Texas Instruments LP38841SX-1.2/NOPB

Overview

LP38841SX-1.2/NOPB from Texas Instruments is a 0.8A ultra-low-dropout linear regulator with fixed 1.2V output, CMOS N-MOS pass transistor architecture, 75mV typical dropout at full load, ±1.5% initial output accuracy, and stable operation with ceramic output capacitors ≥22µF. It is used in FPGA core power, DSP post-regulation, and server I/O supplies where low VIN–VOUT headroom and fast transient response are critical.

For engineers reviewing the LP38841SX-1.2/NOPB datasheet, LP38841SX-1.2/NOPB pinout, LP38841SX-1.2/NOPB application, or LP38841SX-1.2/NOPB equivalent, key selection criteria include bias rail dependency (4.5–5.5V VBIAS), shutdown current (30nA typ), thermal resistance (θJA = 35°C/W on 1-in² copper), PSRR performance (80dB @120Hz on VIN), and DDPAK/TO-263 package compatibility with high-current PCB heatsinking.

Technical Context

The LP38841SX-1.2/NOPB employs a dual-rail architecture: VIN supplies load current while VBIAS (4.5–5.5V) powers internal circuitry and drives the N-MOS gate, enabling operation with input voltages as low as VOUT + 75mV. Its CMOS design delivers 30mA quiescent current at full load and only 30nA in shutdown-critical for battery-backed or always-on systems.

Stability is achieved via external capacitor selection: 22µF ceramic (X7R/X5R) or 4.7µF tantalum on VOUT, 10µF ceramic on VIN, and 0.1µF on VBIAS. The device integrates overtemperature and overcurrent protection, with thermal shutdown activating above 150°C junction temperature and short-circuit current limited to 2.6A.

Key Specifications

Pinout & Package

LP38841SX-1.2/NOPB is housed in a 5-pin DDPAK/TO-263 (KTT) package with exposed thermal pad (pin 3 = GND). The tab is electrically connected to GND and must be soldered to ≥1 in² copper for 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 TPS7A4700RGWR and TPS74901KTTR, the LP38841SX-1.2/NOPB uniquely balances 0.8A delivery, 75mV dropout, and dual-rail efficiency-making it optimal for space-constrained, high-density 1.2V core supplies where VBIAS availability is acceptable.

Availability

LP38841SX-1.2/NOPB is available at Aetrix Electronics and suitable for FPGA power supplies, server I/O regulation, and DSP core voltage applications requiring stable component supply, long-term lifecycle support, and RoHS-exempt compliance for industrial deployment.

Supply support for LP38841SX-1.2/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 ICs, with decades of expertise in high-reliability linear regulators and power delivery solutions.

The LP38841 family was designed specifically for high-current, ultra-low-dropout point-of-load regulation in computing, networking, and industrial systems-emphasizing thermal robustness, ceramic capacitor compatibility, and fast transient immunity.

FAQ

What is the minimum input voltage required for LP38841SX-1.2/NOPB to regulate 1.2V output?

The LP38841SX-1.2/NOPB requires a minimum input voltage of VOUT + VDO = 1.2V + 75mV = 1.275V at 0.8A load. This ultra-low dropout enables operation from tightly regulated intermediate rails. Note that VBIAS must be independently supplied at 4.5–5.5V regardless of VIN level-ensuring gate drive remains functional even when VIN approaches VOUT.

Can LP38841SX-1.2/NOPB operate without an external VBIAS supply?

No. The LP38841SX-1.2/NOPB requires an external 4.5–5.5V VBIAS rail to power internal circuitry and drive the N-MOS gate. Without VBIAS, the device cannot regulate-even if VIN is present. Under-voltage lockout disables output if VBIAS falls below ~4V, preventing unstable operation.

What output capacitor types and values are validated for LP38841SX-1.2/NOPB stability?

The LP38841SX-1.2/NOPB is stable with either 22µF X7R or X5R ceramic capacitors (minimum), or 4.7µF solid tantalum capacitors. Z5U and Y5V ceramics are prohibited due to severe capacitance loss with temperature/voltage. Ceramic placement must be ≤1 cm from OUTPUT pin and returned to clean analog ground.

How does the shutdown function work on LP38841SX-1.2/NOPB?

The SHUTDOWN pin is active-low: pulling it ≤0.3V disables the output and reduces quiescent current to 0.06µA from VIN and 0.03µA from VBIAS. If unused, it must be tied to VBIAS. A pull-up resistor (10–100kΩ) is required when driven by open-drain sources to ensure reliable turn-on.

What thermal performance can be expected from LP38841SX-1.2/NOPB in a standard PCB layout?

When mounted on a 1 in² (2.54 cm²) copper plane (1 oz), the LP38841SX-1.2/NOPB achieves θJA = 35°C/W. At 25°C ambient and 0.8A load with 1.275V input, power dissipation is ~60mW-resulting in ~2.1°C junction rise. Full 1.5W dissipation is possible before reaching 125°C junction limit under same conditions.