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Texas Instruments LM2738XSD
- Part No.:
- LM2738XSD
- Manufacturer:
- Texas Instruments
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LM2738XSD.pdf
- Description:
- IC REG BUCK ADJ 1.5A 8WSON
- Quantity:
- Payment:
- Shipping:
Inventory:990
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Product details
Overview
LM2738XSD from Texas Instruments (formerly National Semiconductor) is a monolithic 1.6MHz, 1.5A synchronous step-down DC-DC switching regulator in an 8-pin LLP package. It integrates a 250mΩ NMOS power switch, internal current-mode PWM control, and soft-start circuitry to deliver precise local point-of-load regulation for space-constrained applications such as USB-powered devices and set-top boxes.
For engineers reviewing the LM2738XSD datasheet, LM2738XSD pinout, LM2738XSD application, or LM2738XSD equivalent, key selection considerations include its fixed 1.6MHz switching frequency, 3.0V–20V input range, 0.8V–18V adjustable output, 400nA shutdown current, and thermal shutdown protection at 165°C.
Technical Context
The LM2738XSD employs current-mode PWM control with internal compensation, enabling stable regulation across wide load and line variations without external loop components. Its 1.6MHz fixed-frequency operation supports ultra-small ceramic inductors and capacitors while maintaining up to 90% efficiency at full load.
It features cycle-by-cycle current limiting (2.0A min), undervoltage lockout (2.7V rising threshold), output overvoltage protection (16% above 0.8V reference), and a bootstrap-driven NMOS switch requiring VBOOST–VSW between 2.5V and 5.5V for optimal gate drive.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.6 MHz - enables use of ≤2.2µH inductors and compact 10–22µF ceramic output capacitors. |
| Max Output Current | 1.5 A - continuous regulated load capability with internal 250mΩ NMOS switch. |
| Input Voltage Range | 3.0 V to 20 V - supports wide-input industrial, USB, and battery-powered systems (e.g., 12V rails, Li-ion + LDO-fed inputs). |
| Output Voltage Range | 0.8 V to 18 V - adjustable via external resistor divider; 0.8V ±2% internal reference ensures tight regulation. |
| Shutdown Current | 400 nA - ultra-low quiescent draw preserves battery life in always-on or sleep-mode applications. |
| Thermal Shutdown | 165°C - protects against sustained overload or poor PCB thermal design; auto-recovery at ~150°C. |
| Current Limit | 2.0 A (min) - cycle-by-cycle protection prevents damage during short-circuit or startup inrush. |
Pinout & Package
LM2738XSD is housed in an 8-pin Leadless Leadframe Package (LLP), NSC package code SDA08A, with exposed thermal pad (DAP) connected to GND for enhanced thermal performance. The package measures 3.0 mm × 3.0 mm × 0.8 mm and requires standard reflow soldering (220°C, 15 sec).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - BOOST | Bootstrap supply node | Drives NMOS gate; requires external capacitor between BOOST and SW to generate >2.5V gate overdrive above SW voltage. |
| 2 - VIN | Main power input | Supplies power stage; must be tied to VCC (Pin 3) at package; bypassed with ≥10µF ceramic capacitor. |
| 3 - VCC | IC bias supply | Provides internal logic and control circuitry power; tied to VIN at package; requires local 0.1µF decoupling. |
| 4 - EN | Enable control input | Logic-high (>1.4V) enables regulation; logic-low (<0.4V) disables with 400nA standby current; must not float. |
| 5,7 - GND | Signal & power ground | Low-impedance return path for feedback network and power stage; connect FB resistor ground near these pins. |
| 6 - FB | Feedback sensing input | High-impedance (0.1–100nA bias) node monitoring output via resistor divider; trace must be short and noise-isolated. |
| 8 - SW | Switch node output | Connects to inductor, catch diode cathode, and BOOST capacitor; high dv/dt node requiring minimized loop area. |
| DAP | Thermal pad / GND | Exposed copper pad on bottom; must be soldered to solid PCB GND plane with ≥4 thermal vias for θJA = 60°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 1.6MHz switching | Enables <3mm × 3mm total solution size with 1.0–2.2µH inductors and chip-scale MLCCs - no ferrite core needed. |
| Internal current-mode control | Eliminates need for external compensation components; provides inherent cycle-by-cycle current limiting and fast transient response. |
| Integrated 250mΩ NMOS switch | Reduces BOM count and conduction loss; delivers 1.5A output without external MOSFET or driver IC. |
| 0.8V ±2% internal reference | Supports accurate low-voltage outputs (e.g., 1.2V, 1.8V, 3.3V) with minimal resistor tolerance impact on regulation accuracy. |
| Internal soft-start (600µs) | Controls output ramp rate to limit inrush current into bulk capacitance - critical for hot-swap and battery-fed systems. |
Applications
| USB-Powered Devices | Set-Top Boxes |
|---|---|
Use Scenario: Powering HDMI interface ICs, USB PHYs, and microcontrollers from 5V USB bus with strict EMI and size constraints. IC Role / Device Role / Timing Role: Primary buck regulator delivering clean, regulated 3.3V/1.8V from 5V input; operates at 1.6MHz to avoid USB 2.0 high-speed band (480MHz). Use Value: Compact 3mm × 3mm footprint and integrated switch eliminate discrete FET/driver, reducing layout complexity and radiated noise. |
Use Scenario: Generating core voltage for MPEG decoder SoCs and memory interfaces in consumer STB platforms. IC Role / Device Role / Timing Role: Local point-of-load converter supplying 1.2V @ 1.2A to processor cores with fast load-step response. Use Value: Current-mode control and 1.6MHz frequency ensure <50mV output deviation during 1A load transients - meets STB audio/video stability requirements. |
| Battery-Powered Portable Electronics | HDD Core Power |
