onsemi KA7924

Overview

KA7924 from ON Semiconductor is a fixed-output, three-terminal negative voltage regulator delivering −24 V at up to 1 A output current with ±4% output voltage tolerance, 2 V dropout voltage at 1 A, and integrated thermal overload and short-circuit protection. It serves as the primary negative rail regulator in dual-supply analog circuits, industrial control power stages, and legacy instrumentation requiring stable low-noise DC bias.

For engineers reviewing the KA7924 datasheet, pinout, applications, or equivalent options, key selection considerations include its −24 V fixed output, TO-220 package thermal performance (R_θJA = 65°C/W), ripple rejection of 54–60 dB at 120 Hz, and compatibility with standard 2.2 μF input / 1 μF output capacitor networks per Fairchild/ON Semi design guidelines.

Technical Context

The KA7924 implements a monolithic bipolar linear regulator architecture with internal current limiting, safe operating area (SOA) compensation for the output transistor, and thermal shutdown triggered above junction temperature limits. Its feedback loop uses a precision voltage reference and error amplifier to maintain regulation across line (−27 V to −38 V input) and load (5 mA to 1 A) variations.

Designed for fixed-voltage operation without external components, the KA7924 requires only input and output capacitors for stability-CI ≥ 2.2 μF solid tantalum (or ≥22 μF aluminum) and CO ≥ 1 μF-and supports split-rail configurations when paired with complementary positive regulators like KA7824.

Key Specifications

Pinout & Package

KA7924 is housed in a TO-220 package (JEDEC variation AB) with exposed metal tab electrically connected to Pin 2 (Input). The package provides mechanical mounting via the tab and thermal conduction to an external heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7924CT, KA7924 offers 100 μV lower output noise and 5°C/W lower junction-to-ambient thermal resistance-directly improving signal integrity and thermal headroom. KA7924TU is a packaging variant, not a technical alternative, and provides identical regulation performance.

Availability

KA7924 is available at Aetrix Electronics and suitable for industrial analog signal conditioning, legacy test equipment refurbishment, and dual-rail audio power supply designs requiring stable component supply and long-term obsolescence management.

Supply support for KA7924 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 semiconductor manufacturer specializing in power management, analog, and sensor solutions for industrial, automotive, and cloud infrastructure markets.

The KA79XX series was developed by Fairchild as part of its legacy linear regulator portfolio to provide cost-effective, robust fixed-voltage negative regulation for analog systems-prioritizing reliability, thermal safety, and ease of use in dual-rail applications.

FAQ

What is the maximum input voltage rating for KA7924?

The absolute maximum input voltage for KA7924 is −35 V, as specified in the Absolute Maximum Ratings table. Operation beyond this level risks permanent device damage. For reliable continuous operation, the recommended input range is −27 V to −38 V per the Electrical Characteristics section-note that −38 V is the upper limit of the test condition, not an absolute maximum; sustained operation above −35 V is not advised. Always verify input transient suppression in the final design.

Does KA7924 require external capacitors, and what values are recommended?

Yes, KA7924 requires both input (CI) and output (CO) capacitors for stability and transient response. Per the datasheet: CI ≥ 2.2 μF solid tantalum (or ≥22 μF aluminum electrolytic), placed close to Pin 2 (Input); CO ≥ 1 μF ceramic or tantalum, placed close to Pin 3 (Output). These values prevent oscillation and improve ripple rejection. Failure to include them may cause regulation instability or excessive output noise in the KA7924 circuit.

Can KA7924 be used in parallel to increase output current?

No, KA7924 is not designed for parallel operation. Its internal architecture lacks current-sharing features such as remote sensing or master-slave control. Attempting to parallel multiple KA7924 devices will result in unequal current distribution due to output voltage tolerances (±4%), potentially causing one unit to dominate load current and overheat. For >1 A requirements, select a higher-current regulator or implement an external current-sharing scheme.

What is the thermal shutdown threshold temperature for KA7924?

The KA7924 activates thermal shutdown when the silicon junction temperature exceeds approximately 150°C, as inferred from the Absolute Maximum Ratings (T_J = 150°C) and standard Fairchild bipolar regulator design practice. This threshold is not explicitly published in the datasheet but is consistent across the KA79XX family. Once triggered, the device ceases regulation until junction temperature falls below the hysteresis threshold (~130–140°C), restoring output automatically.

Is KA7924 RoHS compliant and lead-free?

Yes, KA7924 is RoHS compliant and lead-free. As a post-Fairchild-integration ON Semiconductor product, it adheres to ON Semi's global environmental compliance standards, including exemption 7a (Pb in glass frits) where applicable. The TO-220 package uses lead-free matte tin plating on leads and meets JEDEC J-STD-609 Category 2a marking requirements. Full compliance documentation is available via ON Semiconductor's website using the official part number.