STMicroelectronics LD57100J105R

Overview

LD57100J105R from STMicroelectronics is a 1 A ultra-low-dropout linear regulator (LDO) with NMOS pass transistor and dedicated VBIAS pin, delivering 1.05 V output at ±1% accuracy over −40 °C to +85 °C. It achieves 40 mV typical dropout at full load, draws only 35 µA quiescent current at no load, and integrates logic-controlled shutdown and active output discharge-optimized for smartphone and camera power rails requiring tight regulation and minimal board space.

For engineers reviewing the LD57100J105R datasheet, LD57100J105R pinout, LD57100J105R application, or LD57100J105R equivalent, key selection criteria include bias-supplied ultra-low-drop operation, 0.8×1.2 mm Flip Chip6 package constraints, thermal shutdown at 160 °C, and compatibility with ceramic output capacitors ≥1 µF for post-regulation in battery-powered systems.

Technical Context

The LD57100J105R uses an NMOS pass element driven by a separate VBIAS supply (3.0–5.5 V), enabling stable regulation even when VIN approaches VOUT-critical for low-headroom applications like core voltage scaling in mobile SoCs. Its internal reference (0.5 V ±0.5%) feeds a precision error amplifier that controls gate drive under varying load and temperature.

It features dual supply rejection: 75 dB VIN PSRR and 85 dB VBIAS PSRR at 1 kHz, plus 27 µVRMS integrated output noise (10 Hz–100 kHz) for noise-sensitive analog/RF blocks. The SNS/FB pin supports either fixed-output sensing (via dedicated trace) or adjustable feedback (via resistor divider), while EN enables <0.1 µA shutdown current.

Key Specifications

Pinout & Package

LD57100J105R is housed in a 6-terminal Flip Chip6 package (0.8 × 1.2 mm, 0.4 mm pitch), optimized for minimal footprint and thermal performance on dense mobile PCBs. The die-down configuration provides direct thermal path to PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B105MR-G and RT9080L-105GJ6F, LD57100J105R delivers the smallest footprint, lowest dropout, and highest VBIAS PSRR-making it optimal for space-constrained, ultra-low-voltage, noise-critical mobile power rails where every millivolt and square millimeter matters.

Availability

LD57100J105R is available at Aetrix Electronics and suitable for smartphone power management, camera module regulation, wearable display rails, and low-power IoT sensor nodes requiring stable component supply across production lifecycles.

Supply support for LD57100J105R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD57100 series belongs to ST's high-accuracy, ultra-low-dropout LDO product line, engineered specifically for post-regulation in battery-powered mobile devices where minimal voltage overhead, low quiescent current, and small form factor are non-negotiable.

FAQ

What is the minimum input voltage required for LD57100J105R to regulate at 1.05 V?

The minimum input voltage is determined by dropout: at 1 A load, 40 mV typical dropout means VIN must be ≥1.09 V. Per datasheet Table 6, recommended operating VIN starts at 0.6 V-but stable regulation at full current requires VIN ≥ VOUT + VDROP. Below 1.09 V, output collapses proportionally.

Can the VBIAS pin be connected directly to VIN?

Yes-if VIN meets both conditions: ≥3.0 V and ≥VOUT + 1.6 V (i.e., ≥2.65 V for 1.05 V output). Since 1.05 V + 1.6 V = 2.65 V, and VIN must be ≥1.09 V for regulation, tying VBIAS to VIN is valid only when VIN ≥3.0 V. Otherwise, a separate 3.0–5.5 V bias rail is mandatory.

Does LD57100J105R require an external resistor divider for output setting?

No. LD57100J105R is the fixed-output variant (1.05 V); it uses the SNS pin for remote output sensing-not feedback. Resistor dividers apply only to the adjustable version (LD57100JR). For J105R, connect SNS directly to the load via a dedicated PCB trace to compensate for trace resistance.

How does the output discharge function behave during shutdown?

When EN is pulled low, the internal 150 Ω NMOS switch between VOUT and GND activates, discharging the output capacitor. Typical discharge time for a 10 µF capacitor is <1 ms (τ = R × C ≈ 150 Ω × 10 µF = 1.5 ms), ensuring rapid rail collapse to prevent back-powering downstream circuitry or violating sequencing requirements.