Texas Instruments LP38693QSD-3.3/NOPB

Overview

LP38693QSD-3.3/NOPB from Texas Instruments is a 500-mA, 3.3-V fixed-output CMOS low-dropout linear regulator in a 6-pin WSON package with enable (EN) and remote sense (SNS) pins. It delivers 2% output accuracy at 25°C, 250 mV dropout at 500 mA (V_OUT = 5 V), and stable operation with only 1-µF ceramic output capacitance - used in notebook computers and battery-powered instrumentation for clean, compact power delivery.

For engineers reviewing the LP38693QSD-3.3/NOPB datasheet, LP38693QSD-3.3/NOPB pinout, LP38693QSD-3.3/NOPB application, or LP38693QSD-3.3/NOPB equivalent, key selection criteria include its 2.7–10 V input range, 1-µA shutdown quiescent current, thermal overload protection, foldback current limiting, and WSON-6 package with exposed thermal pad for high-temperature operation up to 125°C.

Technical Context

The LP38693QSD-3.3/NOPB uses a PMOS pass transistor enabling ultra-low ground pin current (55 µA typical at full load) independent of load, input voltage, or temperature. Its precision trimmed bandgap reference ensures 2% output tolerance across –40°C to 125°C, and its internal foldback current limit responds dynamically to VIN–VOUT differential: limiting to ~350 mA when ΔV > 5 V and ~850 mA when ΔV < 4 V.

Unlike the LP38691, the LP38693QSD-3.3/NOPB integrates an active-enable logic circuit with no internal pull-up/down on EN, requiring external termination. The SNS pin enables remote voltage sensing for load-side regulation correction - functional only in WSON packages and must be tied directly to OUT unless used for true remote sensing.

Key Specifications

Pinout & Package

The LP38693QSD-3.3/NOPB is housed in a 3.0 mm × 3.0 mm, 6-pin WSON package with an exposed thermal pad (DAP) on the bottom for enhanced heat dissipation. The DAP must be soldered to a PCB copper plane per TI's AN-1187 guidelines to achieve specified R_θJB = 24.9°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLS850F3TAV50 and TPS7A2033PDQNR, the LP38693QSD-3.3/NOPB uniquely combines remote sensing, foldback current limiting, and 1-µA shutdown in a cost-optimized industrial-grade WSON package - making it optimal for portable instrumentation requiring load-point regulation and thermal resilience without automotive qualification overhead.

Availability

LP38693QSD-3.3/NOPB is available at Aetrix Electronics and suitable for notebook computers, battery-powered medical devices, and portable test equipment requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LP38693QSD-3.3/NOPB 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 LP38693QSD-3.3/NOPB belongs to TI's LP3869x family of CMOS LDOs engineered for portable, battery-powered digital systems demanding fast start-up, tight output tolerance, and ceramic-capacitor stability - targeting space- and power-constrained applications from consumer portables to industrial instrumentation.

FAQ

What is the minimum input voltage required for LP38693QSD-3.3/NOPB to regulate 3.3 V output?

The LP38693QSD-3.3/NOPB requires VIN ≥ (VOUT + VDO) or 2.7 V, whichever is higher. With a typical dropout of 330 mV at 500 mA, minimum VIN is 3.63 V under full load. At light loads, dropout drops significantly - e.g., ~110 mV at 100 mA - allowing regulation down to ~3.41 V. Below 2.7 V, internal circuitry is nonfunctional.

Can the SNS pin of LP38693QSD-3.3/NOPB be left unconnected?

No. Per TI's datasheet, the SNS pin on LP38693QSD-3.3/NOPB must be tied directly to the OUT pin if remote sensing is not used. Leaving it floating violates the recommended operating conditions and may cause instability or output inaccuracy. When used for remote sensing, SNS connects to the load-side VOUT node to compensate for trace resistance.

Does LP38693QSD-3.3/NOPB support reverse voltage protection?

The LP38693QSD-3.3/NOPB does not integrate reverse voltage protection. During reverse voltage (VOUT > VIN), current flows through the PMOS parasitic body diode - limited to <1 A continuous or <5 A peak. For robust protection, TI recommends adding an external Schottky diode from OUT to GND or using a dedicated reverse-protection IC upstream of LP38693QSD-3.3/NOPB.

How does the foldback current limiting behave on LP38693QSD-3.3/NOPB during enable cycling?

Per TI's caution note, foldback limiting is functional only on the first EN high transition after VIN application. Subsequent toggles of EN do not re-engage foldback - potentially causing higher inrush current. To ensure consistent current limiting, tie EN directly to IN if enable control is unnecessary, or use a power-good sequencer that asserts EN only once per power cycle.

Is the exposed thermal pad (DAP) on LP38693QSD-3.3/NOPB electrically connected to GND?

No. The DAP on LP38693QSD-3.3/NOPB is electrically isolated and serves only as a thermal conduction path. It must be soldered to a PCB copper pour for thermal performance but must not be connected to any electrical net - including GND - unless explicitly designed as a thermal-only pad per TI's WSON mounting guidelines (AN-1187).