Texas Instruments LP38503TS-ADJ/NOPB

Overview

LP38503TS-ADJ/NOPB from Texas Instruments is an adjustable 3-A ultra-low-dropout linear regulator using a PMOS pass transistor, operating from 2.7 V to 5.5 V input and delivering 0.6 V to 5 V output with ±1.5% V_ADJ accuracy (A grade), 420 mV dropout at 3 A, and stable operation with any capacitor type including 10-µF ceramic. It serves as a primary power stage for FPGA core supplies in embedded computing systems.

For engineers reviewing the LP38503TS-ADJ/NOPB datasheet, LP38503TS-ADJ/NOPB pinout, LP38503TS-ADJ/NOPB application, or LP38503TS-ADJ/NOPB equivalent, key selection criteria include dropout voltage at full load, thermal performance in TO-263 packages, FlexCap stability with low-ESR ceramics, ground current behavior under 3-A load, and absence of enable functionality compared to LP38501 variants.

Technical Context

The LP38503TS-ADJ/NOPB implements a CMOS-based LDO architecture with a PMOS pass element, enabling ultra-low dropout and minimal ground current variation across load. Its FlexCap compensation eliminates ESR dependency, supporting stable regulation with ceramic, tantalum, or aluminum electrolytic output capacitors without external compensation networks.

Unlike the LP38501-ADJ, the LP38503TS-ADJ/NOPB omits the ENABLE pin and internal enable logic-its operation is always active when input voltage is applied. Thermal shutdown activates at 170°C with 10°C hysteresis, and short-circuit protection limits peak output current to 6 A while maintaining safe junction temperatures under sustained overload.

Key Specifications

Pinout & Package

LP38503TS-ADJ/NOPB uses a 5-pin TO-263 (NDQ) package with 10.16 mm × 9.85 mm body size and exposed thermal pad (DAP) electrically connected to GND. The DAP must be soldered to ≥4 cm² of inner-layer or bottom-side copper for thermal performance; it is not a functional signal terminal but critical for heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP38503TS-ADJ/NOPB, TPL7407LPGEDR lacks adjustability and current capability for core rails, while TPS7A8300RGRT trades FlexCap flexibility for lower noise-making LP38503TS-ADJ/NOPB the optimal choice for cost-sensitive, multi-capacitor-type industrial FPGA/DSP supplies requiring 3-A output and ±1.5% accuracy.

Availability

LP38503TS-ADJ/NOPB is available at Aetrix Electronics and suitable for FPGA core power supplies, DSP I/O regulation, ASIC voltage management, SMPS post-regulation, and industrial embedded computing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LP38503TS-ADJ/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, designing and manufacturing analog ICs, embedded processors, and high-reliability power management solutions since 1930.

The LP38503TS-ADJ/NOPB belongs to TI's FlexCap LDO family, engineered specifically for high-current, low-noise, capacitor-flexible power delivery in space-constrained industrial and computing applications where thermal robustness and load transient immunity are critical.

FAQ

What is the maximum continuous output current specification for LP38503TS-ADJ/NOPB?

The LP38503TS-ADJ/NOPB is specified for an ensured continuous output current of 3 A under recommended operating conditions. This rating assumes proper PCB thermal design-including ≥4 cm² of 2-oz copper connected to the DAP-and ambient temperature ≤85°C. At higher ambient temperatures or reduced copper area, derating per R_θJA = 33.3°C/W is required to maintain junction temperature below 125°C.

Does LP38503TS-ADJ/NOPB include an enable (EN) pin like the LP38501-ADJ?

No, LP38503TS-ADJ/NOPB does not include an enable pin. Unlike the LP38501-ADJ, which features an EN input for active control of output regulation, the LP38503TS-ADJ/NOPB operates continuously whenever valid input voltage is applied. Pin 1 on the TO-263 package is designated N/C (no connect) and must remain unconnected or used solely for routing.

What output capacitor types are supported by LP38503TS-ADJ/NOPB according to its FlexCap architecture?

LP38503TS-ADJ/NOPB supports ceramic, tantalum, and aluminum electrolytic output capacitors without stability restrictions-enabled by its FlexCap compensation architecture. Minimum 10-µF capacitance is required, and X5R/X7R dielectrics are recommended for ceramics. Unlike conventional LDOs, it imposes no ESR minimum or maximum, allowing use of ultra-low-ESR multilayer ceramics down to a few milliohms.

What is the dropout voltage of LP38503TS-ADJ/NOPB at full 3-A load, and how does it impact efficiency?

LP38503TS-ADJ/NOPB exhibits a typical dropout voltage of 420 mV at 3-A load. At 1.8-V output, this allows operation from a 3.3-V input rail with 92.5% theoretical efficiency (1.8 V / 2.22 V). Power dissipation is calculated as 3 A × 0.42 V = 1.26 W-requiring appropriate PCB copper area to maintain junction temperature within –40°C to +125°C limits.

How does the thermal shutdown mechanism operate in LP38503TS-ADJ/NOPB?

LP38503TS-ADJ/NOPB activates thermal shutdown at a junction temperature of 170°C, with 10°C hysteresis-meaning regulation resumes only after junction temperature falls below 160°C. During sustained overload or inadequate heatsinking, this results in cyclic on/off behavior. The DAP thermal pad must be soldered to a large copper plane to ensure R_θJB ≤ 16.9°C/W and prevent premature shutdown under 3-A load at elevated ambient temperatures.