STMicroelectronics LE45CZ

Overview

LE45CZ from STMicroelectronics is a very low dropout (LDO) linear voltage regulator delivering 4.5 V ±2% output at up to 100 mA, with 0.2 V typical dropout at full load and 50 µA quiescent current in OFF mode. It features TTL-compatible inhibit control (pin 5 in SO-8), internal current/thermal limiting, and stable operation with only 2.2 µF output capacitance-optimized for battery-powered systems requiring low-noise, low-power local regulation.

For engineers reviewing the LE45CZ datasheet, LE45CZ pinout, LE45CZ application, or LE45CZ equivalent, this device is selected for precision low-dropout regulation in space-constrained, thermally sensitive, or energy-harvesting designs where shutdown control and minimal external components are critical.

Technical Context

The LE45CZ implements a PNP pass transistor architecture enabling ultra-low dropout voltage (0.2 V typ. at 100 mA) and high PSRR (80 dB typ. at 120 Hz). Its inhibit function uses a dedicated TTL-compatible input that forces the regulator into high-impedance OFF state when pulled low, reducing total system standby current.

It operates across –40 °C to +125 °C junction temperature and supports input voltages up to 18 V. The SO-8 package integrates pins 2, 3, 6, and 7 to the die attach flag for enhanced thermal dissipation (R_thJA = 55 °C/W), while the TO-92 variant maintains continuous ON-state operation without inhibit capability.

Key Specifications

Pinout & Package

LE45CZ is available in SO-8 (ECOPACK®) and TO-92 packages. The SO-8 variant includes an inhibit control pin (pin 5), while the TO-92 version operates continuously without shutdown capability. Both use the same pin numbering: pin 1 = V_OUT, pin 2 = GND, pin 3 = V_IN.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LE45AB, LE45CZ trades ±1% accuracy for lower cost and broader tolerance margin; versus LDL1145, it adds shutdown control and higher thermal capability at the expense of larger package size and slightly higher quiescent current.

Availability

LE45CZ is available at Aetrix Electronics and suitable for battery-powered sensor nodes, automotive body control modules, industrial PLC I/O modules, and medical wearable monitors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LE45CZ 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 devices for industrial, automotive, and consumer markets.

The LE series LDO regulators were developed specifically for low-power, low-noise, and thermally demanding applications-including portable instrumentation, automotive sub-systems, and industrial edge nodes-where dropout voltage, quiescent current, and package thermal performance are critical selection criteria.

FAQ

What is the minimum input voltage required for stable 4.5 V output at 100 mA?

The LE45CZ requires a minimum input voltage of 4.7 V to maintain regulation at 100 mA load, based on its 0.2 V typical dropout voltage. At worst-case conditions (–40 °C to +125 °C, 100 mA), dropout rises to 0.5 V, so 5.0 V input ensures margin. Input must not exceed 18 V per absolute maximum ratings.

Can the LE45CZ be used without the inhibit pin in SO-8 configuration?

Yes - if inhibit functionality is unused, pin 5 must be tied to V_IN (≥2.0 V) to ensure ON operation, or grounded only if the system guarantees no noise coupling. Leaving it floating is discouraged due to potential noise-induced oscillation; STMicroelectronics recommends connecting it to V_IN or GND via a pull-up/down resistor.

Is the 2.2 µF output capacitor mandatory, or can a smaller value be used?

The 2.2 µF value is the minimum recommended for guaranteed stability across all operating conditions (load, temperature, input voltage). Using a smaller capacitor risks oscillation or poor transient response. Ceramic capacitors with ESR between 0.1 Ω and 10 Ω are required; tantalum or aluminum electrolytics are not recommended due to ESR drift and aging effects.

How does the thermal performance differ between SO-8 and TO-92 packages?

The SO-8 package achieves R_thJA = 55 °C/W with adequate PCB copper pour, enabling 100 mA continuous operation at +85 °C ambient. The TO-92 package has R_thJA = 200 °C/W, limiting practical continuous current to ~25 mA at +85 °C ambient without forced airflow or heatsinking - making SO-8 the choice for higher-power or thermally constrained designs.