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Texas Instruments LM34910SDX
- Part No.:
- LM34910SDX
- Manufacturer:
- Texas Instruments
- Package:
- 10-WDFN Exposed Pad
- Datasheet:
-
LM34910SDX.pdf
- Description:
- IC REG BUCK ADJ 1.25A 10WSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,198
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Product details
Overview
LM34910SDX from Texas Instruments is a high-voltage, 40V N-channel buck switching regulator with integrated switch, delivering up to 1.25A output current. It operates across 8V–36V input range, features hysteretic control with no loop compensation, and uses a WSON-10 package for thermal efficiency in point-of-load applications.
For engineers reviewing the LM34910SDX datasheet, LM34910SDX pinout, LM34910SDX application, or LM34910SDX equivalent, key selection criteria include its fixed 2.5V feedback reference, valley current limit at 1.25A, adjustable on-time via RON resistor, 280 ns minimum off-time, and thermal shutdown at 175°C.
Technical Context
The LM34910SDX implements a hysteretic regulation scheme using an on-time timer whose duration varies inversely with VIN - enabling near-constant switching frequency across line and load variations. Its internal 7.0V start-up regulator powers control circuitry and gate drivers, while VCC UVLO (5.8V threshold) ensures safe enablement.
Current limiting occurs during off-time by sensing recirculating current at ISEN relative to SGND, with a factory-set 1.25A valley threshold. Over-voltage protection triggers at FB = 2.875V, immediately terminating the on-pulse to safeguard downstream loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8.0V to 36V - supports wide industrial and telecom input rails; absolute max 40V transient tolerance |
| Output Current | 1.25A - valley current limit sets maximum sustainable load without foldback |
| Feedback Reference | 2.5V ±1.2% - precision internal reference enables accurate output voltage setting via R1/R2 divider |
| Switch RDS(on) | 0.45Ω typical - low conduction loss improves efficiency at 1.25A continuous operation |
| Thermal Shutdown | 175°C activation - protects device under overload or poor heatsinking; 20°C hysteresis prevents oscillation |
| Softstart Current | 11.5 µA - charges external SS capacitor linearly to control output ramp rate and reduce inrush stress |
| Minimum Off-Time | 280 ns - ensures sufficient bootstrap capacitor recharge time for reliable high-side gate drive |
Pinout & Package
LM34910SDX is housed in a thermally enhanced 4 mm × 4 mm WSON-10 package with exposed thermal pad for improved heat dissipation. The package is RoHS-compliant, moisture-sensitive level 1, and rated for −40°C to +125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switching Node | Connection point for inductor, freewheeling diode, and BST capacitor; carries full switching current and high dv/dt |
| BST (Pin 2) | Bootstrap Supply | Drives high-side N-channel gate via 0.022 µF capacitor; internal diode recharges it during off-time |
| ISEN (Pin 3) | Current Sense Input | Senses recirculating current during off-time; sets 1.25A valley current limit with internal 130 mΩ sense path |
| SGND (Pin 4) | Sense Ground | Return path for current-sense resistor; must be routed separately from RTN to avoid noise coupling |
| RTN (Pin 5) | Circuit Ground | Reference for internal comparators and logic; connects to system ground but isolated from power return paths |
| FB (Pin 6) | Feedback Input | Compares output voltage (via R1/R2 divider) to 2.5V reference; requires ≥25 mV ripple for stable hysteretic operation |
| SS (Pin 7) | Softstart Control | Internal 11.5 µA current source ramps voltage to 2.5V; grounding disables softstart and forces immediate startup |
| RON/SD (Pin 8) | On-Time Set / Shutdown | Resistor-to-VIN sets on-time; grounding shuts down regulator and discharges SS capacitor |
| VCC (Pin 9) | Start-Up Regulator Output | 7.0V regulated supply for internal circuits; can be externally biased (8–14V) to reduce dissipation |
| VIN (Pin 10) | Main Input Supply | Accepts 8–36V input; powers both buck stage and internal start-up regulator; withstands 40V transients |
Key Features
| Feature | Design Value |
|---|---|
| No loop compensation required | Hysteretic control eliminates external compensation network, reducing BOM count and layout sensitivity |
| Ultra-fast transient response | On-demand switching with 280 ns minimum off-time enables sub-microsecond recovery from load steps |
| Adjustable operating frequency | RON resistor and VIN jointly set on-time, allowing frequency tuning from ~100 kHz to >700 kHz |
| Integrated start-up regulator | Self-biases internal circuitry from VIN; supports direct connection to 36V rail without external bias supply |
| Exposed thermal pad | WSON-10 package includes bottom-side copper pad soldered to PCB ground plane for <15°C/W θJA |
Applications
| High Efficiency Point-of-Load (POL) Regulator | Non-Isolated Telecommunication Buck Regulator |
|---|---|
Use Scenario: Powering FPGA core voltage (e.g., 1.2V @ 1.2A) from a 24V intermediate bus in telecom shelf systems. IC Role / Device Role / Timing Role: Primary buck controller providing regulated DC output; manages switching timing via on-time timer and FB comparator. Use Value: Delivers 1.25A at >90% efficiency with minimal external components; hysteretic control avoids instability under dynamic FPGA load changes. | Use Scenario: Generating 5V/3.3V bias rails from 48V telecom distribution bus in base station power modules. IC Role / Device Role / Timing Role: High-input-voltage step-down regulator; handles 48V transients up to 40V with robust UVLO and thermal protection. Use Value: Eliminates need for pre-regulator stage; 36V max operating input and 40V transient rating simplify front-end design. |
| Secondary High Voltage Post Regulator | Industrial Motor Drive Auxiliary Supply |
