Texas Instruments LP38843SX-1.2/NOPB

Overview

LP38843SX-1.2/NOPB from Texas Instruments is a 3A ultra-low-dropout linear regulator with fixed 1.2V output, CMOS N-MOS pass transistor architecture, 210mV typical dropout at 3A, ±1.5% initial output accuracy, and stable operation with ceramic output capacitors ≥22µF. It powers FPGA core rails in server I/O modules where tight regulation and fast transient response are critical.

For engineers reviewing the LP38843SX-1.2/NOPB datasheet, LP38843SX-1.2/NOPB pinout, LP38843SX-1.2/NOPB application, or LP38843SX-1.2/NOPB equivalent, key selection factors include its dual-rail input (VIN + VBIAS), 30nA shutdown current, −40°C to +125°C junction temperature range, and DDPAK/TO-263 thermal performance with θ_J-A = 35°C/W on 1-in² copper.

Technical Context

The LP38843SX-1.2/NOPB uses an external 4.5–5.5V bias rail to drive the gate of its N-MOS power transistor, enabling ultra-low VIN operation (as low as VOUT + 210mV). Its CMOS control circuitry delivers 30mA typical quiescent current at full load and 30nA in shutdown-critical for always-on subsystems.

Stability is achieved via internal compensation optimized for ceramic output capacitors (≥22µF) or tantalum (≥4.7µF), with PSRR of 80dB at 120Hz on VIN and 58dB on VBIAS. Built-in overtemperature and overcurrent protection ensure robust operation in high-density power delivery networks.

Key Specifications

Pinout & Package

LP38843SX-1.2/NOPB is housed in a 5-pin DDPAK/TO-263 (KTT) package with exposed thermal pad soldered to PCB copper for heat dissipation. Pin 1 (INPUT) and Pin 5 (SHUTDOWN) are on one side; Pin 2 (BIAS), Pin 3 (GND), and Pin 4 (OUTPUT) align opposite. The metal tab is electrically connected to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPL7407LDR and TPS7A8300RGRT, LP38843SX-1.2/NOPB uniquely supports ultra-low input operation via dedicated VBIAS, making it irreplaceable in 1.4–1.5V input systems-where alternatives either lack current capacity or require higher minimum VIN.

Availability

LP38843SX-1.2/NOPB is available at Aetrix Electronics and suitable for server I/O supplies, FPGA core rails, ASIC power domains, and SMPS post-regulation requiring stable component supply across extended temperature and high-reliability production cycles.

Supply support for LP38843SX-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 power delivery solutions.

The LP38843 series was designed specifically for high-current, low-noise, ultra-low-dropout regulation in FPGA, ASIC, and DSP core power applications-emphasizing thermal efficiency, ceramic capacitor compatibility, and wide-junction-temperature operation.

FAQ

What is the minimum input voltage required for LP38843SX-1.2/NOPB to regulate 1.2V output?

The LP38843SX-1.2/NOPB requires a minimum input voltage of VOUT + VDO = 1.2V + 0.21V = 1.41V at 3A load, per its 210mV typical dropout specification. This ultra-low dropout is enabled by its separate VBIAS rail (4.5–5.5V), which drives the N-MOS pass transistor independently of VIN. Below 1.41V, regulation is not guaranteed.

Can LP38843SX-1.2/NOPB operate without the BIAS pin connected?

No. The LP38843SX-1.2/NOPB requires a 4.5–5.5V supply on the BIAS pin to power its internal CMOS control circuitry and drive the N-MOS gate. If left unconnected, the device will not regulate. If unused, BIAS must be tied to a valid 4.5–5.5V source-not left floating or grounded.

What output capacitor is required for stable operation of LP38843SX-1.2/NOPB?

LP38843SX-1.2/NOPB requires ≥22µF of X7R or X5R ceramic capacitance placed within 1cm of the OUTPUT pin and returned to clean analog ground. Tantalum capacitors are acceptable at ≥4.7µF but offer slower transient response. Z5U/Y5V ceramics are prohibited due to severe capacitance loss with temperature and bias voltage.

Does LP38843SX-1.2/NOPB include thermal protection?

Yes. LP38843SX-1.2/NOPB integrates thermal shutdown that activates when junction temperature exceeds +150°C. Once triggered, the output disables until the die cools sufficiently. This protection operates independently of external components and is documented in the Absolute Maximum Ratings table of the SNVS290C datasheet.

What is the shutdown current consumption of LP38843SX-1.2/NOPB?

The LP38843SX-1.2/NOPB draws 30nA typical current from VIN when the SHUTDOWN pin is pulled low (≤0.3V), as specified in the Electrical Characteristics table. This ultra-low shutdown current makes it suitable for battery-backed or always-on subsystems where standby power budget is tightly constrained.