Texas Instruments LP38693SDX-ADJ

Overview

LP38693SDX-ADJ from Texas Instruments is a 500-mA adjustable-output CMOS low-dropout linear regulator with enable (EN) pin, stable using ≥1-µF ceramic output capacitors, 2% ADJ-pin reference accuracy (1.25 V), and 250 mV typical dropout at 500 mA (5-V output). It operates across 2.7 V to 10 V input and delivers 1.25 V to 9 V output - used in notebook computers for core voltage regulation under dynamic load.

For engineers reviewing the LP38693SDX-ADJ datasheet, LP38693SDX-ADJ pinout, LP38693SDX-ADJ application, or LP38693SDX-ADJ equivalent, key selection criteria include EN-controlled shutdown capability, thermal shutdown activation at 160°C, foldback current limiting dependent on VIN–VOUT differential, GND-pin current ≤55 µA at full load, and compatibility with ultra-low-ESR ceramic capacitors down to 5 mΩ.

Technical Context

The LP38693SDX-ADJ uses a PMOS pass transistor enabling near-zero DC base drive current, ensuring GND-pin current remains ≤100 µA across load, input voltage, and temperature. Its precision trimmed 1.25-V bandgap reference supports 2% ADJ-pin voltage accuracy over –40°C to +125°C.

It integrates thermal shutdown (160°C activation, 10°C hysteresis), foldback current limiting (350 mA limit when VIN–VOUT > 5 V; 850 mA when < 4 V), and 1-µA off-state quiescent current. The EN pin provides logic-level control without internal pullup/pulldown, requiring external termination.

Key Specifications

Pinout & Package

SOT-223 (5-pin) package with exposed thermal pad (DAP) on bottom; thermally enhanced for high ambient operation up to +125°C junction temperature. Pin 1 = IN, Pin 2 = ADJ, Pin 3 = OUT, Pin 4 = GND (thermally connected), Pin 5 = EN.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable LDO regulator applications.

Compared with TPL7407LPGEDR and TPS7A2025PDQNR, LP38693SDX-ADJ uniquely combines adjustable output (1.25–9 V), EN control, ceramic-cap stability, and low dropout in a single SOT-223 package - making it optimal for multi-voltage embedded systems requiring design reuse across platforms.

Availability

LP38693SDX-ADJ is available at Aetrix Electronics and suitable for notebook computers, battery-powered instrumentation, and portable medical devices requiring stable component supply, long-term lifecycle support, and automotive-grade temperature validation.

Supply support for LP38693SDX-ADJ 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, embedded processing, and connectivity technologies, with leadership in power management ICs since the 1980s.

The LP3869x-ADJ product line was designed for portable, battery-powered digital systems requiring fast start-up, low quiescent current, and ceramic-capacitor compatibility - targeting space- and energy-constrained applications like notebooks and handheld instruments.

FAQ

What is the minimum output capacitor required for stable operation of LP38693SDX-ADJ?

The LP38693SDX-ADJ is stable with a minimum 1-µF ceramic output capacitor having ESR between 5 mΩ and 500 mΩ. X7R or X5R dielectrics are recommended to maintain capacitance across voltage and temperature. Using lower values risks oscillation or poor transient response, especially under 500-mA load steps.

How does the EN pin function on LP38693SDX-ADJ, and what are its voltage thresholds?

The EN pin on LP38693SDX-ADJ enables or disables the output: logic-high (>1.8 V at VIN=4 V, >3 V at VIN=6 V) turns ON the regulator; logic-low (<0.4 V) forces OFF state with ~1-µA quiescent current. No internal pullup/pulldown exists, so EN must be actively driven or tied to IN if unused. LP38693SDX-ADJ's EN behavior is explicitly documented in Section 7.3.1 of its datasheet.

What is the dropout voltage specification for LP38693SDX-ADJ at different output voltages and load currents?

At VOUT = 5 V, LP38693SDX-ADJ exhibits 250 mV typical dropout at 500 mA and 100 mV at 100 mA. At VOUT = 3.3 V, dropout is 330 mV (500 mA) and 65 mV (100 mA); at VOUT = 2.5 V, it is 430 mV (500 mA) and 80 mV (100 mA). All values increase across the full –40°C to +125°C range, with max 725 mV at 500 mA and 125°C.

Can LP38693SDX-ADJ be used with tantalum or aluminum electrolytic output capacitors?

No - LP38693SDX-ADJ is optimized for ultra-low-ESR ceramic capacitors (5–500 mΩ). Tantalum and aluminum electrolytics typically exceed 500 mΩ ESR and lack the necessary phase margin, risking instability and oscillation. The datasheet explicitly specifies ceramic-only stability and warns against alternatives in Section 8.2.2.4.

What thermal protection features does LP38693SDX-ADJ include, and how do they behave?

LP38693SDX-ADJ includes thermal shutdown that activates at ~160°C junction temperature and releases at ~150°C (10°C hysteresis). It cycles ON/OFF under sustained overload to limit average power dissipation. This feature is not a substitute for proper heatsinking: continuous cycling degrades reliability. The LP38693SDX-ADJ thermal metrics (RθJA = 68.5°C/W for SOT-223) are validated per JEDEC JESD51-7.