STMicroelectronics LK115D50

Overview

LK115D50 from STMicroelectronics is a very low-dropout linear voltage regulator delivering 5.0 V at up to 100 mA output current, featuring 0.17 V typical dropout at 60 mA, ±3% output voltage tolerance at 25 °C, and dual logic-controlled shutdown (active-HIGH on pin 2, active-LOW on pin 3). It targets battery-powered systems requiring ultra-low quiescent current (0.01 µA in off mode) and high PSRR (75 dB at 120 Hz).

For engineers reviewing the LK115D50 datasheet, LK115D50 pinout, LK115D50 application, or LK115D50 equivalent, key selection criteria include dual shutdown control logic compatibility, SO-8 footprint constraints, 2.2 µF minimum output capacitance requirement, and operation across –40 °C to 125 °C junction temperature range.

Technical Context

The LK115D50 integrates internal current and thermal limiting, operates with input voltages up to 20 V, and maintains regulation down to VI = VO + Vd (5.17 V min at 60 mA). Its supply voltage rejection is frequency-dependent: 75 dB at 120 Hz, dropping to 55 dB at 10 kHz.

Shutdown is implemented via two independent digital inputs: pin 2 accepts active-HIGH logic (0–0.5 V OFF, 2.4–VI ON), while pin 3 accepts active-LOW logic (VI–0.2–VI OFF, 0–VI–2.4 V ON); the truth table forbids simultaneous LOW on both pins.

Key Specifications

Pinout & Package

Package: SO-8 (ECOPACK®, lead-free, JEDEC standard). Dimensions per ST mechanical drawing: D = 4.80–5.00 mm, E = 3.80–4.00 mm, e = 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV70550DBVR and MCP1825-5002E/DB, the LK115D50 uniquely balances 100 mA capability, dual independent shutdown, and sub-0.2 V dropout - making it optimal for battery-powered systems needing flexible power-state control without sacrificing output current or thermal margin.

Availability

LK115D50 is available at Aetrix Electronics and suitable for wireless sensor nodes, automotive body controllers, and industrial PLC I/O modules requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for LK115D50 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 automotive-grade components.

The LK115XX series was developed specifically for ultra-low-power, high-reliability embedded systems - emphasizing minimal dropout, dual shutdown flexibility, and robust operation across extended temperature ranges.

FAQ

What is the minimum input voltage required for regulation at full 100 mA load?

The LK115D50 maintains regulation down to VIN = VOUT + Vd. At 100 mA, the maximum dropout is 0.2 V (per absolute max characterization), so minimum input is 5.2 V. However, datasheet test data shows 0.17 V typical at 60 mA; for 100 mA, design margin requires ≥5.25 V input to guarantee regulation across temperature and process variation.

Can both shutdown pins be driven simultaneously, and what happens if they conflict?

No - the truth table explicitly states "L H NOT ALLOWED" when pin 2 is LOW and pin 3 is HIGH. This condition violates internal logic and may cause undefined behavior or increased quiescent current. The device must be operated only in the three defined states: H/L (ON), H/H (OFF), or L/L (OFF).

Is an input bypass capacitor required, and what value is recommended?

Yes - a 0.1 µF ceramic capacitor (X5R/X7R) is required on the input pin (pin 1) per Figure 3 and Table 4 test conditions. It stabilizes the internal reference and improves transient response. Place it within 3 mm of pin 1 with short, low-inductance traces to prevent oscillation during load steps.

Does the LK115D50 support reverse-voltage protection or current limiting during short-circuit events?

Yes - the datasheet specifies internal current and thermal limiting. Short-circuit protection activates at ~120–200 mA (per Table 4), folding back output current to limit power dissipation. Thermal shutdown engages above 150 °C junction temperature. However, no reverse-voltage protection is integrated - external diode or MOSFET is required if reverse polarity is possible.