Use Scenario: Generating isolated gate driver supply (e.g., 15V @ 0.5A) from a 36V auxiliary rail in servo amplifier designs. IC Role / Device Role / Timing Role: Non-isolated post-regulator stepping down intermediate rail; uses RON resistor to fix switching frequency independent of load. Use Value: Constant-frequency behavior simplifies EMI filtering; valley current limit prevents damage during short-circuit events on gate drive outputs. | Use Scenario: Providing 12V bias for microcontroller, sensors, and interface ICs in 24V/36V industrial motor drives. IC Role / Device Role / Timing Role: Main system bias regulator; leverages VCC self-bias and thermal shutdown for rugged operation in high-ambient environments. Use Value: Operates continuously at 125°C junction temperature; exposed thermal pad enables conduction cooling without heatsink. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDRCRQ1 | Automotive-grade (AEC-Q100), 100V input, 0.6A output, current-mode control with compensation | Requires loop compensation; suited for automotive infotainment and ADAS where 100V transients occur | Choose when automotive qualification, higher input voltage, or tighter output regulation is required over raw cost or simplicity |
| TPS54202DDCR | 4.5–28V input, 2A output, integrated FETs, current-mode control with internal compensation | Lower input voltage ceiling; optimized for 12V/24V systems with higher current demand than LM34910SDX | Prefer when input is ≤28V and 2A output capability is needed without increasing board area or complexity |
Compared with LM5164QDRCRQ1 and TPS54202DDCR, the LM34910SDX offers simpler implementation (no compensation), higher input voltage support (up to 36V), and lower quiescent current, making it optimal for cost-sensitive industrial POL and telecom secondary regulation where 1.25A suffices.
Availability
LM34910SDX is available at Aetrix Electronics and suitable for high-efficiency point-of-load (POL) regulators, non-isolated telecom buck converters, and secondary high-voltage post regulators requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LM34910SDX 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 and embedded processing technologies, with leadership in power management ICs and high-reliability industrial solutions.
The LM34910 product line delivers high-voltage, integrated buck regulators for demanding industrial and telecom applications where simplicity, thermal performance, and transient robustness are critical.
FAQ
What is the maximum input voltage rating for the LM34910SDX?
The LM34910SDX has an absolute maximum input voltage rating of 40V, with recommended operating range from 8.0V to 36V. This allows safe use in 24V and 36V industrial systems with transient overvoltage margins. Exceeding 40V risks permanent damage to the internal N-channel buck switch and gate driver circuitry. Always verify input rail stability and clamp transients within this limit before final design validation.
How does the LM34910SDX achieve stable regulation without external compensation components?
The LM34910SDX uses a hysteretic control architecture that compares the FB pin voltage directly to an internal 2.5V reference. When FB falls below 2.5V, the buck switch turns on for a VIN- and RON-dependent on-time; it remains off until FB drops again. This self-timed, no-loop scheme inherently avoids phase-margin issues and eliminates the need for external RC compensation networks - significantly simplifying layout and improving transient response.
Can the LM34910SDX be used with an external bias supply on the VCC pin?
Yes - the LM34910SDX supports external biasing of the VCC pin with 8V–14V, which disables the internal start-up regulator and reduces power dissipation. This is especially useful in high-input-voltage applications where internal VCC regulation would waste significant power. An external diode must isolate the auxiliary supply from VIN, and the sum of VIN and external VCC must not exceed 50V per absolute maximum ratings.
What is the purpose of the ISEN and SGND pins on the LM34910SDX?
The ISEN pin senses recirculating current through the freewheeling diode during the off-time to implement valley current limiting at 1.25A. SGND serves as the dedicated return path for the current-sense resistor, electrically separated from RTN to prevent noise from corrupting the current measurement. Proper routing - short, direct traces between ISEN, SGND, and the sense resistor - is essential to maintain accurate current limit detection and avoid false triggering.
Does the LM34910SDX support programmable softstart, and how is it implemented?
Yes - the LM34910SDX implements programmable softstart via the SS pin. An internal 11.5 µA current source charges an external capacitor (C6) from 0V to 2.5V, linearly ramping the feedback reference and thus the output voltage. Softstart time is calculated as tSS = (C6 × 2.5V) / 11.5 µA. Grounding SS during operation forces immediate shutdown and discharge; releasing it resumes controlled startup. This prevents inrush current and stabilizes downstream LDOs or microcontrollers.
LM34910SDX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-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):
- 8V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 33V
- Current - Output:
- 1.25A
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-WSON (4x4)
LM34910SDX FAQ
1.How can I place an order for LM34910SDX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM34910SDX 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 LM34910SDX reliable?
The price and inventory of LM34910SDX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM34910SDX is usually 5 days.
3.What payment methods are accepted for LM34910SDX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM34910SDX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM34910SDX?
LM34910SDX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM34910SDX 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 LM34910SDX?
For technical support, including LM34910SDX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM34910SDX requirements.
6.How does Aetrix verify that LM34910SDX is sourced from the original manufacturer or authorized distributors?
All LM34910SDX 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 LM34910SDX meets industry standards.
7.What is the process for return or replacement of LM34910SDX?
All LM34910SDX units undergo pre-shipment inspection (PSI). If there is an issue with LM34910SDX, 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 LM34910SDX part is unused and in its original packaging.
Return procedure for LM34910SDX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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