Texas Instruments LP38841SX-0.8/NOPB

Overview

LP38841SX-0.8/NOPB from Texas Instruments is a 0.8A ultra-low-dropout linear regulator with 0.8V fixed output, 75mV typical dropout at full load, ±1.5% initial output accuracy, and stable operation with ceramic output capacitors. It employs an N-MOS pass transistor with separate VBIAS rail (4.5–5.5V) to enable regulation from inputs as low as VOUT + 75mV, making it suitable for post-regulation of SMPS outputs in FPGA core supplies.

For engineers reviewing the LP38841SX-0.8/NOPB datasheet, LP38841SX-0.8/NOPB pinout, LP38841SX-0.8/NOPB application, or LP38841SX-0.8/NOPB equivalent, this device delivers precise low-voltage regulation with fast transient response, 30nA shutdown current, and thermal/overcurrent protection - critical for high-efficiency embedded power domains requiring tight voltage tolerance and minimal quiescent loss.

Technical Context

The LP38841SX-0.8/NOPB uses a CMOS-based architecture with an N-channel MOSFET pass element driven by an external 4.5–5.5V bias supply, decoupling gate drive from the main input path. This enables ultra-low dropout while maintaining stability with ≥22µF ceramic output capacitance.

Its control loop is optimized for wide bandwidth and minimal external compensation: input voltage ripple rejection reaches 80dB at 120Hz (VIN), and output noise is 150µV_rms (10Hz–100kHz). Protection includes thermal shutdown, current limiting (2.6A short-circuit), and under-voltage lockout on VBIAS.

Key Specifications

Pinout & Package

LP38841SX-0.8/NOPB is packaged in a 5-pin DDPAK/TO-263 (KTT) thermally enhanced surface-mount package with exposed thermal pad. Pin 3 (GND) and the metal tab are internally connected to ground, requiring direct PCB copper connection for optimal thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A8300RGRT and MCP1826T-0802E/DB, LP38841SX-0.8/NOPB uniquely combines 75mV dropout with a dedicated BIAS rail for sub-1V input operation and ±1.5% accuracy - making it the only option among the three capable of stable 0.8V regulation from 0.875V sources in thermally constrained layouts.

Availability

LP38841SX-0.8/NOPB is available at Aetrix Electronics and suitable for FPGA core supplies, ASIC power domains, and SMPS post-regulation applications requiring stable component supply, long-term lifecycle support, and RoHS-exempt lead finish for high-reliability soldering.

Supply support for LP38841SX-0.8/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 leader specializing in analog, embedded processing, and power management technologies, with over 50 years of innovation in high-reliability power solutions.

The LP38841 series belongs to TI's ultra-low-dropout linear regulator product line, designed specifically for high-current, low-voltage post-regulation in digital systems where precision, thermal efficiency, and ceramic-capacitor compatibility are mandatory.

FAQ

What is the minimum input voltage required for LP38841SX-0.8/NOPB to maintain regulation?

The LP38841SX-0.8/NOPB requires a minimum input voltage of VOUT + VDO = 0.8V + 75mV = 0.875V at 0.8A load under typical conditions. However, the separate VBIAS rail (4.5–5.5V) must also be present to drive the N-MOS pass transistor - the IN pin itself can operate down to this ultra-low differential, but VBIAS remains mandatory for functionality. This dual-rail architecture enables operation unreachable by single-supply LDOs.

Can LP38841SX-0.8/NOPB be used with tantalum output capacitors?

Yes, LP38841SX-0.8/NOPB supports tantalum output capacitors with a minimum value of 4.7µF, as specified in the Application Hints section. However, ceramic capacitors (≥22µF, X5R/X7R) are preferred for lower ESR, higher reliability, and superior high-frequency noise filtering. Tantalum use requires careful derating for temperature and voltage to avoid failure modes not present with ceramics.

What is the thermal performance of LP38841SX-0.8/NOPB in its DDPAK/TO-263 package?

LP38841SX-0.8/NOPB in the DDPAK/TO-263 (KTT) package has a junction-to-ambient thermal resistance (θ_J-A) of 35°C/W when mounted on a 1 in² copper plane. At maximum 0.8A load and 0.075V dropout, power dissipation is 60mW - well within safe operating limits even at 85°C ambient. No external heatsink is required under these conditions.

Does LP38841SX-0.8/NOPB require an input capacitor, and what type is recommended?

Yes, LP38841SX-0.8/NOPB requires a minimum 10µF ceramic input capacitor (X5R or X7R dielectric) located within 1cm of the IN pin and returned to clean analog ground. Tantalum capacitors are explicitly not recommended for the input due to insufficient high-frequency impedance and potential instability. The capacitor stabilizes the input source impedance and improves transient response.

How does the shutdown function operate on LP38841SX-0.8/NOPB?

The S/D pin on LP38841SX-0.8/NOPB is an active-low shutdown control. Pulling it below 0.7V turns off the output; pulling it above 1.3V enables regulation. When unused, it must be tied to VBIAS. The device draws only 30nA in shutdown, and turn-off delay is 20µs. A pull-up resistor (10–100kΩ) is required unless driven by a rail-to-rail CMOS output.