onsemi KA79M15

Overview

KA79M15 from Fairchild Semiconductor is a fixed-output, 3-terminal, medium-current negative voltage regulator delivering −15 V ±3% at up to 500 mA load current, with internal thermal overload protection, short-circuit current limiting, and safe-area compensation. It operates across an input range of −17.5 V to −30 V and is used in industrial power supplies, analog instrumentation, and dual-rail op-amp biasing.

For engineers reviewing the KA79M15 datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed −15 V output tolerance over temperature and load, 1.1 V dropout voltage at 500 mA, 59 dB ripple rejection at 120 Hz, and TO-220/D-PAK package compatibility for thermal management in regulated DC systems.

Technical Context

The KA79M15 employs monolithic IC architecture with built-in current limiting, thermal shutdown, and output transistor safe-area compensation-enabling robust operation without external protection circuitry. Its regulation loop maintains stable −15 V output under line variations (−17.5 V to −30 V) and load changes (5 mA to 500 mA).

It achieves 54–59 dB ripple rejection at 120 Hz with specified input capacitor (0.33 µF) and output capacitor (0.1 µF), and exhibits −1.0 mV/°C output voltage drift over temperature with 5 mA load-critical for precision analog subsystems requiring stable negative rail integrity.

Key Specifications

Pinout & Package

KA79M15 is available in TO-220 and D-PAK packages. Both use identical 3-pin terminal assignment: Pin 1 = Ground, Pin 2 = Input (negative supply), Pin 3 = Output (regulated −15 V).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7915CDT/NOPB, KA79M15 offers superior safe-area compensation and 9 dB higher ripple rejection; versus MC7915BD2TR4, it trades extended temperature range for lower cost and legacy design compatibility in 0–+125 °C industrial settings.

Availability

KA79M15 is available at Aetrix Electronics and suitable for industrial power supplies, analog instrumentation, audio signal processing, and legacy control systems requiring stable component supply with long-term lifecycle visibility.

Supply support for KA79M15 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete solutions before its acquisition by ON Semiconductor in 2016.

The KA79MXX series was designed as cost-effective, robust negative linear regulators for industrial and instrumentation applications where simplicity, reliability, and thermal resilience are prioritized over ultra-low quiescent current or wide temperature range.

FAQ

What is the maximum input voltage rating for KA79M15?

The KA79M15 has an absolute maximum input voltage of −40 V for the −24 V version variant, but for the KA79M15 specifically, the rated maximum input is −35 V. Operation beyond −35 V risks permanent damage even with brief transients. The recommended operating input range is −17.5 V to −30 V to ensure regulation stability and thermal safety within the 5 °C/W junction-to-case thermal resistance limit.

Does KA79M15 require external capacitors, and if so, what values are mandatory?

Yes, KA79M15 requires two external capacitors: a 0.33 µF input capacitor (solid tantalum preferred) and a 0.1 µF output capacitor (ceramic or tantalum). These are mandatory for stability per the datasheet test circuit and Figure 1. Omitting either capacitor may cause oscillation or poor transient response. Aluminum electrolytic substitutes are permitted only for the input capacitor (25 µF minimum), but not for the output.

Can KA79M15 be used in surface-mount designs?

Yes-KA79M15 is offered in both through-hole TO-220 and surface-mount D-PAK packages. The D-PAK variant (e.g., KA79M15R) uses the same pinout (Pin 1 = GND, Pin 2 = Input, Pin 3 = Output) and shares identical electrical specifications. Thermal design must account for D-PAK's higher junction-to-air thermal resistance (65 °C/W) versus TO-220's 5 °C/W case-to-heatsink path.

What is the short-circuit behavior of KA79M15?

KA79M15 features internal short-circuit current limiting that clamps output current to approximately 140 mA when the output is shorted to ground. This protects the device during fault conditions without requiring external current-limiting resistors. The part remains functional after fault removal and does not latch off-thermal shutdown activates only if sustained short-circuit causes junction temperature to exceed safe limits.

How does KA79M15 compare to LM7915 in terms of thermal performance?

KA79M15 specifies a junction-to-case thermal resistance of 5 °C/W in TO-220, matching LM7915's typical value. However, KA79M15 includes output transistor safe-area compensation, which improves thermal survivability during dynamic overloads-where LM7915 may suffer secondary breakdown. Both require heatsinking above ~1.5 W dissipation, but KA79M15 sustains higher peak currents (650 mA) without failure.