onsemi KA78L12AMTF

Overview

KA78L12AMTF from Fairchild Semiconductor is a fixed-output, 3-terminal, monolithic positive voltage regulator delivering 12 V ±5% at up to 100 mA. It features thermal overload protection, short-circuit current limiting, and a dropout voltage of 1.7 V at 25°C. It operates across 0°C to +125°C and is used in low-power microcontroller supply rails, sensor interface circuitry, and industrial control logic.

For engineers reviewing the KA78L12AMTF datasheet, pinout, applications, or equivalent options, key selection criteria include output tolerance (±5%), thermal resistance (225°C/W), ripple rejection (37–65 dB), quiescent current (2.1–6.0 mA), and SOT-89 package compatibility with space-constrained PCB layouts.

Technical Context

The KA78L12AMTF implements a classic series-pass linear regulation architecture with internal reference, error amplifier, and pass transistor. Its block diagram includes short-circuit protection and thermal shutdown circuits that activate independently without latch-up.

It requires external input (0.33 μF) and output (0.1 μF) ceramic capacitors for stability and transient response. Input voltage range is 14.5 V to 27 V for guaranteed 12 V output under load, with absolute maximum input rated at 35 V.

Key Specifications

Pinout & Package

SOT-89 package: 3-pin surface-mount, single-ended, thermally enhanced plastic case with exposed tab (pin 2 is GND and thermal pad).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar positive linear regulator applications.

Compared with MC78L12ACZTG and LM78L12ACZ, the KA78L12AMTF offers superior thermal performance in SOT-89 for high-density layouts, lower quiescent current than LM78L12ACZ, and tighter production consistency due to Fairchild's modern process control - making it optimal for volume industrial PCBs requiring reliability and space efficiency.

Availability

KA78L12AMTF is available at Aetrix Electronics and suitable for industrial control systems, sensor interface modules, and embedded microcontroller power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for KA78L12AMTF 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 components before its acquisition by ON Semiconductor in 2016.

The KA78LXXA series was designed as a cost-optimized, thermally robust family of 100 mA linear regulators targeting industrial, automotive, and consumer applications where simplicity, reliability, and wide operating temperature range were essential.

FAQ

What is the maximum input voltage for KA78L12AMTF?

The KA78L12AMTF supports a maximum input voltage of 35 V under absolute ratings. For reliable continuous operation with 12 V output, the recommended input range is 14.5 V to 27 V. Exceeding 27 V increases power dissipation and thermal stress, especially given its 225°C/W junction-to-air thermal resistance in the SOT-89 package. Always verify power dissipation (P_D = (V_IN − V_OUT) × I_OUT) stays below 0.75 W.

Does KA78L12AMTF require external capacitors?

Yes, KA78L12AMTF requires two external capacitors: a 0.33 μF ceramic capacitor between input and ground, and a 0.1 μF ceramic capacitor between output and ground. These are mandatory for stability and transient response, as specified in the datasheet's Typical Application (Figure 2). The device is optimized for low-ESR ceramics and does not require tantalum or electrolytic types.

Is KA78L12AMTF pin-compatible with other 78Lxx regulators?

KA78L12AMTF uses the standard SOT-89 pinout (Input–GND–Output), matching industry-standard 78Lxx SOT-89 variants including MC78L12ACZTG (TO-92) and LM78L12ACZ (TO-92) in functional assignment - though physical package differs. No PCB redesign is needed when replacing other SOT-89 78L12 parts, but thermal layout must accommodate its 225°C/W R_θJA.

What is the output voltage tolerance of KA78L12AMTF over temperature?

The KA78L12AMTF guarantees ±5% output voltage tolerance (11.4–12.6 V) across its full operating temperature range of 0°C to +125°C and load range of 1 mA to 70 mA. At 25°C, typical output is 12.0 V with min/max of 11.5 V and 12.5 V. Temperature coefficient is −1.0 mV/°C, contributing predictably to drift within the overall tolerance band.

Can KA78L12AMTF be used in automotive applications?

KA78L12AMTF is rated for 0°C to +125°C operation and includes thermal shutdown and short-circuit protection - features aligned with under-hood automotive requirements. However, it is not AEC-Q100 qualified. For production automotive use, consult Fairchild/ON Semiconductor for qualified alternatives; KA78L12AMTF remains suitable for non-safety-critical aftermarket or industrial-adjacent vehicle systems with validated thermal design.