STMicroelectronics L79L15ACUTR

Overview

L79L15ACUTR from STMicroelectronics is a fixed-output, three-terminal negative linear voltage regulator delivering -15 V at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components and is specified for operation from -40 °C to +125 °C junction temperature, with ±4% output tolerance and 1.7 V dropout voltage - used in local on-card regulation for noise-sensitive analog and mixed-signal circuits.

For engineers reviewing the L79L15ACUTR datasheet, L79L15ACUTR pinout, L79L15ACUTR application, or L79L15ACUTR equivalent, key selection criteria include guaranteed -15 V output stability under load variation, low quiescent current (6.5 mA typ. at 25 °C), high PSRR (34–39 dB at 120 Hz), and TO-92 package thermal performance with R_thJA = 200 °C/W (unheatsinked).

Technical Context

The L79L15ACUTR implements a monolithic PNP pass transistor architecture with built-in thermal overload and short-circuit foldback protection. Its internal reference and error amplifier maintain output regulation across input voltages from -17.5 V to -30 V and load currents from 1 mA to 100 mA.

Designed as a direct replacement for Zener diode–resistor networks, it delivers two orders-of-magnitude lower output impedance, reduced noise (90 µV RMS, 10 Hz–100 kHz), and tighter line/load regulation (max. 250 mV line, 150 mV load) compared to passive solutions.

Key Specifications

Pinout & Package

Supplied in TO-92 plastic package (ECOPACK® compliant), with 3 leads: Input (pin 1), Ground (pin 2), Output (pin 3). Pin identification is standardized per Figure 2 (top view) in ST DocID2511 Rev 19: lead 1 is leftmost when flat side faces user and leads point downward.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7915CDT/NOPB and MC79L15ACDR2G, the L79L15ACUTR offers lowest assembly cost and simplest layout in legacy designs, while trading off thermal headroom and mounting flexibility - optimal for cost-sensitive, low-to-medium volume industrial controls with moderate ambient temperatures.

Availability

L79L15ACUTR is available at Aetrix Electronics and suitable for industrial sensor interfaces, RS-232 transceivers, and analog front-end subsystems requiring stable component supply with long-term manufacturability and ECOPACK® compliance.

Supply support for L79L15ACUTR 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local regulation in noise-sensitive analog circuits - emphasizing reliability, ease of use, and compatibility with legacy Zener-based designs.

FAQ

What is the minimum input voltage required for L79L15ACUTR to maintain regulation?

The L79L15ACUTR requires a minimum input voltage of -16.7 V (i.e., |V_IN| ≥ |V_OUT| + V_DROP = 15 V + 1.7 V) to sustain regulation at full 100 mA load and 25 °C ambient. At higher temperatures or lighter loads, regulation holds down to -17.5 V per Table 6 in ST DocID2511 Rev 19.

Can L79L15ACUTR be used in parallel to increase output current?

No - the L79L15ACUTR lacks current-sharing capability and has no provision for master-slave or ballast resistor configuration. Parallel connection risks thermal runaway due to mismatched output voltages and unequal current division; ST does not recommend or characterize this configuration.

Is an input capacitor required for stable operation?

An input capacitor (C_I = 0.33 µF ceramic) is recommended per the datasheet test circuit to suppress high-frequency noise and prevent oscillation when the regulator is located far from the bulk input capacitor. While not strictly mandatory for basic functionality, omission may degrade PSRR and transient response in noisy environments.

Does L79L15ACUTR support reverse-voltage protection?

No - the L79L15ACUTR has no internal reverse-polarity protection. Applying positive voltage to the input or grounding the input while output is driven negative can cause irreversible damage. External series diode or MOSFET-based protection must be added if reverse-input conditions are possible in the system.