Texas Instruments MC79L05CD

Overview

MC79L05CD from Texas Instruments is a fixed negative-voltage linear regulator delivering −5 V output at up to 100 mA, featuring internal thermal-overload protection and short-circuit current limiting in an SOIC-8 package. It operates with input voltages from −7 V to −20 V and maintains ±5% output voltage tolerance across 0°C to 125°C, commonly used for local regulation on analog sensor signal chains and low-power microcontroller supply rails.

For engineers reviewing the MC79L05CD datasheet, MC79L05CD pinout, MC79L05CD application, or MC79L05CD equivalent, key selection considerations include dropout voltage (1.7 V at 40 mA), ripple rejection (41 dB at 120 Hz), bias current (6 mA typical), output noise (40 µV RMS), and thermal impedance (97°C/W in SOIC-D).

Technical Context

This three-terminal negative regulator uses a monolithic bipolar process with internal current limiting and thermal shutdown circuitry. Its architecture eliminates external components while supporting stable operation with only 0.33 µF input and 0.1 µF output capacitors.

The device implements a fixed-output topology with no adjustment terminal-output voltage is set by internal resistor networks. Input regulation is 150 mV over −7 V to −20 V, and load regulation is 30 mV from 1 mA to 40 mA at 25°C.

Key Specifications

Pinout & Package

MC79L05CD is housed in an 8-pin SOIC (D) package per JEDEC MS-012 variation AA, with 1.27 mm lead pitch and maximum height of 1.75 mm. Pin 1 is located at the top-left corner adjacent to the pin-1 identifier marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM79L05ACZ, MC79L05CD offers superior thermal performance (97°C/W vs. 140°C/W) in surface-mount form, while MC79L05ACDR provides identical electrical behavior in optimized packaging for volume manufacturing-neither is pin-compatible with MC79L05CD due to differing pinouts (3-pin vs. 8-pin) and NC pin presence.

Availability

MC79L05CD is available at Aetrix Electronics and suitable for industrial sensor conditioning, legacy microcontroller support, and low-power analog front-ends requiring stable component supply across long-lifecycle programs.

Supply support for MC79L05CD 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

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs for industrial, automotive, and communications markets.

The MC79L00 series was designed specifically for cost-sensitive, low-current negative voltage regulation in space-constrained applications-emphasizing simplicity, reliability, and drop-in replacement capability for legacy discrete solutions.

FAQ

What is the maximum input voltage rating for MC79L05CD?

The absolute maximum input voltage for MC79L05CD is −30 V. Operation beyond this rating risks permanent damage. For reliable regulation, the recommended input range is −7 V to −20 V, ensuring adequate headroom above the 1.7 V dropout while maintaining stability and thermal safety. This range is validated across the full operating temperature span of 0°C to 125°C.

Does MC79L05CD require external capacitors to operate?

Yes, MC79L05CD requires a 0.33 µF capacitor on the input and a 0.1 µF capacitor on the output for stable operation, as specified in the TI SLVS011D datasheet. These values are not optional-they prevent oscillation and ensure proper transient response and ripple rejection. Ceramic capacitors meeting X7R or better dielectric characteristics are recommended for both positions.

What does the "NC" marking mean for pins 4–8 on MC79L05CD?

Pins 4–8 on MC79L05CD are marked "NC" (No internal connection), meaning they have no electrical connection to the silicon die. These pins must not be connected to any net on the PCB-including ground or power planes-as doing so may compromise thermal performance or cause mechanical stress. The SOIC-8 footprint accommodates these unused pins for mechanical robustness and package standardization.

How does MC79L05CD compare to Zener-diode-based negative regulators?

MC79L05CD improves upon Zener-diode + resistor solutions by providing two orders of magnitude lower output impedance, 40 µV RMS noise (vs. >100 µV for Zener), and built-in thermal/short-circuit protection. It also eliminates bias current dependency on load, enabling consistent −5 V regulation across 1–100 mA without recalculating resistor values-making it ideal for production designs where repeatability matters.

Is MC79L05CD RoHS compliant and lead-free?

Yes, MC79L05CD is RoHS compliant and lead-free, with a green (RoHS & no Sb/Br) eco plan and NIPDAU lead finish. It meets JEDEC MSL Level-1 moisture sensitivity classification and is rated for reflow peak temperatures up to 260°C. The device marking "79L05A" appears on the top surface, and full compliance documentation is available via Texas Instruments' official product folder.