STMicroelectronics LDK320M18R

Overview

LDK320M18R from STMicroelectronics is a 1.8 V fixed-output, 200 mA low-dropout linear regulator with 100 mV typical dropout at 100 mA, ±2% output voltage accuracy over –40 °C to 125 °C, and 88 dB PSRR at 120 Hz. It operates from 2.5 V to 18 V input, supports logic-controlled shutdown (I_OFF < 1 μA), and is stable with 1 μF ceramic output capacitors. Designed for power management in compact consumer electronics requiring high accuracy and low quiescent current.

For engineers reviewing the LDK320M18R datasheet, LDK320M18R pinout, LDK320M18R application, or LDK320M18R equivalent, this page delivers verified electrical specs, SOT23-5L and SOT-89 package details, thermal protection behavior, load/line regulation performance, and real-world use cases in battery-powered DSC, BD/DVD, and industrial control systems.

Technical Context

The LDK320M18R implements a bandgap-referenced op-amp control loop with internal bias generator and thermal shutdown circuitry. Its architecture enables ultra-low dropout operation via optimized pass transistor drive and supports fast transient response due to low output impedance and compatibility with low-ESR ceramic capacitors.

It features dual-package support: SOT23-5L includes dedicated EN and ADJ/NC pins for enable control and optional adjustability, while SOT-89 (D configuration) integrates IN, GND, and OUT on three leads plus thermal tab tied to GND-no enable or adjust functionality in that variant.

Key Specifications

Pinout & Package

LDK320M18R is available in two RoHS-compliant packages: SOT23-5L (small outline transistor, 5-pin) and SOT-89 (3-pin power package with thermal tab). The SOT23-5L variant supports enable control and is used for fixed- or adjustable-output versions; the SOT-89 (D configuration) offers higher thermal dissipation but no enable function.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout voltage regulation applications.

Compared with TLV73318PDBVR and MCP1700T-1802E/TT, LDK320M18R delivers superior PSRR (88 dB vs ≤60 dB), lower dropout (100 mV vs ≥170 mV), and integrated thermal/current/SOA protection - making it optimal for reliability-critical industrial and consumer power rails where noise immunity and fault resilience are mandatory.

Availability

LDK320M18R is available at Aetrix Electronics and suitable for digital still cameras, Blu-ray/DVD players, industrial programmable logic controllers, and PC peripheral interface modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDK320M18R 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 LDK320 series belongs to ST's high-accuracy, high-PSRR LDO portfolio targeting battery-powered and noise-sensitive applications - engineered for minimal dropout, ultra-low quiescent current, and robust protection in compact SOT23-5L and SOT-89 packages.

FAQ

What is the minimum input voltage required for LDK320M18R to maintain regulation at full 200 mA load?

The minimum input voltage is determined by dropout voltage plus nominal output: V_IN(min) = V_OUT + V_DROP. At 200 mA and 125 °C, V_DROP reaches 350 mV (max), so V_IN(min) = 1.8 V + 0.35 V = 2.15 V. However, the absolute minimum specified operating input is 2.5 V per datasheet - thus 2.5 V is the guaranteed functional lower limit under all conditions.

Can LDK320M18R be used with tantalum or aluminum electrolytic output capacitors?

No - the LDK320M18R is specifically characterized and stabilized for ceramic capacitors with 1 μF to 22 μF capacitance and ESR ≤1 Ω. Tantalum and aluminum electrolytics exhibit higher ESR and aging effects that may cause instability, overshoot, or oscillation. ST's datasheet explicitly recommends only X7R/X5R ceramics for reliable operation.

Is the EN pin internally pulled up or down, and what is its leakage current?

The EN pin has no internal pull-up or pull-down resistor and must be actively driven. Its input leakage current is specified as 0.1–100 nA (typ. 10 nA) when V_EN = V_IN, enabling direct connection to open-drain GPIOs or resistive dividers without significant loading. This allows flexible enable control using either active-high or active-low logic configurations with external pull resistors.

How does thermal performance differ between SOT23-5L and SOT-89 packages at 200 mA continuous load?

At 200 mA with V_IN = 5.8 V (1.8 V + 4 V headroom), power dissipation is ~0.8 W. SOT23-5L has R_thJA = 160 °C/W, yielding ΔT ≈ 128 °C rise above ambient - exceeding safe junction limits. SOT-89 has R_thJA = 110 °C/W and R_thJC = 15 °C/W; with proper PCB copper pour, it sustains 200 mA continuously at up to 85 °C ambient. Thus SOT-89 is mandatory for full-load industrial operation.