STMicroelectronics L79L08ACZ-AP

Overview

L79L08ACZ-AP from STMicroelectronics is a fixed -8 V, 100 mA negative linear voltage regulator in TO-92 package, featuring thermal overload and short-circuit protection, no external components required, and 40 mA load capability at ±5% output tolerance-used for local regulation on industrial control PCBs to suppress supply noise and improve rail stability.

For engineers reviewing the L79L08ACZ-AP datasheet, L79L08ACZ-AP pinout, L79L08ACZ-AP application, or L79L08ACZ-AP equivalent, key selection criteria include dropout voltage (1.7 V), output noise (60 µV RMS), supply voltage rejection (37–45 dB), quiescent current (6 mA at 25 °C), and operating junction temperature range (0 to 125 °C).

Technical Context

The L79L08ACZ-AP implements a monolithic PNP pass transistor with internal current limiting and thermal shutdown, delivering regulated -8 V output without external capacitors beyond minimum 0.33 µF input and 0.1 µF output bypass. It operates across input voltages from -10.5 V to -23 V and maintains regulation under 100 mA load.

Its design targets low-noise local regulation where Zener/resistor alternatives fail-offering two orders-of-magnitude lower output impedance, reduced quiescent current, and improved line/load regulation (125 mV and 40 mV respectively) over discrete solutions.

Key Specifications

Pinout & Package

Package: TO-92 (plastic, 3-lead, through-hole). Pin configuration verified per Figure 2 (top view) in ST DocID2511 Rev 18: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7908ACZ and MC79L08ACPR, the L79L08ACZ-AP offers optimal balance of cost, noise performance (60 µV), and thermal robustness (0–125 °C operation) for industrial-grade local regulation where ±5% tolerance is sufficient.

Availability

L79L08ACZ-AP is available at Aetrix Electronics and suitable for industrial sensor interfaces, legacy RS-232 communication modules, and audio preamplifier bias circuits requiring stable component supply and long-term obsolescence management.

Supply support for L79L08ACZ-AP 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 analog components for industrial, automotive, and consumer markets.

The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications needing reliable fixed negative voltage regulation without external components.

FAQ

What is the minimum input voltage required for L79L08ACZ-AP to maintain regulation?

The L79L08ACZ-AP requires a minimum input voltage of -9.7 V (i.e., |VI| ≥ |VO| + Vd = 8 V + 1.7 V) to sustain regulation under full 100 mA load. At lighter loads (≤40 mA), it remains in regulation down to -10.5 V per Table 4, with guaranteed performance across -10.5 V to -23 V.

Can L79L08ACZ-AP be used in parallel to increase output current?

No-L79L08ACZ-AP is not designed for parallel operation. Its output voltage tolerance (±5%) and lack of current-sharing features (e.g., current-limit matching or thermal coupling) make paralleling unreliable and potentially unstable. For >100 mA, use a higher-current regulator like L79M08 or add an external pass transistor.

Does L79L08ACZ-AP require input and output capacitors?

Yes-ST specifies a minimum 0.33 µF ceramic capacitor at the input and 0.1 µF ceramic capacitor at the output for stability and transient response. Omitting either risks oscillation or degraded load/line regulation, especially under dynamic load conditions or long PCB traces.

Is L79L08ACZ-AP RoHS-compliant and halogen-free?

Yes-per ST's ECOPACK® documentation in Section 5 of DocID2511 Rev 18, the L79L08ACZ-AP in TO-92 package meets RoHS Directive 2011/65/EU and is halogen-free, with lead-free terminations and compliant molding compounds verified per ST's environmental specifications.