STMicroelectronics LE50ABD

Overview

LE50ABD from STMicroelectronics is a 5.0 V fixed-output, very low dropout (0.2 V typ. at 100 mA) linear voltage regulator in SO-8 package with TTL-compatible inhibit control (pin 5), ±1% output voltage accuracy at 25 °C, and operation across –40 to 125 °C. It delivers up to 100 mA output current, draws only 0.5 mA quiescent current in ON mode (no load), and requires just 2.2 µF output capacitance for stability - making it ideal for space-constrained, battery-powered microcontroller subsystems.

For engineers reviewing the LE50ABD datasheet, LE50ABD pinout, LE50ABD application, or LE50ABD equivalent, key selection considerations include its precise 5.0 V output tolerance, ultra-low dropout under full load, shutdown logic interface for system-level power sequencing, and thermal performance in SO-8 with internal die-attach flag for enhanced heatsinking.

Technical Context

The LE50ABD integrates an internal current-limit and thermal shutdown circuit, enabling robust protection without external components. Its inhibit input accepts TTL-level logic (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) and places the regulator in ultra-low-power OFF mode (50 µA typical I_Q) when asserted - critical for standby power budgeting in portable instrumentation.

Designed as a pin-to-pin upgrade to the legacy L78Lxx series, it retains identical footprint compatibility while improving dropout voltage by >60% and reducing quiescent current in ON mode by ~50%. The SO-8 variant uses pins 2, 3, 6, and 7 internally connected to the die attach flag, lowering R_thJA to 55 °C/W with PCB copper pour.

Key Specifications

Pinout & Package

LE50ABD is housed in an SO-8 package with internal die-attach flag connected to pins 2, 3, 6, and 7 for improved thermal dissipation. Pin 5 is the TTL-compatible inhibit input; floating defaults to ON mode but must be grounded if unused to prevent noise-induced shutdown.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LDL1117S50R and TPS73550DRVR, LE50ABD uniquely combines ±1% accuracy, SO-8 thermal flag for 100 mA continuous operation, and TTL-compatible active-low inhibit - making it optimal for cost-sensitive, thermally constrained, and battery-life-critical 5 V subsystems where legacy L78L50 replacement is required.

Availability

LE50ABD is available at Aetrix Electronics and suitable for portable medical devices, automotive body electronics, industrial PLC I/O modules, and smart meter communication subsystems requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance.

Supply support for LE50ABD 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 LE series was developed specifically for ultra-low-power, high-accuracy local regulation in battery-operated and thermally demanding embedded systems - emphasizing dropout voltage reduction, quiescent current optimization, and seamless drop-in replacement of legacy linear regulators.

FAQ

What is the minimum input voltage required for stable 5.0 V output at 100 mA?

The LE50ABD maintains regulation down to V_IN = V_OUT + V_DROP. With a typical dropout of 0.2 V at 100 mA and maximum of 0.5 V across temperature, the minimum input is 5.2 V (typ.) or 5.5 V (guaranteed over –40 to 125 °C). Input below this causes output collapse or unregulated behavior.

Can the inhibit pin be left unconnected, or does it require a pull-up/down resistor?

The inhibit pin must not be left floating. Per datasheet Note in Section 3, an unconnected INH may pick up noise and cause erratic ON/OFF toggling. When inhibition is unused, tie pin 5 directly to GND to ensure reliable ON operation and avoid false shutdowns.

Is the SO-8 package thermally enhanced, and how should the thermal flag be implemented on the PCB?

Yes - pins 2, 3, 6, and 7 are internally connected to the die attach flag. For optimal thermal performance, these pins must be soldered to a minimum 100 mm² copper pour (≥2 oz thickness) with ≥4 thermal vias (0.3 mm diameter) connecting to inner/ground planes. This achieves the rated R_thJA of 55 °C/W.

Does LE50ABD require a specific ESR range for the 2.2 µF output capacitor?

Yes - the datasheet specifies stability with output capacitors having ESR between 0.1 Ω and 10 Ω. Standard X5R/X7R ceramic capacitors (e.g., 2.2 µF, 10 V, 0805) typically exhibit 10–30 mΩ ESR and are fully compatible. Avoid ultra-low-ESR polymer or tantalum types unless validated per application note AN2719.