Texas Instruments LP38690SDX-3.3

Overview

LP38690SDX-3.3 from Texas Instruments is a 3.3 V, 1-A low-dropout CMOS linear regulator in a 6-pin WSON package, featuring 2.5% output voltage accuracy at 25°C, 650 mV dropout at 1 A (V_OUT = 3.3 V), and stable operation with only 1-µF ceramic output capacitance. It delivers precision regulation for battery-powered portable instrumentation and notebook computer core logic rails where low quiescent current (55 µA typical) and thermal robustness are critical.

For engineers reviewing the LP38690SDX-3.3 datasheet, LP38690SDX-3.3 pinout, LP38690SDX-3.3 application, or LP38690SDX-3.3 equivalent, this page provides verified technical context, validated WSON-6 pin functions, real-world load/line regulation performance, thermal derating guidance, and two confirmed alternative regulators for 3.3 V LDO selection in space-constrained industrial and portable designs.

Technical Context

The LP38690SDX-3.3 uses a PMOS pass transistor architecture enabling ultra-low ground pin current (55 µA typical at full 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 operating junction range.

It integrates foldback current limiting (1500 mA at VIN–VOUT < 4 V; 450 mA at VIN–VOUT > 5 V) and thermal shutdown activation at 160°C with 10°C hysteresis. Unlike the LP38692, it lacks an enable pin - operation is always active when VIN ≥ 2.7 V and VIN ≥ (VOUT + V_DO).

Key Specifications

Pinout & Package

LP38690SDX-3.3 is housed in a 3.0 mm × 3.0 mm, 0.8-mm height, 6-bump WSON package (NGG) with exposed thermal pad (DAP) on bottom. The DAP must be soldered to a PCB copper plane for effective heat dissipation and electrical grounding.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3.3 V, 1-A LDO applications.

Compared with TSS721AIDR and MCP1703T-3302E/MB, LP38690SDX-3.3 uniquely balances 1-A capability, 650-mV dropout, 1-µF ceramic stability, and 55-µA quiescent current in a 3×3 mm WSON - making it optimal for thermally dense, battery-sensitive 3.3 V systems where both performance and footprint are constrained.

Availability

LP38690SDX-3.3 is available at Aetrix Electronics and suitable for hard disk drives, notebook computers, and battery-powered portable instrumentation requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.

Supply support for LP38690SDX-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 leader designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and consumer markets.

The LP38690 series belongs to TI's precision low-dropout linear regulator product line, engineered specifically for portable and battery-operated systems demanding high accuracy, low noise, and ceramic-capacitor compatibility in minimal footprints.

FAQ

What is the dropout voltage specification for LP38690SDX-3.3 at full 1-A load?

The LP38690SDX-3.3 has a dropout voltage of 650 mV at 1 A load and 3.3 V output, measured at 25°C. At –40°C to +125°C, the maximum dropout rises to 1000 mV. This means the device maintains regulation as long as input voltage stays ≥4.3 V under full load - critical for brownout resilience in Li-ion-powered devices. The value is confirmed in Section 6.5, Electrical Characteristics, of the SNVS322M datasheet.

Does LP38690SDX-3.3 include an enable (EN) pin?

No, LP38690SDX-3.3 does not have an enable pin. It is a permanently enabled regulator - unlike the LP38692 variant, which includes EN functionality. Operation begins automatically when input voltage reaches ≥2.7 V and exceeds the dropout threshold. This simplifies design for always-on rails but removes software-controlled power gating capability. The pinout diagram for LP38690 WSON confirms absence of EN (Pin 3 is N/C).

What output capacitor is required for stable operation of LP38690SDX-3.3?

LP38690SDX-3.3 is stable with a minimum 1-µF ceramic capacitor (X5R or X7R dielectric) at the output. This is explicitly specified in the "Typical Applications" section and validated across ESR range 5–500 mΩ. Larger values improve transient response but are not required for stability. Avoid using electrolytic or polymer capacitors unless ESR falls within the validated window - ceramic MLCCs provide optimal size, reliability, and noise performance.

How is thermal performance managed in the WSON package of LP38690SDX-3.3?

Thermal performance relies on soldering the exposed DAP (pinless thermal pad) to a ≥100 mm² PCB copper plane. With proper layout, junction-to-board thermal resistance is 24.9°C/W, allowing full 1-A operation up to 85°C ambient. Without DAP connection, R_θJA degrades to 50.6°C/W, limiting safe continuous current to ~600 mA at 25°C ambient. TI Application Report AN-1187 provides layout guidelines for WSON mounting and thermal vias.

Is LP38690SDX-3.3 compatible with reverse-voltage conditions?

LP38690SDX-3.3 tolerates reverse voltage up to 500 mV (typical) via its intrinsic PFET body diode, but sustained reverse current >1 A continuous or >5 A peak risks damage. During abrupt VIN removal, output capacitor discharge through the body diode is acceptable for ≤1000 µF caps. For dual-supply systems or negative transients, TI recommends adding a Schottky clamp diode from VOUT to GND - a design requirement noted in Section 8.1.1 of the datasheet.