STMicroelectronics LDK220M40R

Overview

LDK220M40R from STMicroelectronics is a fixed-output 4.0 V, 200 mA low-dropout linear regulator in SOT23-5L package, featuring 100 mV typical dropout at 100 mA, ±2.0% output voltage accuracy at 25 °C, and logic-controlled shutdown with <1 µA off-mode current. It supports ceramic output capacitors as low as 1 µF and operates across -40 °C to 125 °C for battery-powered consumer and industrial power rails.

For engineers reviewing the LDK220M40R datasheet, LDK220M40R pinout, LDK220M40R application, or LDK220M40R equivalent, key selection criteria include dropout performance at light-to-full load, EN pin threshold stability over temperature, output noise (20 µVRMS/V, 10 Hz–100 kHz), and compatibility with 1 µF ceramic COUT in space-constrained designs.

Technical Context

The LDK220M40R implements a bandgap-referenced op-amp control loop with internal current limiting and thermal shutdown (160 °C trip, 20 °C hysteresis). Its enable input accepts logic-level signals (V_IL ≤ 0.4 V, V_IH ≥ 1.2 V) and activates an internal discharge path (R_dis = 18 Ω) when pulled low, preventing floating output during shutdown.

It delivers stable regulation across 2.5 V to 13.2 V input range with static line regulation of 0.001–0.05 %/V and load regulation of 0.001–0.003 %/mA, while maintaining 55 µA typical quiescent current across -40 °C to 125 °C ambient - critical for always-on subsystems in set-top boxes and portable instrumentation.

Key Specifications

Pinout & Package

LDK220M40R is packaged in SOT23-5L - a 5-pin, surface-mount plastic package (2.95 mm × 1.60 mm × 1.45 mm) with exposed thermal pad (not electrically connected), optimized for PCB heat dissipation in high-density layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, 200 mA LDO applications.

Compared with XC6219B402MR-G and AP2204K-4.0TRG1, LDK220M40R uniquely combines 200 mA capability, 100 mV dropout, EN control, and integrated discharge - making it the sole option among the three for thermally demanding, sequenced, and battery-critical 4.0 V rails.

Availability

LDK220M40R is available at Aetrix Electronics and suitable for portable medical sensors, set-top box power management, industrial PLC I/O modules, and laptop embedded controller rails requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for LDK220M40R 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, sensors, and analog components for industrial, automotive, and consumer markets.

The LDK220 series belongs to ST's precision low-noise LDO portfolio, engineered specifically for battery-powered and noise-sensitive applications where ultra-low I_Q, tight output tolerance, and robust thermal behavior are mandatory.

FAQ

What is the minimum input voltage required for LDK220M40R to maintain regulation at 200 mA load?

The minimum input voltage is calculated as V_OUT + V_DROP = 4.0 V + 350 mV = 4.35 V (max dropout at 200 mA, 40–125 °C per Table 6). At room temperature, 4.1 V suffices due to 200 mV typical dropout. Input below this causes output collapse - design margin should include worst-case thermal and tolerance conditions.

Can LDK220M40R be used with a 10 µF aluminum electrolytic capacitor instead of ceramic for COUT?

No - the LDK220M40R requires low-ESR ceramic capacitors (1–22 µF) for stability, as confirmed by Figure 22's stability boundary and Section 3's "Compatible with ceramic capacitor COUT = 1 µF" statement. Aluminum electrolytics typically exceed 1 Ω ESR and will cause oscillation or poor transient response.

Is the ADJ pin on LDK220M40R internally connected or should it be left floating?

The ADJ pin is Not Connected (NC) on the fixed-output LDK220M40R variant, as stated in Table 1 (SOT23-5L pin description) and confirmed by ordering code "M40R" (4.0 V fixed). It must remain unconnected - no pull-up, pull-down, or routing - to avoid unintended interaction with internal circuitry.

How does the output discharge function behave when EN is pulled low, and what is its impact on system design?

When EN is driven low, the internal 18 Ω discharge path actively sinks current from VOUT to GND, discharging COUT within ~10 ms (τ = R × C = 18 Ω × 1 µF). This prevents backfeed into upstream supplies and ensures downstream logic resets cleanly - but external voltage must never be applied to VOUT during discharge, per datasheet warning in Figure 2.