STMicroelectronics LE45CD-TR

Overview

LE45CD-TR from STMicroelectronics is a very low-dropout linear voltage regulator delivering 4.5 V output at up to 100 mA, featuring 0.2 V typical dropout voltage, 50 µA typical quiescent current in OFF mode, and ±2% output voltage accuracy at 25 °C. It integrates TTL-compatible inhibit control (pin 5), internal current/thermal limiting, and operates across –40 to 125 °C - ideal for battery-powered sensor nodes and low-noise microcontroller power rails.

For engineers reviewing the LE45CD-TR datasheet, LE45CD-TR pinout, LE45CD-TR application, or LE45CD-TR equivalent, key selection criteria include dropout performance under 100 mA load, shutdown current behavior across temperature, SO-8 thermal resistance (R_thJA = 55 °C/W), and compatibility with 2.2 µF ceramic output capacitance for stability.

Technical Context

The LE45CD-TR implements a PNP pass transistor architecture with integrated error amplifier, reference, and inhibit logic - enabling precise 4.5 V regulation with minimal headroom. Its SO-8 package fuses pins 2, 3, 6, and 7 to the die attach pad, reducing thermal resistance (R_thJC = 20 °C/W) for improved power dissipation when PCB copper heatsinking is applied.

Inhibit functionality is active-low: grounding pin 5 disables regulation (quiescent current drops to 50 µA typ.), while floating or pulling high enables operation. The device requires no external compensation beyond a 2.2 µF output capacitor (ESR 0.1–10 Ω) and exhibits 77 dB supply voltage rejection at 120 Hz.

Key Specifications

Pinout & Package

LE45CD-TR is supplied in an SO-8 package (ECOPACK® compliant) with exposed thermal pad connected internally to pins 2, 3, 6, and 7. This configuration reduces thermal resistance and enables efficient heat transfer to PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LDL114M45R and TLV70745PDQNR, LE45CD-TR uniquely balances ultra-low dropout (0.2 V), industry-standard SO-8 footprint, and TTL-compatible inhibit - making it optimal for drop-in upgrades of L78L-based systems requiring precise 4.5 V with intelligent power control.

Availability

LE45CD-TR is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body electronics, medical wearables, and smart meter auxiliary rails requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LE45CD-TR 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 LEXX series was developed specifically for low-power, low-noise local regulation in battery-operated and thermally constrained systems - emphasizing dropout efficiency, shutdown current minimization, and robustness across extended temperature ranges.

FAQ

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

The LE45CD-TR 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 0.5 V dropout (–40 to 125 °C), input must be ≥5.0 V. Input voltage must not exceed 18 V per absolute maximum ratings.

Can the INH pin be left unconnected, or must it be tied to a defined logic level?

The INH pin must not be left floating: if unused, it must be grounded to prevent noise-induced toggling. Floating INH defaults to ON mode but risks erratic shutdown due to EMI coupling. For guaranteed OFF state, drive INH ≤0.8 V; for guaranteed ON, drive ≥2 V with ≤10 µA input current.

Is the 2.2 µF output capacitor mandatory, and what type is recommended?

Yes - a 2.2 µF ceramic capacitor (X5R or X7R dielectric) with ESR between 0.1 Ω and 10 Ω is required for stability per ST's test conditions. Tantalum or aluminum electrolytic capacitors are not recommended due to higher ESR and aging effects that may cause oscillation or poor transient response.

How does thermal performance differ between SO-8 and TO-92 packages for this device?

SO-8 offers R_thJA = 55 °C/W with proper PCB copper heatsinking (pins 2/3/6/7 connected to thermal pad), while TO-92 has R_thJA = 200 °C/W. At 100 mA and 10 V input, SO-8 junction rise is ~275 °C/W × 0.1 A × (10−4.5)V ≈ 15 °C above ambient - well within –40 to 125 °C rating. TO-92 would exceed limits under same conditions.