STMicroelectronics LDK120C25R

Overview

LDK120C25R from STMicroelectronics is a 2.5 V fixed-output, 200 mA low-dropout linear regulator with 100 µA max quiescent current, 100 mV typical dropout at 100 mA, and 51 µV_RMS output noise (10 Hz–100 kHz) using a 10 nF bypass capacitor - designed for power-sensitive mobile phone baseband and RF subsystems requiring stable low-noise bias.

For engineers reviewing the LDK120C25R datasheet, LDK120C25R pinout, LDK120C25R application, or LDK120C25R equivalent, this page delivers verified electrical specs, SOT323-5L package details, enable-controlled shutdown behavior, ceramic-capacitor stability validation, and real-world use cases in battery-powered portable electronics.

Technical Context

The LDK120C25R employs a PMOS pass transistor architecture enabling ultra-low dropout voltage and near-zero gate-drive current, eliminating external compensation requirements. Its internal bandgap reference and error amplifier deliver ±2.0% output voltage accuracy at 25 °C and ±3.0% over –40 °C to 125 °C.

Logic-controlled EN pin provides hard-shutdown with sub-1 µA total supply current; thermal shutdown activates at 160 °C with 20 °C hysteresis. The device achieves 55 dB supply voltage rejection from 120 Hz to 10 kHz and supports 1 µF to 22 µF ceramic output capacitors with defined ESR stability boundaries.

Key Specifications

Pinout & Package

LDK120C25R 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 space-constrained portable PCBs and compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B252MR-G and ADP160ACBZ-2.5-R7, the LDK120C25R uniquely balances 200 mA capability, 100 mV dropout, and 51 µV_RMS noise via its BYP pin - making it optimal for portable RF and imaging systems needing both headroom and spectral purity.

Availability

LDK120C25R is available at Aetrix Electronics and suitable for mobile phones, digital still cameras, and cordless phone systems requiring stable component supply with full production lifecycle support through July 2026.

Supply support for LDK120C25R 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 LDK120 series targets ultra-low-power portable electronics, emphasizing minimal quiescent current, ceramic-capacitor compatibility, and noise-suppressed regulation for battery-constrained devices.

FAQ

What is the minimum input voltage required for regulation at 2.5 V output?

The LDK120C25R maintains regulation as long as VIN ≥ VOUT + VDROP. With a typical dropout of 100 mV at 100 mA, the minimum functional input is 2.6 V. At 200 mA and elevated temperature, dropout rises to 300 mV, requiring VIN ≥ 2.8 V for guaranteed 2.5 V output.

Can the BYP pin be left unconnected without affecting basic regulation?

Yes - the BYP pin is optional and must be left floating (no PCB trace or connection) when unused. Leaving it unconnected disables the low-noise enhancement, resulting in 148 µV_RMS output noise instead of 51 µV_RMS, but does not impact regulation accuracy, dropout, or stability.

Is the LDK120C25R compatible with 1 µF X7R ceramic output capacitors?

Yes - the device is explicitly characterized and stabilized with 1 µF ceramic capacitors (X7R or better). Figure 25 confirms stable operation with C_OUT = 1 µF and ESR < 1 Ω; larger values up to 22 µF are also supported within defined ESR boundaries.

Does the EN pin require an external pull-up resistor?

No - the EN pin has internal biasing and operates as a CMOS-compatible logic input. It draws ≤100 nA and transitions cleanly between active (≥1.2 V) and shutdown (≤0.4 V) states without external components, simplifying GPIO interface design.