Texas Instruments LM78L15ACM

Overview

LM78L15ACM from Texas Instruments is a 15 V, 100 mA fixed-output linear voltage regulator in SOIC-8 package, featuring ±5% output voltage tolerance over temperature, internal thermal overload and short-circuit protection, and no external components required. It delivers stable local regulation for low-power analog and digital circuits where input voltage ranges up to 30 V.

For engineers reviewing the LM78L15ACM datasheet, LM78L15ACM pinout, LM78L15ACM application, or LM78L15ACM equivalent, key selection factors include dropout voltage (1.7 V at 100 mA), ripple rejection (37–51 dB at 120 Hz), load regulation (≤150 mV over 1–100 mA), and SOIC-8 thermal performance (R_θJA = 128.8°C/W).

Technical Context

The LM78L15ACM implements a three-terminal monolithic series pass regulator architecture with built-in safe-area protection for the output transistor, ensuring robust operation under transient overloads. Its internal reference and error amplifier maintain 15 V output with ≤±5% tolerance across 0°C to 125°C junction temperature.

It operates in normal mode by sourcing current from VIN to VOUT while sinking ground current through GND; shutdown activates automatically during thermal overload (>125°C) or sustained short-circuit conditions. No external feedback network is needed-output is fixed and internally trimmed.

Key Specifications

Pinout & Package

LM78L15ACM uses the SOIC-8 (D) package, 3.90 mm × 4.90 mm body size, with exposed pad not present. Pin functions are defined per TI's official pin configuration: Pins 1 and 8 are VOUT; pins 2, 3, 6, and 7 are GND; pins 4 and 5 are NC (no connection). This layout supports dual ground paths and improved thermal dissipation versus TO-92.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L15ACM, LM78L15ACZ trades thermal efficiency for mechanical simplicity in through-hole designs, while MC78L15ACDR2G offers identical SOIC-8 performance with broader temperature certification-enabling drop-in substitution where AEC-Q100 compliance matters.

Availability

LM78L15ACM is available at Aetrix Electronics and suitable for battery chargers, portable instrumentation, LED lighting, and low wattage power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LM78L15ACM 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, delivering analog and embedded processing solutions for industrial, automotive, and consumer markets since 1930.

The LM78Lxx series was designed as a low-cost, low-power replacement for Zener-diode regulators-targeting space-constrained, cost-sensitive applications needing reliable fixed-voltage rails without external components.

FAQ

What is the maximum input voltage for LM78L15ACM?

The LM78L15ACM supports a maximum continuous input voltage of 30 V, with an absolute maximum rating of 35 V. Exceeding 30 V risks exceeding safe operating area limits and triggering thermal shutdown. For reliable operation, maintain VIN ≤30 V and ensure sufficient headroom above 16.7 V minimum input to sustain regulation at full load.

Does LM78L15ACM require external capacitors?

Yes, LM78L15ACM requires at least a 0.01 µF ceramic capacitor on the VOUT pin to suppress high-frequency noise, and a 0.33 µF capacitor on VIN if placed >3 inches from the main power filter. These are mandatory for stability and noise control-TI specifies them as "recommended minimum" and "required" respectively in the datasheet.

What is the thermal resistance (RθJA) of LM78L15ACM?

The LM78L15ACM in SOIC-8 (D) package has a junction-to-ambient thermal resistance (R_θJA) of 128.8°C/W. This value assumes standard JEDEC 2-layer board conditions. Actual thermal performance depends on PCB copper area, airflow, and nearby heat sources-derating is required above 85°C ambient.

Can LM78L15ACM be used in adjustable-output configurations?

Yes, LM78L15ACM can be configured as an adjustable regulator by connecting its GND pin to the center of a resistive divider between VOUT and ground, using the 15 V internal reference as a基准. However, this modifies load regulation and line regulation performance-TI provides design equations and stability guidelines in Figure 10 of the datasheet.

Is LM78L15ACM pin-compatible with other LM78Lxx variants?

Yes, all LM78Lxx devices-including LM78L15ACM, LM78L12ACM, and LM78L05ACM-share identical SOIC-8 pinouts: VOUT on pins 1/8, GND on pins 2/3/6/7, and NC on pins 4/5. This allows direct substitution in existing layouts when only output voltage differs, provided thermal and input voltage margins are verified.