STMicroelectronics LDK120C11R

Overview

LDK120C11R from STMicroelectronics is a 200 mA, 1.1 V fixed-output low-dropout linear regulator with 100 mV typical dropout at 100 mA, 100 µA max quiescent current, ±2.0% output voltage tolerance at 25 °C, and operation from 1.9 V to 5.5 V input. It delivers ultra-low-noise power for RF-sensitive analog circuitry in compact battery-powered devices.

For engineers reviewing the LDK120C11R datasheet, LDK120C11R pinout, LDK120C11R application, or LDK120C11R equivalent, key selection criteria include its 1.1 V fixed output, SOT323-5L package footprint, shutdown current <1 µA, ceramic capacitor compatibility (COUT = 1 µF), and thermal/short-circuit protection - all critical for space-constrained portable electronics design.

Technical Context

The LDK120C11R employs a PMOS pass transistor architecture enabling ultra-low dropout and near-zero gate-drive current, eliminating external bias requirements. Its internal bandgap reference and error amplifier maintain tight regulation across –40 °C to 125 °C junction temperature.

Logic-controlled enable (EN) pin provides precise system-level power sequencing with 0.4 V logic-low threshold and 1.2 V logic-high threshold. The device integrates thermal shutdown with 160 °C trip point and 20 °C hysteresis, plus constant-current short-circuit limiting at 400 mA.

Key Specifications

Pinout & Package

LDK120C11R is packaged in SOT323-5L - a 1.8 mm × 2.0 mm × 0.9 mm surface-mount package with 0.65 mm pitch, optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, low-IQ LDO applications.

Compared with XC6210B112MR-G and RT9013-11GB, the LDK120C11R uniquely balances 200 mA drive, 100 mV dropout, integrated thermal/short-circuit protection, and SOT323-5L footprint - making it optimal for space-constrained, thermally demanding portable designs requiring robustness and noise performance.

Availability

LDK120C11R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, and cordless phone systems requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for LDK120C11R 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 microcontrollers, power management ICs, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The LDK120 series belongs to ST's high-performance LDO portfolio targeting battery-powered portable electronics, emphasizing ultra-low quiescent current, low noise, and small-footprint packaging for miniaturized end equipment.

FAQ

What is the recommended output capacitor for LDK120C11R?

A 1 µF X5R/X7R ceramic capacitor placed within 2 mm of the OUT and GND pins is mandatory for stability and transient response. Larger values (up to 22 µF) improve PSRR but require verification against ESR limits shown in Figure 25 of the datasheet. Tantalum or electrolytic capacitors are not required or recommended.

Can LDK120C11R operate with an input voltage below 1.9 V?

No - the absolute minimum input voltage is 1.9 V per datasheet Section 4 (Table 2). Operation below this risks loss of regulation, increased dropout, or undefined behavior. For sub-1.9 V inputs, consider ST's STLQ015 series or alternative ultra-low-VIN LDOs with verified 1.0 V operation.

Is the BYP pin on LDK120C11R required to connect to ground or a capacitor?

No - for the fixed-output LDK120C11R, Pin 4 (BYP/NC) is internally not connected and must be left floating with no PCB trace or solder pad. Connecting it to ground or a capacitor violates the datasheet specification and may cause instability or parametric shift.

How does thermal shutdown behave during sustained overload?

When junction temperature reaches 160 °C, thermal shutdown activates, disabling the pass transistor and reducing output current to near zero. After cooling by ≥20 °C (hysteresis), the device automatically recovers without external intervention - a self-protecting feature validated across –40 °C to 125 °C ambient conditions.