: 8–40 V input range accommodates cold-crank (6.5 V) and load-dump (40 V) events; valley current limit prevents latch-up during short-circuit faults. |
Use Scenario: Generating 5 V from 24 V truck battery for infotainment display backlight drivers and USB charging ports. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator delivering up to 1.25 A with minimal thermal rise in confined dashboard space. Use Value: WSON-10 package with exposed pad enables direct thermal coupling to chassis ground; 1.3 MHz switching avoids AM radio band interference. |
| Telecom Remote Radio Unit | Factory Automation Sensor Hub |
|
Use Scenario: Converting 48 V PoE++ or DC distribution rail to 1.8 V/3.3 V for FPGA configuration, RF front-end bias, and ADC reference supplies. IC Role / Device Role / Timing Role: Secondary high-voltage post-regulator handling wide-input transients and delivering tightly regulated low-voltage rails. Use Value: No-loop-compensation design ensures stability with ceramic output caps; 2.5 V reference tolerance (±1.5%) supports <1% total output error budget. |
Use Scenario: Powering multiple isolated analog sensor signal chains (4–20 mA transmitters, RTD interfaces) from a centralized 24 V fieldbus supply. IC Role / Device Role / Timing Role: Compact, robust buck regulator supplying clean 5 V for op-amps, references, and isolation barrier ICs in dusty, vibration-prone enclosures. Use Value: Thermal shutdown (175°C) and VCC UVLO (5.7 V) provide fault resilience; RON/SD pin allows remote enable/disable via PLC digital output. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | Automotive-grade (AEC-Q100), 3.5–65 V input, 1 A, integrated 100 V MOSFET, requires external compensation. | Supports higher input (65 V) and automotive qualification; lower max current; slower transient response due to voltage-mode control. | Choose for automotive safety-critical systems requiring AEC-Q100 Grade 1 and extended input range. |
| TPS54160DGQR | 6–60 V input, 1.5 A, current-mode control, requires external compensation, larger SOIC-8 package. | Higher max current and wider input range; needs compensation network and larger layout area; less efficient at light loads. | Choose when needing >1.25 A output or compatibility with legacy SOIC-8 footprints and current-mode design workflows. |
Compared with LM34914SDX, LM5164QDDARQ1 adds automotive qualification and higher VIN but sacrifices transient speed and integration; TPS54160DGQR offers higher current and input range but increases design complexity and board area due to external compensation and larger package.
Availability
LM34914SDX is available at Aetrix Electronics and suitable for industrial PLCs, automotive body controllers, telecom remote radio units, and factory automation sensor hubs requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM34914SDX 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 expertise in high-reliability power conversion ICs.
The LM34914SDX belongs to TI's high-voltage buck regulator product line, designed specifically for compact, high-efficiency point-of-load regulation in industrial, automotive, and telecom applications where wide input range and fast transient response are critical.
FAQ
What is the maximum output current capability of the LM34914SDX?
The LM34914SDX delivers up to 1.25 A of continuous output current under typical thermal conditions (θJA = 30 °C/W, TA = 25 °C). Peak switch current is rated at 2 A, and average current in current-limit mode is capped at 1.5 A. Actual achievable current depends on PCB layout, ambient temperature, and input/output voltage differential - full 1.25 A is confirmed at VIN = 12 V, VOUT = 5 V with proper thermal pad connection.
Does the LM34914SDX require external compensation components?
No, the LM34914SDX uses a constant on-time (COT) control architecture that eliminates the need for external compensation networks. Its feedback loop is inherently stable with ceramic output capacitors, simplifying design and reducing bill-of-materials cost. This is explicitly confirmed in the datasheet Feature list ("No Loop Compensation Required") and Functional Description section.
How does the valley current limit function in the LM34914SDX?
The LM34914SDX monitors recirculating current at the ISEN pin during the off-time to detect valley current threshold crossing. The threshold varies with VIN and VFB (e.g., 1.0–1.4 A depending on operating point) to prevent inductor saturation. When triggered, it reduces on-time by ~50% cycle-by-cycle until regulation resumes - a behavior verified in the "Current Limit" section and Figure 10 of the SNVS453B datasheet.
What is the purpose of the RON/SD pin on the LM34914SDX?
The RON/SD pin serves two distinct functions: (1) connecting an external resistor between VIN and RON/SD sets the on-time (and thus switching frequency); (2) pulling RON/SD below 0.8 V places the LM34914SDX into shutdown mode, disabling the switch, halting soft-start, and reducing quiescent current to ≤160 µA. Both behaviors are specified in the PIN DESCRIPTIONS and Shutdown sections of the datasheet.
Can the LM34914SDX operate with an input voltage below 8 V?
No - the absolute minimum operating input voltage for the LM34914SDX is 8.0 V, as defined in the Operating Ratings table. Below this, the internal startup regulator cannot establish VCC ≥ 5.7 V (UVLO threshold), and the buck switch remains disabled. Attempting operation below 8 V may result in erratic behavior or failure to start, per the Absolute Maximum Ratings and Functional Description.
LM34914SDX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-WFDFN 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):
- 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)
LM34914SDX FAQ
1.How can I place an order for LM34914SDX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM34914SDX 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 LM34914SDX reliable?
The price and inventory of LM34914SDX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM34914SDX is usually 5 days.
3.What payment methods are accepted for LM34914SDX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM34914SDX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM34914SDX?
LM34914SDX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM34914SDX 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 LM34914SDX?
For technical support, including LM34914SDX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM34914SDX requirements.
6.How does Aetrix verify that LM34914SDX is sourced from the original manufacturer or authorized distributors?
All LM34914SDX 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 LM34914SDX meets industry standards.
7.What is the process for return or replacement of LM34914SDX?
All LM34914SDX units undergo pre-shipment inspection (PSI). If there is an issue with LM34914SDX, 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 LM34914SDX part is unused and in its original packaging.
Return procedure for LM34914SDX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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