STMicroelectronics LE40CZ

Overview

LE40CZ from STMicroelectronics is a very low dropout linear voltage regulator delivering 4.0 V ±2% output at up to 100 mA, with 0.2 V typical dropout at full load, 50 µA quiescent current in OFF mode, and operation across –40 °C to +125 °C. 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 microcontroller subsystems and low-noise sensor rails.

For engineers reviewing the LE40CZ datasheet, LE40CZ pinout, LE40CZ application, or LE40CZ equivalent, this device is selected for ultra-low-power local regulation where shutdown control, thermal robustness in compact packages, and minimal external components are critical design requirements.

Technical Context

The LE40CZ implements a PNP pass transistor architecture enabling sub-0.3 V dropout while maintaining tight line/load regulation (≤20 mV) and high PSRR (80 dB @ 120 Hz). Its inhibit function uses a dedicated TTL-level input that forces the regulator into high-impedance OFF state with <100 µA supply current, independent of input voltage.

Thermal performance is enhanced by internal die-attach flag connection in SO-8 (R_thJA = 55 °C/W), while TO-92 variants operate continuously without inhibit logic. Both versions guarantee stability with ceramic capacitors as low as 2.2 µF and ESR between 0.1–10 Ω.

Key Specifications

Pinout & Package

LE40CZ is available in TO-92 (3-pin) and SO-8 (8-pin) packages. The TO-92 variant operates continuously (no inhibit), while SO-8 includes TTL-compatible shutdown control on pin 5. In SO-8, pins 2, 3, 6, and 7 are internally connected to the die attach flag for improved thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LDL114M40R and LP2951ACN-4.0, LE40CZ uniquely balances ultra-low dropout (0.2 V), integrated inhibit control, and automotive-grade temperature range - making it optimal for battery-sensitive systems requiring active power gating.

Availability

LE40CZ is available at Aetrix Electronics and suitable for portable medical devices, automotive body electronics, industrial PLC I/O cards, and smart meter subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LE40CZ 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 specializing in power management, microcontrollers, and automotive-grade analog ICs, with manufacturing and quality systems certified to AEC-Q100 and ISO/TS 16949.

The LE series LDOs were designed specifically for ultra-low-power, thermally demanding applications in automotive and industrial environments - emphasizing dropout minimization, wide temperature operation, and minimal external component count.

FAQ

What is the minimum input voltage required for LE40CZ to maintain regulation at 100 mA load?

The LE40CZ requires VIN ≥ VOUT + V_DROP. With a nominal 4.0 V output and 0.2 V typical dropout, 4.2 V input sustains regulation at 100 mA. At worst-case 0.5 V dropout (over temperature), 4.5 V input is recommended for guaranteed operation.

Can LE40CZ be used without the inhibit pin in SO-8 configuration?

Yes - the inhibit pin (pin 5) may be grounded to force permanent OFF state or tied to VIN (≥2.0 V) for permanent ON. If unused, ST recommends grounding it to prevent noise-induced toggling; floating defaults to ON but risks instability in noisy environments.

Is LE40CZ compatible with ceramic output capacitors?

Yes - LE40CZ is explicitly characterized for stability with 2.2 µF ceramic capacitors having ESR between 0.1 Ω and 10 Ω. No series resistor or special biasing is required, unlike older LDO architectures that demand higher-ESR tantalum types.

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

SO-8 offers significantly better thermal dissipation: R_thJA = 55 °C/W (with PCB copper heatsinking) versus 200 °C/W for TO-92. This allows SO-8 to deliver full 100 mA at +85 °C ambient, while TO-92 requires >30 °C derating above 25 °C ambient to avoid thermal shutdown.