Use Scenario: Regulating 3.3V for Wi-Fi modules and sensors in handheld medical or IoT devices powered by single-cell Li-ion (3.0–4.2V). IC Role / Device Role / Timing Role: High-efficiency buck converter operating across full battery range; uses EN pin for system-level power sequencing. Use Value: 400nA shutdown current extends battery runtime in sleep mode; 3.0V minimum input supports deep discharge operation. |
Use Scenario: Supplying 1.2V/1.5A to HDD controller ASICs during spin-up and active read/write phases. IC Role / Device Role / Timing Role: Primary core regulator with thermal shutdown and current limit protecting against motor surge currents. Use Value: 165°C thermal shutdown and 2.0A current limit prevent latch-up during HDD mechanical faults - improves system reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62130ARGTR | 3.0–17V input, 1.2A output, 2.5MHz switching, 17µA quiescent current (non-shutdown) | Higher frequency enables smaller passives but lower max current; lacks 400nA shutdown mode | Preferred when board space is more constrained than current budget; verify thermal margin at 1.5A load. |
| MP2307DN-LF-Z | 4.5–23V input, 3A output, 340kHz switching, 2.5mA quiescent current, no internal soft-start | Higher current rating and wider VIN, but lower frequency increases inductor size and reduces transient response | Choose when >1.5A peak load or >20V input is required; add external soft-start RC if inrush control is critical. |
Compared with TPS62130ARGTR and MP2307DN-LF-Z, the LM2738XSD uniquely balances 1.5A capability, 1.6MHz frequency, and ultra-low 400nA shutdown - making it optimal for USB- and battery-fed systems where standby power and solution size are co-constrained.
Availability
LM2738XSD is available at Aetrix Electronics and suitable for USB-powered devices, set-top boxes, and battery-powered portable electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2738XSD 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 acquired National Semiconductor in 2011 and maintains full technical and manufacturing continuity for legacy analog power products.
The LM2738XSD belongs to TI's high-frequency DC-DC buck regulator family, designed specifically for space- and efficiency-critical point-of-load conversion in consumer, computing, and portable electronics.
FAQ
What is the recommended input capacitor for LM2738XSD?
A 10µF X7R multilayer ceramic capacitor (MLCC) rated for ≥25V is recommended for the LM2738XSD input. It must be placed as close as possible to VIN and VCC pins with short, wide traces and low-ESL layout. For higher ripple current handling, parallel a 0.1µF MLCC. Avoid leaded or high-ESL tantalum capacitors due to instability risk at 1.6MHz.
Does LM2738XSD require an external catch diode?
Yes, the LM2738XSD requires an external Schottky catch diode (e.g., RB050M-30, SS34) connected from SW to GND. Unlike synchronous buck regulators, LM2738XSD uses an internal NMOS switch but relies on an external diode for freewheeling current during the off-time. Diode forward voltage directly impacts efficiency and thermal performance.
Can LM2738XSD operate with input voltage below 3.0V?
No - the LM2738XSD has a guaranteed operating input range of 3.0V to 20V. Its undervoltage lockout activates below 2.7V (rising), and absolute maximum ratings specify −0.5V minimum. Operation below 3.0V risks failure to start or unstable regulation; for sub-3V applications, consider TI's TPS6208x or similar low-VIN buck regulators.
How is output voltage set on LM2738XSD?
The LM2738XSD output voltage is set using a resistor divider from VOUT to FB to GND. With a 0.8V internal reference, VOUT = 0.8V × (1 + R1/R2). A typical design uses R2 = 10kΩ and calculates R1 accordingly (e.g., R1 = 22.5kΩ for 3.3V). FB bias current is ≤100nA, so resistor values should stay below 300kΩ to avoid regulation error.
What thermal design practices are critical for LM2738XSD?
For reliable LM2738XSD operation, the DAP (exposed thermal pad) must be soldered to a solid GND plane with ≥4 thermal vias (0.3mm diameter, spaced ≤1mm apart). Use ≥2 oz copper on inner layers. Keep high-current paths (VIN, SW, VOUT) short and wide. Thermal resistance θJA is 60°C/W on a 3″×3″ 4-layer board - derate power above 85°C ambient.
LM2738XSD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 18V
- Current - Output:
- 1.5A
- Frequency - Switching:
- 1.6MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-WSON (3x3)
LM2738XSD FAQ
1.How can I place an order for LM2738XSD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2738XSD 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 LM2738XSD reliable?
The price and inventory of LM2738XSD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2738XSD is usually 5 days.
3.What payment methods are accepted for LM2738XSD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2738XSD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2738XSD?
LM2738XSD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2738XSD 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 LM2738XSD?
For technical support, including LM2738XSD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2738XSD requirements.
6.How does Aetrix verify that LM2738XSD is sourced from the original manufacturer or authorized distributors?
All LM2738XSD 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 LM2738XSD meets industry standards.
7.What is the process for return or replacement of LM2738XSD?
All LM2738XSD units undergo pre-shipment inspection (PSI). If there is an issue with LM2738XSD, 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 LM2738XSD part is unused and in its original packaging.
Return procedure for LM2738XSD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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