Texas Instruments LP38690DTX-3.3

Overview

LP38690DTX-3.3 from Texas Instruments is a 3.3 V, 1-A low-dropout CMOS linear regulator in TO-252 (DPAK) package, featuring 2.5% output voltage accuracy at 25°C, 650 mV dropout at 1 A (VOUT = 3.3 V), and stable operation with only 1-µF ceramic output capacitance. It delivers precision regulation for battery-powered digital systems such as portable instrumentation and notebook computers.

For engineers reviewing the LP38690DTX-3.3 datasheet, LP38690DTX-3.3 pinout, LP38690DTX-3.3 application, or LP38690DTX-3.3 equivalent, key selection criteria include dropout voltage at full load, ground pin current under load, thermal shutdown threshold, stability with ultra-low-ESR capacitors, and compatibility with 2.7–10 V input rails.

Technical Context

The LP38690DTX-3.3 uses a PMOS pass transistor to eliminate DC base drive current, enabling ground pin current of just 55 µA (typical) at full 1-A load - independent of input voltage or temperature. Its trimmed bandgap reference and internal feedback network ensure ±2.5% output tolerance over –40°C to 125°C.

Unlike the LP38692 variant, the LP38690DTX-3.3 lacks an enable (EN) pin and sense (SNS) pin - confirmed by its 3-pin TO-252 configuration and functional block diagram. It relies on direct IN/OUT/GND connection and does not support remote sensing or external control sequencing.

Key Specifications

Pinout & Package

LP38690DTX-3.3 is housed in a 3-lead TO-252 (DPAK) package with exposed thermal pad (DAP) on the bottom surface. The package measures 6.58 mm × 6.10 mm and requires soldering the DAP to a large copper plane for optimal thermal performance (R_θJB = 29.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSS721AIDR and MCP1703T-3302E/MB, LP38690DTX-3.3 offers superior thermal robustness (125°C operation), lower ground current, and tighter output tolerance - making it the preferred choice for high-reliability, 1-A portable and industrial applications requiring long-term stability.

Availability

LP38690DTX-3.3 is available at Aetrix Electronics and suitable for hard disk drives, notebook computers, battery-powered devices, portable instrumentation, and other applications requiring stable component supply with guaranteed long-term manufacturability.

Supply support for LP38690DTX-3.3 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 headquartered in Dallas, Texas, designing and manufacturing analog and embedded processing chips for industrial, automotive, and personal electronics markets.

The LP38690DTX-3.3 belongs to TI's precision low-dropout linear regulator product line, engineered specifically for portable, battery-powered digital systems demanding accurate voltage, fast start-up, and ceramic-capacitor stability.

FAQ

What is the dropout voltage of LP38690DTX-3.3 at 1 A load?

The dropout voltage of LP38690DTX-3.3 is 650 mV at 1 A load and 3.3 V output, measured at 25°C. At –40°C to 125°C, it rises to a maximum of 1000 mV. This defines the minimum input voltage required for regulation: VIN ≥ 4.3 V at full load and room temperature, or VIN ≥ 4.3 V + derating margin at elevated temperatures.

Does LP38690DTX-3.3 have an enable (EN) pin?

No, LP38690DTX-3.3 does not include an enable pin. It is a three-terminal device (IN, OUT, GND) with no external control functionality. The LP38692 variant provides EN and SNS pins, but LP38690DTX-3.3 operates continuously when powered - making it suitable for always-on applications where simplicity and low quiescent current are priorities.

What output capacitor value is required for stable operation of LP38690DTX-3.3?

LP38690DTX-3.3 is stable with a minimum 1-µF ceramic output capacitor (X5R or X7R dielectric, 5–500 mΩ ESR). TI validates stability using 10-µF capacitors in characterization, but the 1-µF minimum is specified for production designs. Larger values improve transient response but are not required for loop stability.

Can LP38690DTX-3.3 be used with input voltages below 3.3 V?

No - LP38690DTX-3.3 cannot regulate when input voltage falls below the sum of its output voltage and dropout voltage. With a 3.3-V output and 650-mV typical dropout, VIN must remain ≥3.95 V at 1 A load and 25°C. Its absolute minimum input is 2.7 V, but regulation only begins when VIN ≥ (VOUT + VDO), so sub-3.3-V inputs yield unregulated or zero output.

What is the thermal resistance (R_θJA) of LP38690DTX-3.3 in its TO-252 package?

The junction-to-ambient thermal resistance (R_θJA) of LP38690DTX-3.3 in the TO-252 package is 50.5°C/W under standard JEDEC High-K test board conditions. Actual thermal performance depends heavily on PCB layout - soldering the exposed thermal pad (DAP) to ≥1 in² of 2-oz copper reduces R_θJA significantly and is mandatory for 1-A continuous operation at elevated ambient temperatures.