onsemi MC79L15ABDR2G -15V Fixed Negative Voltage Regulator: Datasheet, Pinout, and Application Circuit Guide
In the realm of analog and mixed-signal circuit design, stable and reliable negative voltage rails are often as crucial as their positive counterparts. The onsemi MC79L15ABDR2G is a quintessential component designed to deliver precisely that: a fixed -15V output. This compact, low-current negative voltage regulator is an industry workhorse, providing simplicity and robustness for a wide array of applications. This guide delves into its datasheet specifications, pinout configuration, and a standard application circuit to ensure successful implementation.
Datasheet Overview and Key Specifications
The MC79L15ABDR2G belongs to the MC79L00 series of fixed negative regulators. Its primary function is to maintain a constant -15V output voltage despite variations in input voltage or load current. Housed in a space-saving SOIC-8 package, it is ideal for PCB designs with strict area constraints.
Key electrical characteristics extracted from the datasheet include:
Output Voltage: -15V ±4% (ensuring consistent regulation)
Output Current: Up to 100 mA (sufficient for low-power circuits)
Input Voltage Range: -18V to -35V (a necessary headroom for proper regulation)
Line Regulation: 60 mV (Typ.) (excellent suppression of input voltage ripple)
Load Regulation: 15 mV (Typ.) (stable output despite changes in current draw)
Peak Current Limit: Internal circuitry provides overcurrent protection
Operating Junction Temperature: 0°C to +125°C
A critical feature of this device is its built-in thermal overload protection, which shuts down the regulator to prevent damage from excessive power dissipation. Internal short-circuit protection further enhances its ruggedness and long-term reliability.
Pinout Configuration
Understanding the pinout is essential for correct wiring. The MC79L15ABDR2G in the SOIC-8 package has a specific pin assignment:
Pin 1 (Input, VIN): This pin receives the unregulated negative input voltage. For a -15V output, a raw DC input of around -18V to -35V is applied here.
Pin 2 (Ground, GND): This is the common ground reference for both the input and output circuits.
Pin 3 (Output, VOUT): The regulated -15V output is delivered from this pin to the load.
The remaining pins (4 through 8) are typically not connected (N/C). Always consult the datasheet for the specific package diagram to avoid assembly errors.
Standard Application Circuit Guide
The typical application circuit for the MC79L15ABDR2G is straightforward, requiring only a few external components for stable operation.
1. Input Capacitor (CIN): A 0.33 μF ceramic or tantalum capacitor should be connected between the Input pin (Pin 1) and ground. This capacitor improves the regulator's stability and its response to transient changes on the input line.
2. Output Capacitor (COUT): A 0.1 μF ceramic capacitor should be connected between the Output pin (Pin 3) and ground. This component is critical for enhancing stability and minimizing output impedance at higher frequencies, ensuring the regulator does not oscillate.
The circuit is implemented as follows:
The raw, unregulated negative DC voltage is fed to Pin 1.
The common ground of the power supply connects to Pin 2.
The load is connected between Pin 3 (VOUT = -15V) and the common ground.
Typical Applications
This regulator is perfectly suited for localized power regulation on PCBs requiring a negative bias voltage. Common use cases include:
Operational amplifier (op-amp) dual supply (±15V) circuits
Sensor interface modules
Audio pre-amplification stages
Low-power analog circuitry requiring a stable negative voltage reference
ICGOODFIND Summary
The onsemi MC79L15ABDR2G is a highly reliable and efficient solution for generating a fixed -15V supply. Its integration of critical protection features like thermal shutdown and current limiting, combined with a minimal external component count, makes it an excellent choice for designers seeking to simplify their power architecture while ensuring performance and durability in low-power, negative voltage applications.
Keywords: Negative Voltage Regulator, Fixed -15V Output, MC79L15ABDR2G, Application Circuit, Low-Current Regulation
