Texas Instruments LP38841S-1.5/NOPB

Overview

LP38841S-1.5/NOPB from Texas Instruments is a 1.5V, 0.8A ultra-low-dropout linear regulator using an N-MOS pass transistor with separate bias rail (VBIAS), delivering 75mV dropout at full load and stable operation with ceramic output capacitors ≥22µF. It targets core voltage regulation in DSPs, FPGAs, and SMPS post-regulation where input-to-output differential is minimal.

For engineers reviewing the LP38841S-1.5/NOPB datasheet, LP38841S-1.5/NOPB pinout, LP38841S-1.5/NOPB application, or LP38841S-1.5/NOPB equivalent, key selection criteria include its dual-supply architecture (VIN + VBIAS), 1.5% initial output accuracy, −40°C to +125°C junction temperature range, and DDPAK/TO-263 package thermal performance (θ_J-A = 35°C/W with 1 in² copper).

Technical Context

The LP38841S-1.5/NOPB employs a CMOS-based control circuit with external VBIAS (4.5–5.5V) to drive the N-MOS pass element, enabling operation with VIN as low as VOUT + 75mV. Its loop stability relies on minimum 22µF ceramic C_OUT or 4.7µF tantalum, leveraging ESR-dependent phase margin for bandwidth control.

It integrates over-temperature and over-current protection, features 30nA shutdown current when S/D is pulled low, and maintains 0.1%/A load regulation. The device requires dedicated ground routing for both GND pin and exposed tab, which are internally tied and must be connected to system ground via PCB copper.

Key Specifications

Pinout & Package

LP38841S-1.5/NOPB is housed in a 5-pin DDPAK/TO-263 (KTT) package with exposed thermal pad (GND-connected). Pin 1 is INPUT; Pin 2 is GND; Pin 3 is OUTPUT; Pin 4 is BIAS; Pin 5 is SHUTDOWN. The metal tab is electrically connected to GND and must be soldered to a ≥1 in² copper pour for thermal management.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A8300RGRT, LP38841S-1.5/NOPB trades higher quiescent current for greater VIN flexibility via VBIAS, while TPL7407LDR serves entirely different functional roles-neither is pin-compatible nor drop-in, and LP38841S-1.5/NOPB remains uniquely suited for high-current, ultra-low-dropout dual-supply applications.

Availability

LP38841S-1.5/NOPB is available at Aetrix Electronics and suitable for ASIC power supplies in desktops and graphics cards, server core and I/O supplies, DSP and FPGA power supplies, and SMPS post-regulator applications requiring stable component supply, long-lifecycle support, and RoHS-exempt compliance.

Supply support for LP38841S-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 connectivity technologies for industrial, automotive, and communications markets.

The LP38841 series belongs to TI's ultra-low-dropout linear regulator product line, engineered specifically for high-current, low-noise core voltage regulation in digital systems where input-to-output differential is severely constrained and ceramic capacitor stability is mandatory.

FAQ

What is the minimum input voltage required for LP38841S-1.5/NOPB to maintain regulation?

The LP38841S-1.5/NOPB requires a minimum input-to-output differential of 75mV at 0.8A load, meaning VIN must be ≥1.575V to sustain 1.5V output regulation. This value is specified at TJ = 25°C and may increase slightly at higher temperatures or full load. The separate VBIAS rail (4.5–5.5V) enables this ultra-low dropout behavior by independently powering the control circuitry.

Can LP38841S-1.5/NOPB operate without an external bias supply?

No-LP38841S-1.5/NOPB requires an external 4.5–5.5V bias voltage applied to the BIAS pin to power its internal CMOS control circuitry and drive the N-MOS pass transistor gate. Omitting VBIAS will prevent regulation. If only one supply is available, a simple resistive divider or LDO from VIN is insufficient; a dedicated low-noise 5V rail is mandatory for proper operation of LP38841S-1.5/NOPB.

What output capacitor is required for stable operation of LP38841S-1.5/NOPB?

LP38841S-1.5/NOPB requires a minimum 22µF X7R or X5R ceramic output capacitor placed within 1 cm of the OUTPUT pin and returned to clean analog ground. Tantalum capacitors are acceptable at 4.7µF minimum but introduce higher ESR and slower transient response. Z5U or Y5V ceramics are prohibited due to severe capacitance loss with temperature and DC bias, risking instability in LP38841S-1.5/NOPB operation.

How does the shutdown function work on LP38841S-1.5/NOPB?

The SHUTDOWN pin on LP38841S-1.5/NOPB is active-low: pulling it ≤0.3V disables the output and reduces quiescent current to 30nA typical. When unused, it must be tied to VBIAS. If driven by an open-drain source (e.g., microcontroller GPIO), a 10–100kΩ pull-up resistor to VBIAS is required. The turn-off delay is 20µs, and turn-on delay is 15µs, enabling fast power sequencing in LP38841S-1.5/NOPB-based systems.

Is LP38841S-1.5/NOPB compatible with lead-free reflow processes?

Yes-LP38841S-1.5/NOPB is RoHS-exempt but qualified for lead-free reflow per JEDEC Level-3 (245°C peak, 168-hour floor life). Its DDPAK/TO-263 (KTT) package uses Sn (tin) lead finish and is rated for standard Pb-free soldering profiles. Thermal validation confirms reliability under IPC/JEDEC J-STD-020 conditions, making LP38841S-1.5/NOPB suitable for modern high-volume manufacturing environments.