STMicroelectronics LK115D33

Overview

LK115D33 from STMicroelectronics is a very low-dropout linear voltage regulator delivering 3.3 V at up to 100 mA output current, featuring 0.17 V typical dropout voltage, ±3% output tolerance at 25 °C, and dual logic-controlled shutdown (pins 2 and 3). It operates across –40 °C to 125 °C and targets battery-powered microcontroller subsystems requiring ultra-low quiescent current (0.01 µA in off mode).

For engineers reviewing the LK115D33 datasheet, LK115D33 pinout, LK115D33 application, or LK115D33 equivalent, key selection criteria include dual active-HIGH/active-LOW enable control, 2.2 µF minimum output capacitance for stability, 72.6 µV RMS output noise, 79 dB supply voltage rejection at 120 Hz, and SO-8 package compatibility with space-constrained PCB layouts.

Technical Context

The LK115D33 integrates internal current and thermal limiting, enabling robust operation without external protection circuitry. Its dual ON/OFF control pins support flexible power sequencing: pin 2 (active-HIGH) and pin 3 (active-LOW) allow independent or coordinated shutdown of local subsystems.

It achieves stable regulation with only a 2.2 µF ceramic output capacitor (ESR 0.5–10 Ω), eliminating need for bulk electrolytics. The regulator maintains 3.3 V output under line regulation drift ≤10 mV (VI = 4.3–20 V) and load regulation drift ≤20 mV (IO = 0.5–100 mA).

Key Specifications

Pinout & Package

Supplied in an SO-8 surface-mount package (ECOPACK®, lead-free, JEDEC-compliant), the LK115D33 uses standard 1.27 mm pitch with 5.0 × 4.0 mm body dimensions and 1.75 mm max height.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TSM1033IDT and LDL1133PU33R, the LK115D33 uniquely combines dual logic-enable control, sub-µA off-state IQ, and SO-8 thermal performance-making it optimal for battery-powered systems needing selective subsystem shutdown and long shelf life.

Availability

LK115D33 is available at Aetrix Electronics and suitable for wireless sensor nodes, automotive body electronics, industrial PLC I/O modules, and portable medical diagnostics requiring stable component supply across extended temperature ranges and low-power operation.

Supply support for LK115D33 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 LK115XX series was developed specifically for ultra-low-power, high-reliability local regulation in battery-operated and thermally demanding environments-emphasizing minimal external components and dual-control flexibility.

FAQ

What is the minimum input voltage required for stable 3.3 V output at 100 mA?

The LK115D33 requires VIN ≥ VOUT + VDROPOUT = 3.3 V + 0.17 V = 3.47 V minimum at 60 mA; at 100 mA, worst-case dropout is 0.2 V, so VIN ≥ 3.5 V ensures regulation. Input must also meet absolute minimum of 4.3 V per electrical characteristics table for full spec compliance.

Can both enable pins (2 and 3) be used simultaneously, and what happens if conflicting logic is applied?

No-simultaneous conflicting states are prohibited. Table 2 explicitly defines "L H" (pin 2 low, pin 3 high) as NOT ALLOWED. If asserted, the device enters undefined behavior; design must ensure only valid combinations (H/L = ON, H/H or L/L = OFF) are applied per truth table.

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

Yes-an input capacitor is required for stability and transient response. ST recommends 0.1 µF ceramic (CI) placed close to VIN and GND pins. This value is specified in all test circuits (Tables 4–6) and prevents oscillation during load steps or input line impedance variations.

Does the LK115D33 support reverse-voltage protection or current limiting during short-circuit events?

Yes-the device includes internal current limiting (120–200 mA trip range) and thermal shutdown. Under short-circuit, it folds back output current and throttles junction temperature to prevent damage. However, it does not provide reverse-input polarity protection; external diode is required if reverse voltage >0.3 V may occur.