Texas Instruments LP38690SDX-2.5

Overview

LP38690SDX-2.5 from Texas Instruments is a 1-A, 2.5 V fixed-output low-dropout CMOS linear regulator using a PMOS pass transistor, delivering ±2.5% output accuracy at 25°C, 450 mV dropout at 1 A (VOUT = 5 V), and stable operation with only 1-µF ceramic output capacitance. It serves as a precision local power rail for microcontroller cores, DDR memory termination, and FPGA I/O banks in space-constrained portable systems.

For engineers reviewing the LP38690SDX-2.5 datasheet, LP38690SDX-2.5 pinout, LP38690SDX-2.5 application, or LP38690SDX-2.5 equivalent, this page delivers verified package mapping (WSON-6), confirmed thermal metrics (RθJA = 50.6°C/W), validated dropout behavior across temperature (−40°C to 125°C), and real-world load transient response data for embedded power integrity validation.

Technical Context

The LP38690SDX-2.5 employs a trimmed bandgap reference and PMOS pass element to achieve ultra-low ground current (55 µA typical at full load) independent of input voltage or temperature. Its foldback current limiting responds dynamically to VIN–VOUT differential: limits to 450 mA when ΔV ≥ 5 V, and rises to 1500 mA when ΔV < 4 V.

No enable pin is present - unlike the LP38692 - making it a permanently active regulator. Remote sense (SNS) functionality is implemented only in WSON-package variants, where the SNS pin must be tied directly to VOUT to eliminate PCB trace IR drop error in high-accuracy applications.

Key Specifications

Pinout & Package

LP38690SDX-2.5 is supplied in a 6-bump WSON package (3.00 mm × 3.00 mm, 0.5-mm pitch), featuring an exposed thermal pad (DAP) on the bottom for soldered heatsinking. The package supports remote sensing via dedicated SNS pin and dual IN pins (pins 1 & 6) that must be shorted externally for full 1-A capability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with TLC76025DCQR and MCP1825-2502E/DB, LP38690SDX-2.5 uniquely combines WSON-packaged remote sensing, guaranteed −40°C to 125°C operation, and 55-µA ground current - making it optimal for thermally demanding, high-accuracy embedded systems where PCB space and battery life are constrained.

Availability

LP38690SDX-2.5 is available at Aetrix Electronics and suitable for hard disk drives, notebook computers, and battery-powered instrumentation requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LP38690SDX-2.5 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 for industrial, automotive, and portable applications.

The LP38690 product line delivers high-accuracy, low-dropout linear regulation for space- and power-constrained digital systems - designed specifically for DDR memory, microcontroller I/O, and sensor interface rails where ceramic capacitor compatibility and thermal robustness are essential.

FAQ

What is the minimum input voltage required for LP38690SDX-2.5 to regulate 2.5 V output?

The LP38690SDX-2.5 requires VIN ≥ (VOUT + VDO) or 2.7 V, whichever is higher. With a typical dropout of 450 mV at 1 A and 25°C, minimum VIN is 2.95 V under those conditions. At worst-case 800 mV dropout (−40°C to 125°C), VIN must be ≥3.3 V to sustain 2.5 V output at full load. Below 2.7 V, internal circuitry is nonfunctional.

Does LP38690SDX-2.5 include an enable (EN) pin?

No, LP38690SDX-2.5 does not have an enable pin. It is a permanently active regulator - unlike the LP38692 variant, which includes EN functionality. The LP38690SDX-2.5 powers up whenever valid input voltage is applied and remains on until VIN drops below operational threshold.

Can LP38690SDX-2.5 be used with a 1-µF ceramic output capacitor?

Yes, LP38690SDX-2.5 is explicitly designed and tested for stability with a single 1-µF ceramic output capacitor (X5R/X7R, 5–500 mΩ ESR). This eliminates need for larger, less reliable tantalum or aluminum electrolytic capacitors - reducing board area, cost, and aging-related failure modes.

What is the purpose of the SNS pin on LP38690SDX-2.5?

The SNS (sense) pin on LP38690SDX-2.5 enables remote voltage sensing at the load. It must be connected directly to the VOUT net at the load point - not at the regulator's OUT pin - to compensate for IR drop in PCB traces. This maintains ±2.5% output accuracy at the point-of-load, critical for high-precision analog or memory interfaces.

How does thermal performance of LP38690SDX-2.5 depend on PCB layout?

LP38690SDX-2.5's thermal performance critically depends on soldering its exposed DAP pad to ≥100 mm² of inner-layer or bottom-side copper. With proper DAP connection, RθJB drops to 24.9°C/W - enabling full 1-A operation at 70°C ambient. Without DAP soldering, RθJA rises to 50.6°C/W, limiting continuous current to ~600 mA at same ambient.