onsemi KA7912

Overview

KA7912ATU from ON Semiconductor is a fixed-output, three-terminal negative voltage regulator delivering −12 V at up to 1 A, featuring internal thermal overload protection, short-circuit current limiting, and safe operating area compensation. It operates across 0°C to +125°C and is used in dual-rail power supplies, industrial control logic, and analog signal conditioning circuits requiring stable negative bias.

For engineers reviewing the KA7912ATU datasheet, pinout, applications, or equivalent options, this page provides verified specifications, TO-220 package layout, real-world use cases, and validated alternative parts for design-in and supply continuity planning.

Technical Context

The KA7912ATU implements a monolithic bipolar linear regulator architecture with an internal pass transistor, error amplifier, reference voltage, and protection circuitry. Its output voltage is trimmed to ±2% tolerance at 25°C and maintains regulation under load currents from 5 mA to 1 A with input voltages between −15.5 V and −27 V.

It delivers 2 V dropout at 1 A and achieves 54–60 dB ripple rejection at 120 Hz. Thermal shutdown activates at junction temperatures exceeding safe limits, and short-circuit current is limited to 300 mA under −35 V input stress.

Key Specifications

Pinout & Package

KA7912ATU is housed in a TO-220 package with standard 3-lead JEDEC variation AB footprint. The case is electrically connected to Pin 1 (GND), enabling direct mounting to a heatsink without isolation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with KA7912ATU, LM7912CT offers slightly better thermal performance but looser output accuracy, while KA7912TU matches the original KA79XX family tolerance-making both viable alternatives depending on whether precision or legacy compatibility drives the selection.

Availability

KA7912ATU is available at Aetrix Electronics and suitable for industrial control systems, test instrumentation, and audio electronics requiring stable component supply with guaranteed long-term manufacturability.

Supply support for KA7912ATU 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global leader in energy-efficient semiconductor solutions, serving automotive, industrial, cloud computing, and consumer markets with high-reliability components.

The KA79XXA series was developed to provide enhanced-output-accuracy replacements for legacy 79xx regulators, targeting applications demanding tighter voltage stability in negative power rails without redesigning PCB layouts.

FAQ

What is the output voltage tolerance of KA7912ATU?

The KA7912ATU has a guaranteed output voltage tolerance of ±2% at +25°C, with a full-range specification of −11.5 V to −12.5 V across 0°C to +125°C junction temperature and 5 mA to 1 A load. This tighter tolerance versus standard KA7912 (±4%) improves system-level accuracy in precision analog circuits where reference stability is critical. The KA7912ATU maintains this spec without external trimming components.

Can KA7912ATU replace LM7912 in existing designs?

Yes, KA7912ATU is pin-compatible with LM7912 and shares identical TO-220 pinout (GND–Input–Output), same absolute maximum ratings, and overlapping electrical characteristics. Its ±2% tolerance and identical 2 V dropout make it a functional upgrade-especially where improved output accuracy is beneficial. No PCB changes are required, though thermal validation is recommended due to minor R_θJA differences.

What input voltage range must be applied to KA7912ATU?

KA7912ATU requires an input voltage between −15.5 V and −27 V for guaranteed regulation across full load and temperature. The absolute maximum input is −35 V. Operation below −14.5 V risks dropout, while exceeding −35 V may cause permanent damage. For reliable 1 A output, a −19 V nominal input (as specified in the datasheet test condition) provides optimal headroom and thermal margin.

Does KA7912ATU require external capacitors?

Yes, KA7912ATU requires a minimum 2.2 μF input capacitor (CI) and 1 μF output capacitor (CO) for stability, per the datasheet. CI must be solid tantalum if using the specified value; aluminum electrolytic types require ≥10× capacitance. CO improves transient response and prevents oscillation-critical when driving capacitive loads like op-amp inputs or ADC reference buffers in the KA7912ATU application.

How does KA7912ATU handle thermal overload?

KA7912ATU integrates thermal shutdown that disables the output when junction temperature exceeds safe limits, typically around 150°C. Once the die cools below the hysteresis threshold (~130°C), regulation resumes automatically. This protection is independent of load current and works even during sustained short-circuit conditions. The TO-220 package's 5°C/W junction-to-case thermal resistance enables effective heatsinking to sustain 1 A continuous output in the KA7912ATU application.