STMicroelectronics L79L05ABZ

Overview

L79L05ABZ from STMicroelectronics is a three-terminal fixed negative linear voltage regulator delivering -5 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components and operates across an input voltage range of -7 V to -20 V, with ±2% output voltage tolerance (±0.1 V) at 25°C - ideal for local on-card regulation in industrial control and embedded power subsystems.

For engineers reviewing the L79L05ABZ datasheet, L79L05ABZ pinout, L79L05ABZ application, or L79L05ABZ equivalent, this device serves as a robust replacement for Zener diode/resistor regulators in low-noise, space-constrained negative rail applications where quiescent current (6 mA typ.), dropout voltage (1.7 V), and supply voltage rejection (41–49 dB) are critical selection criteria.

Technical Context

The L79L05ABZ implements a monolithic bipolar linear regulator architecture with built-in thermal shutdown and foldback current limiting. Its output voltage is stabilized via internal bandgap reference and error amplifier feedback, achieving load regulation of ≤30 mV (1–40 mA) and line regulation of ≤100 mV (-8 to -20 V).

Designed for operation over -40°C to +125°C junction temperature, it maintains output noise of 40 µV_RMS (10 Hz–100 kHz) and SVR ≥41 dB at 120 Hz - enabling use in analog signal chains and mixed-signal boards where clean negative bias rails are required.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-pin plastic transistor outline), with lead-free finish and JEDEC-standard mechanical dimensions (D = 4.45–4.95 mm, E = 3.30–3.94 mm, L = 12.7–15.49 mm). The package provides adequate thermal dissipation for 100 mA operation with minimal PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM79L05ACZ and MC79L05CP, the L79L05ABZ offers superior output accuracy, extended industrial temperature range (-40°C to +125°C), and lower quiescent current - making it the preferred choice for new designs requiring reliability under thermal stress or precision analog performance.

Availability

L79L05ABZ is available at Aetrix Electronics and suitable for industrial automation, embedded sensor nodes, and RS-232 interface modules requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for L79L05ABZ 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, specializing in power management, analog, microcontrollers, and automotive ICs.

The L79L00 series belongs to ST's legacy linear regulator product line, designed specifically for cost-effective, robust local regulation in industrial, telecom, and consumer equipment where simplicity, reliability, and wide temperature operation are essential.

FAQ

What is the minimum input voltage required for L79L05ABZ to maintain regulation?

The L79L05ABZ requires a minimum input voltage of -7 V to sustain -5 V output regulation under all load and temperature conditions. This 2 V headroom accommodates its 1.7 V dropout voltage plus margin for line transients and thermal derating. Operation below -7 V risks loss of regulation and increased output ripple.

Can L79L05ABZ be used in parallel to increase output current?

No - L79L05ABZ is not designed for parallel operation. Its output voltage tolerance (±2%) and lack of current-sharing features mean mismatched units would cause one device to dominate conduction, leading to thermal imbalance and premature failure. For >100 mA, use a higher-current regulator or external pass transistor configuration.

Does L79L05ABZ require input or output capacitors for stability?

No external capacitors are required for basic stability per STMicroelectronics' datasheet. However, a 0.33 µF ceramic input capacitor and 0.1 µF ceramic output capacitor are recommended for optimal transient response and high-frequency noise suppression - especially in noisy environments or when driving capacitive loads.

How does the AB grade differ from AC or C grades in the L79L05 family?

The AB grade (e.g., L79L05ABZ) specifies operation from -40°C to +125°C junction temperature and ±2% output voltage tolerance. In contrast, AC grade supports 0°C to +125°C with ±2%, and C grade supports 0°C to +125°C with ±5%. The AB grade is uniquely qualified for extended industrial and automotive under-hood applications.