Texas Instruments LP38690SD-2.5

Overview

LP38690SD-2.5 from Texas Instruments is a 2.5 V fixed-output, 1-A low-dropout CMOS linear regulator using a PMOS pass transistor, delivering ±2.5% output accuracy at 25°C, 450 mV dropout at 1 A (5 VOUT), and stable operation with only 1-µF ceramic output capacitance. It serves as a precision local power rail in space-constrained portable systems requiring low quiescent current and thermal robustness.

For engineers reviewing the LP38690SD-2.5 datasheet, LP38690SD-2.5 pinout, LP38690SD-2.5 application, or LP38690SD-2.5 equivalent, key selection criteria include dropout voltage at 2.5 V output, ground pin current under full load, thermal shutdown threshold, WSON-6 package thermal resistance, and compatibility with 1-µF ceramic capacitors without ESR requirements.

Technical Context

The LP38690SD-2.5 implements a trimmed bandgap reference and PMOS pass element architecture, eliminating DC base drive current and enabling ground pin current of just 55 µA at full load. Its foldback current limiting responds dynamically to VIN–VOUT differential: 450 mA limit when VIN–VOUT > 5 V, scaling to 1500 mA when VIN–VOUT < 4 V.

No enable pin is present-unlike the LP38692-making it a permanently enabled regulator. Remote sense (SNS) functionality is available only on WSON-package variants and requires connection directly to VOUT to compensate for PCB trace IR drop.

Key Specifications

Pinout & Package

The LP38690SD-2.5 is packaged in a 6-pin WSON (NGG) with 3.00 mm × 3.00 mm body and exposed thermal pad (DAP) on bottom. This leadless package delivers low junction-to-board thermal resistance (24.9°C/W) and requires soldering the DAP to a copper plane for thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLS850F0TES/V33 and TPS7A2025PDQNR, the LP38690SD-2.5 uniquely combines 1-A capability, 2.5 V fixed output, remote sense (SNS), and guaranteed –40°C to 125°C operation in a thermally optimized WSON package-making it optimal for industrial and portable applications demanding full-load accuracy and thermal margin.

Availability

LP38690SD-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 guaranteed parametric performance across temperature.

Supply support for LP38690SD-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 designing analog ICs, embedded processors, and system solutions for industrial, automotive, and personal electronics markets.

The LP38690SD-2.5 belongs to TI's low-dropout linear regulator product line, engineered for portable and space-constrained applications needing high accuracy, ultra-low-noise output, and ceramic-capacitor stability without ESR constraints.

FAQ

What is the minimum input voltage required for LP38690SD-2.5 to regulate 2.5 V at 1 A?

The LP38690SD-2.5 requires VIN ≥ (VOUT + VDO). At 1 A and 125°C, its dropout voltage is 800 mV; thus minimum VIN is 3.3 V. At 25°C and 1 A, dropout is 145 mV, so VIN ≥ 2.645 V suffices-but design must accommodate worst-case thermal condition. The device also requires VIN ≥ 2.7 V for internal circuit functionality regardless of dropout.

Does LP38690SD-2.5 have an enable pin, and how is it controlled?

No, LP38690SD-2.5 does not include an enable (EN) pin. It is a permanently enabled regulator-unlike the LP38692 variant. Power state is controlled solely by applying or removing input voltage. If ON/OFF control is required, external MOSFET switching on the IN rail or selection of LP38692SD-2.5 is necessary.

Can LP38690SD-2.5 operate with a 1-µF output capacitor, and what type is recommended?

Yes, LP38690SD-2.5 is explicitly designed and tested for stability with a single 1-µF ceramic output capacitor-no ESR requirement. X5R or X7R dielectrics are recommended for temperature stability and DC bias performance. Tantalum or aluminum electrolytic capacitors are unnecessary and may degrade transient response.

What is the purpose of the SNS pin on LP38690SD-2.5, and how must it be connected?

The SNS (sense) pin on LP38690SD-2.5 enables remote voltage sensing at the load to compensate for IR drop in PCB traces. It must be connected directly to the load-side VOUT node-not the regulator's OUT pin. Leaving SNS unconnected or tying it to OUT disables remote sensing and reverts to local regulation with trace-loss error.

How does thermal performance of LP38690SD-2.5 compare between WSON and TO-252 packages?

LP38690SD-2.5 in WSON-6 offers RθJB = 24.9°C/W, significantly better than TO-252's 29.7°C/W. This 16% lower junction-to-board resistance allows higher sustained current in compact layouts. However, TO-252 provides superior junction-to-ambient (50.5°C/W vs. WSON's 50.6°C/W) when large copper planes are unavailable-making WSON ideal for dense boards with thermal vias, TO-252 for simpler layouts with heatsinking.