Texas Instruments LP38842SX-1.5/NOPB

Overview

LP38842SX-1.5/NOPB from Texas Instruments is a 1.5A ultra-low-dropout linear regulator with fixed 1.5V output, N-MOS pass transistor architecture, and dual-rail operation (VIN + VBIAS). It delivers 1.5% initial output accuracy, 115mV typical dropout at 1.5A, and stable regulation with ≥22µF ceramic output capacitors. It is used in FPGA core power supplies and SMPS post-regulation where input-to-output differential is constrained.

For engineers reviewing the LP38842SX-1.5/NOPB datasheet, LP38842SX-1.5/NOPB pinout, LP38842SX-1.5/NOPB application, or LP38842SX-1.5/NOPB equivalent, key selection criteria include bias rail dependency (4.5–5.5V), thermal resistance of DDPAK/TO-263 package (35°C/W on 1-in² copper), shutdown threshold (0.7V typ), and ceramic capacitor stability requirements.

Technical Context

The LP38842SX-1.5/NOPB employs a CMOS-based N-MOS pass transistor driven by an independent VBIAS rail, enabling operation with VIN as low as VOUT + 115mV. Its control loop is optimized for stability with low-ESR ceramic output capacitors (≥22µF) and includes internal overtemperature and overcurrent protection.

It features separate ground return paths for power and analog circuitry, with both Pin 3 and the exposed tab at GND potential. The S/D pin provides active-low shutdown with 30nA typical quiescent current in off-state, and the device supports fast transient response critical for digital load switching.

Key Specifications

Pinout & Package

LP38842SX-1.5/NOPB is housed in a 5-pin DDPAK/TO-263 (KTT) package with exposed thermal pad soldered to PCB copper plane for heat dissipation. Thermal resistance θ_J-A is 35°C/W when mounted on ≥1 in² of 1-oz copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP38842SX-1.5/NOPB, TPS7A8300RGRT offers lower dropout and simpler biasing but lacks VBIAS-driven ultra-low-VIN capability; LT3080IMSE#PBF provides adjustability at the cost of current rating, dropout, and fixed-output precision.

Availability

LP38842SX-1.5/NOPB is available at Aetrix Electronics and suitable for FPGA core power supplies, SMPS post-regulation, and server I/O voltage rails requiring stable component supply, long-term lifecycle support, and RoHS-exempt packaging for industrial environments.

Supply support for LP38842SX-1.5/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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs with broad industrial, automotive, and communications reach.

The LP38842 series belongs to TI's ultra-low-dropout linear regulator product line, designed specifically for high-current, low-headroom applications in digital systems where ceramic capacitor compatibility and fast transient response are mandatory.

FAQ

What is the minimum input voltage required for LP38842SX-1.5/NOPB to regulate 1.5V output?

The LP38842SX-1.5/NOPB requires a minimum input voltage of VOUT + VDO = 1.5V + 115mV = 1.615V at 1.5A load under typical conditions. At lighter loads, dropout decreases-e.g., 75mV at 500mA-so VIN may be reduced accordingly. However, VBIAS must remain within 4.5–5.5V regardless of VIN level.

Can LP38842SX-1.5/NOPB operate without the VBIAS supply?

No. LP38842SX-1.5/NOPB requires a dedicated 4.5–5.5V VBIAS supply to power its internal gate driver and control circuitry. Omitting VBIAS prevents proper N-MOS pass transistor operation and results in no regulated output. The VBIAS pin must be decoupled with a 0.1µF ceramic capacitor placed near the pin.

What ceramic capacitor dielectrics are approved for use with LP38842SX-1.5/NOPB?

Only X5R and X7R ceramic dielectrics are approved for the output capacitor of LP38842SX-1.5/NOPB. Z5U and Y5V types are prohibited due to severe capacitance loss over temperature and DC bias-potentially falling below the 22µF minimum and destabilizing regulation. Input capacitor must also be X5R or X7R, ≥10µF.

How does the thermal performance of LP38842SX-1.5/NOPB compare between TO-220 and DDPAK packages?

LP38842SX-1.5/NOPB in DDPAK/TO-263 (KTT) achieves θ_J-A = 35°C/W on 1 in² of 1-oz copper, versus 65°C/W for TO-220 without heatsink. This 46% lower thermal resistance allows 1.5A continuous operation at higher ambient temperatures. The DDPAK's exposed tab must be soldered directly to the PCB ground plane for effective heat transfer.

Is LP38842SX-1.5/NOPB compatible with tantalum output capacitors?

Yes-LP38842SX-1.5/NOPB is stable with 4.7µF solid tantalum output capacitors, which provide faster transient settling than ceramics. However, tantalum capacitors exhibit higher ESR and poorer high-frequency noise filtering. For best noise performance and reliability, X5R/X7R ceramics ≥22µF are preferred per TI's design recommendations.