Texas Instruments LP38859S-1.2/NOPB

Overview

LP38859S-1.2/NOPB from Texas Instruments is a 3-A, fast-response, high-accuracy LDO linear regulator with dual-rail operation (VIN and VBIAS), 1.2 V fixed output, 240 mV typical dropout at 3 A, ±1% output accuracy at 25°C, and programmable soft-start via external capacitor. It powers DSP/FPGA core rails and SMPS post-regulation stages in high-density computing systems.

For engineers reviewing the LP38859S-1.2/NOPB datasheet, LP38859S-1.2/NOPB pinout, LP38859S-1.2/NOPB application, or LP38859S-1.2/NOPB equivalent, this page delivers verified package mapping (DDPAK/TO-263, 5-pin), confirmed thermal metrics (RθJA = 43.2°C/W), real-world stability data (stable with 10-µF ceramic COUT), and precise soft-start timing derivation (rSS = 16 kΩ).

Technical Context

The LP38859S-1.2/NOPB uses an N-MOS pass transistor driven by a dedicated VBIAS rail (3–5.5 V), enabling ultra-low VIN operation down to 1.1 V while maintaining regulation. Its CMOS architecture delivers low quiescent current (11–12 mA from VIN, 3–4.5 mA from VBIAS) across full load range.

It integrates undervoltage lockout (UVLO threshold ≈2.45 V, 150 mV hysteresis), thermal shutdown (160°C, 10°C hysteresis), and overcurrent protection. Soft-start is implemented via internal 16 kΩ resistor charging external CSS, yielding tSS = CSS × 16 kΩ × 5 - e.g., 10 nF yields 800 µs typical rise time.

Key Specifications

Pinout & Package

LP38859S-1.2/NOPB is housed in a 5-pin DDPAK/TO-263 package (10.16 mm × 8.42 mm) with exposed thermal tab electrically connected to GND. The tab must be soldered to a large PCB ground plane for optimal thermal performance (RθJC(bot) = 1.1°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A8300RGRT and LT3080IMSE#PBF, LP38859S-1.2/NOPB uniquely supports ultra-low VIN (1.1 V) via dual-rail architecture, delivers full 3-A current with 240-mV dropout, and provides factory-trimmed 1.2 V accuracy without external components - making it optimal for high-density, thermally constrained core-rail applications.

Availability

LP38859S-1.2/NOPB is available at Aetrix Electronics and suitable for ASIC power supplies, SMPS post-regulation, DSP/FPGA core rails, and server I/O voltage rails requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LP38859S-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 technologies, with decades of LDO design expertise and broad industrial qualification.

The LP38859 product line targets high-current, high-accuracy point-of-load regulation in computing, telecom, and industrial systems - emphasizing fast transient response, dual-rail flexibility, and thermal resilience in compact packages.

FAQ

What is the minimum input voltage required for LP38859S-1.2/NOPB to regulate 1.2 V output?

The LP38859S-1.2/NOPB requires VIN ≥ VOUT + VDO. With a typical dropout voltage of 240 mV at 3 A, the minimum functional VIN is 1.44 V. However, the device can accept VIN as low as 1.1 V - regulation is only guaranteed when VIN meets or exceeds the dropout threshold relative to the 1.2 V output. Below that, VOUT drops proportionally.

How is soft-start time calculated for LP38859S-1.2/NOPB?

Soft-start time for LP38859S-1.2/NOPB is calculated as tSS = CSS × rSS × 5, where rSS = 16 kΩ (typical). For example, a 10 nF capacitor yields tSS = 10 nF × 16 kΩ × 5 = 800 µs. This exponential ramp controls VOUT rise to limit inrush current into COUT and downstream loads.

Can LP38859S-1.2/NOPB operate without a VBIAS supply?

No. LP38859S-1.2/NOPB requires a valid VBIAS supply between 3 V and 5.5 V to power its internal control circuitry and gate driver. If VBIAS falls below the UVLO threshold (~2.45 V), the device disables output regardless of VIN level. VBIAS is mandatory - there is no single-rail mode.

What capacitor types are recommended for COUT on LP38859S-1.2/NOPB?

LP38859S-1.2/NOPB requires ≥10 µF of X5R or X7R ceramic capacitance at the output for guaranteed stability. Z5U and Y5F ceramics are excluded due to insufficient capacitance retention over temperature. Tantalum or aluminum electrolytics may be added in parallel but are not substitutes for the minimum 10 µF ceramic.

Does LP38859S-1.2/NOPB include reverse-voltage protection?

LP38859S-1.2/NOPB has inherent reverse-current blocking when VBIAS is below UVLO (gate un-driven), but offers no active reverse-voltage protection. If VBIAS is active (>2.45 V) and VOUT > VIN, reverse current flows through the NMOS pass element's RDS(ON). External diode clamping is required in negative-rail or hot-swap applications.