onsemi MC78L09ABDR2

Overview

MC78L09ABDR2 from onsemi is a 100 mA, fixed +9.0 V positive linear voltage regulator in SOIC-8 package, featuring internal short-circuit current limiting, thermal shutdown, and no external components required for basic operation. It operates across −40°C to +125°C, delivers ±5% output voltage accuracy at 25°C (8.6–9.4 V), and maintains regulation with ≥2.0 V input-to-output differential.

For engineers reviewing the MC78L09ABDR2 datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (1.7 V typ), ripple rejection (37–57 dB), load regulation (≤40 mV over 1–40 mA), and thermal resistance (R_JA dependent on PCB copper area per Figure 8).

Technical Context

The MC78L09ABDR2 implements a monolithic series-pass transistor regulator architecture with built-in protection circuitry: thermal overload shutdown triggers at ~150°C junction temperature, and foldback current limiting activates during output short circuits. Its internal reference and error amplifier maintain stable output despite line (11.5–24 V input) and load (1–100 mA) variations.

Designed for low-power embedded systems, it requires only input (C_IN = 0.33 µF) and optional output (C_OUT = 0.1 µF) capacitors for stability and transient response enhancement. The SOIC-8 package features internally commoned pins 2/3/6/7 tied to the die attach flag, reducing thermal resistance versus standard SO-8.

Key Specifications

Pinout & Package

MC78L09ABDR2 uses the SOIC-8 (Case 751) package with 1.27 mm pitch. Pins 2, 3, 6, and 7 are electrically common to the die attach flag, enabling enhanced thermal dissipation when mounted on adequate PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L09ACDR2G, the MC78L09ABDR2 offers extended low-temperature capability critical for cold-climate deployment; versus NCV78L09ABDR2G, it provides identical performance at lower cost where automotive certification is unnecessary.

Availability

MC78L09ABDR2 is available at Aetrix Electronics and suitable for industrial sensor interfaces, automotive body electronics, low-power IoT nodes, and legacy equipment retrofits requiring stable component supply across extended temperature ranges.

Supply support for MC78L09ABDR2 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MC78L00A Series was designed as a cost-effective, rugged fixed-output linear regulator family for general-purpose DC power conditioning in space- and reliability-constrained applications.

FAQ

What is the maximum input voltage for the MC78L09ABDR2?

The absolute maximum input voltage for the MC78L09ABDR2 is 35 V DC for devices rated at 12–18 V output (per Absolute Maximum Ratings table). Since MC78L09ABDR2 is a 9 V device, its VI(max) is 30 V - confirmed in the "Input Voltage (5.0 V–9.0 V)" row of the Absolute Maximum Ratings section. Exceeding this risks permanent damage. Always maintain ≥2.0 V headroom above 9.0 V output for regulation.

Does the MC78L09ABDR2 require an output capacitor for stability?

No, the MC78L09ABDR2 does not require an output capacitor for stability - the datasheet explicitly states "CO is not needed for stability" in Figure 2. However, adding a 0.1 µF ceramic or tantalum capacitor improves transient response during load steps. This design flexibility reduces BOM count in static-load applications while allowing optimization for dynamic performance where needed.

How many ground pins does the MC78L09ABDR2 SOIC-8 package have, and why?

The MC78L09ABDR2 SOIC-8 package has five ground terminals: Pins 2, 3, 5, 6, and 7. Per the datasheet, Pins 2, 3, 6, and 7 are electrically common to the die attach flag, forming a low-thermal-resistance path to the PCB. Pin 5 is also grounded. This multi-pin grounding reduces both electrical impedance and thermal resistance (R_JA), enabling higher power dissipation than standard SO-8 packages without heatsinking.

Can the MC78L09ABDR2 be used in automotive applications?

Yes - the "AB" suffix in MC78L09ABDR2 denotes operation from −40°C to +125°C, meeting extended temperature requirements for many automotive subsystems. For full automotive qualification (AEC-Q100, PPAP), the NCV78L09ABDR2G variant is specified. The MC78L09ABDR2 itself is widely deployed in non-safety-critical automotive modules such as lighting controls and infotainment peripherals where extended temp range suffices.

What is the typical dropout voltage of the MC78L09ABDR2, and how does it affect system design?

The typical dropout voltage of the MC78L09ABDR2 is 1.7 V at 25°C and 40 mA load (per Electrical Characteristics table for MC78L09AC/AB). This means the input must be ≥10.7 V to sustain 9.0 V output under full load. Designers must ensure upstream supply (e.g., 12 V battery or SMPS) maintains ≥10.7 V under worst-case ripple and load conditions - especially during cold cranking or brown-out events.