STMicroelectronics L78L05ABUTR

Overview

L78L05ABUTR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 5 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components, operates across -40 °C to +125 °C junction temperature, and maintains ±4% output voltage tolerance over load, line, and temperature variations - ideal for local on-card regulation in industrial control modules.

For engineers reviewing the L78L05ABUTR datasheet, L78L05ABUTR pinout, L78L05ABUTR application, or L78L05ABUTR equivalent, this device serves as a robust, drop-in replacement for Zener diode/resistor regulators in low-power embedded systems where low quiescent current (6 mA typ.), low output noise (40 µV), and high supply voltage rejection (41–49 dB) are critical.

Technical Context

The L78L05ABUTR employs monolithic bipolar technology with built-in foldback current limiting and thermal shutdown circuitry, enabling self-protecting operation without external supervision. Its architecture integrates a precision bandgap reference, error amplifier, and pass transistor in a single die, optimized for stability with minimal 0.33 µF input and 0.1 µF output capacitance.

It functions as a fixed-output series regulator with a 2 V dropout voltage at 40 mA, supporting input voltages from 7 V to 20 V for reliable 5 V rail generation. The device's SO-8 package features pins 2, 3, 6, and 7 internally connected to the die attach flag, reducing thermal resistance (R_thJC = 20 °C/W) when mounted on copper heatsink areas.

Key Specifications

Pinout & Package

Supplied in an SO-8 package with internal thermal enhancement: pins 2, 3, 6, and 7 are electrically tied to the die attach flag for improved heat dissipation (R_thJA = 55 °C/W with 6 cm² PCB copper).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with LM78L05ACZ and MCP1700T-5002E/TT, the L78L05ABUTR uniquely balances industrial temperature range, robust fault protection, and predictable bipolar regulator behavior - making it preferred for mission-critical embedded systems where reliability outweighs ultra-low IQ.

Availability

L78L05ABUTR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical sensor nodes, and smart meter communication interfaces requiring stable component supply, long lifecycle support, and guaranteed traceability.

Supply support for L78L05ABUTR 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 silicon solutions for automotive, industrial, and power management applications.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for rugged, cost-effective local regulation in harsh environments - emphasizing fault resilience, wide temperature operation, and minimal external component count.

FAQ

What is the minimum input voltage required for stable 5 V output?

The L78L05ABUTR requires a minimum input voltage of 7 V to maintain regulation at full 100 mA load, based on its 2 V dropout specification. At lighter loads (<40 mA), regulation holds down to ~6.5 V input, but design margin dictates using ≥7 V to ensure stability across temperature and line variation per Table 13 of DS0424 Rev 30.

Can this regulator be used with ceramic output capacitors?

Yes - the L78L05ABUTR is stable with 0.1 µF ceramic output capacitors, as confirmed in Table 13 test conditions and Figure 9 (output characteristics). Unlike older 78xx variants, its internal compensation tolerates low-ESR ceramics without oscillation, simplifying filtering in space-constrained layouts.

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

The SO-8 package (used in L78L05ABUTR) achieves R_thJA = 55 °C/W with 6 cm² copper, versus 200 °C/W for TO-92. This allows continuous 100 mA operation at +70 °C ambient in SO-8, whereas TO-92 derates to ~35 mA under same conditions - making SO-8 essential for high-density or thermally constrained boards.

Is there a recommended input capacitor value and type?

ST specifies a minimum 0.33 µF tantalum or aluminum electrolytic capacitor at the input (CI), placed within 10 mm of the device. For improved high-frequency noise rejection, a parallel 100 nF ceramic capacitor is recommended - especially when the input source has high impedance or long trace inductance, as noted in Figure 3 test circuits.