KA7924 Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The KA7924 is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed negative output of -24V at 1A in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and component sourcing. The KA7924 serves applications requiring stable negative voltage regulation with integrated over-temperature and short-circuit protection.

Key Parameters

Parameter	Value
Output Configuration	Negative
Output Type	Fixed
Output Voltage	-24V
Output Current	1A
Input Voltage (Max)	-35V
Dropout Voltage	2V @ 1A (Typ)
Quiescent Current	6 mA
PSRR	60dB (120Hz)
Package	TO-220-3
Operating Temperature	0°C ~ 125°C
Protection Features	Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution for the KA7924 is determined by strict alignment of electrical and mechanical parameters. All substitute parts must maintain the following critical specifications:

Output voltage: -24V fixed
Output current capability: 1A minimum
Package type: TO-220-3 (through-hole mounting)
Output configuration: Negative
Protection features: Over-temperature and short-circuit protection

The substitute parts are grouped into two categories based on parameter matching:

Direct Substitutes (MC7924BTG, MC7924CTG): These parts share identical output voltage, current rating, and package configuration. They differ in input voltage rating (-40V vs -35V) and dropout voltage (1.3V vs 2V), representing improved electrical performance characteristics.

Parametric Equivalent (KA7924TU): This part maintains identical electrical specifications and package type, with the primary difference being manufacturer (Fairchild Semiconductor vs onsemi) and product status (Active vs Obsolete).

Parameter Comparison

Parameter	KA7924	MC7924BTG	MC7924CTG	KA7924TU
Manufacturer	onsemi	onsemi	onsemi	Fairchild Semiconductor
Output Voltage	-24V	-24V	-24V	-24V
Output Current	1A	1A	1A	1A
Input Voltage (Max)	-35V	-40V	-40V	-35V
Dropout Voltage	2V @ 1A	1.3V @ 1A	1.3V @ 1A	2V @ 1A
Quiescent Current	6 mA	Not specified	Not specified	6 mA
PSRR	60dB (120Hz)	56dB (120Hz)	56dB (120Hz)	60dB (120Hz)
Package	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Operating Temperature	0°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C
Product Status	Obsolete	Obsolete	Obsolete	Active
Protection Features	Over Temperature, Short Circuit	Over Current, Over Temperature	Over Current, Over Temperature	Over Temperature, Short Circuit

Engineering Selection Recommendations

KA7924TU (Fairchild Semiconductor): This part is the preferred substitute due to its Active product status, ensuring long-term availability and continued manufacturer support. It provides identical electrical specifications and package configuration to the original KA7924, with RoHS3 compliance and higher inventory availability (17,300 units). This option is suitable for new designs and ongoing production requiring component continuity.

MC7924CTG (onsemi): This substitute offers improved input voltage tolerance (-40V vs -35V) and lower dropout voltage (1.3V vs 2V), representing enhanced electrical performance. Operating temperature range matches the original (0°C ~ 125°C). RoHS3 compliance and substantial inventory (5,100 units) support production requirements. This option is appropriate for applications benefiting from extended input voltage headroom.

MC7924BTG (onsemi): This substitute provides the same electrical improvements as MC7924CTG but with extended operating temperature range (-40°C ~ 125°C). This option is suitable for applications requiring operation at temperatures below 0°C. Lower inventory availability (646 units) may impact sourcing for high-volume production.

Frequently Asked Questions (FAQ)

Q: Can MC7924BTG and MC7924CTG be used interchangeably with KA7924?

A: Both parts are direct substitutes with identical output voltage (-24V), current rating (1A), and TO-220-3 package. The primary differences are improved dropout voltage (1.3V vs 2V) and extended input voltage rating (-40V vs -35V). MC7924BTG additionally supports operation from -40°C, while MC7924CTG maintains the original 0°C lower temperature limit. Selection depends on specific application temperature and input voltage requirements.

Q: What is the advantage of KA7924TU over the original KA7924?

A: KA7924TU maintains identical electrical specifications and package type but offers Active product status, ensuring ongoing manufacturer support and availability. It is manufactured by Fairchild Semiconductor and carries RoHS3 compliance. For applications requiring component continuity and long-term sourcing stability, KA7924TU is the recommended choice.

Q: Are all substitute parts available in the same TO-220-3 package?

A: Yes. All substitute parts (MC7924BTG, MC7924CTG, and KA7924TU) are packaged in TO-220-3, ensuring mechanical and thermal compatibility with the original KA7924 without PCB redesign.

Q: What protection features do the substitute parts provide?

A: MC7924BTG and MC7924CTG provide over-current and over-temperature protection. KA7924TU provides over-temperature and short-circuit protection, matching the original KA7924. All parts include integrated thermal protection suitable for standard linear regulator applications.

Q: Which substitute part has the best availability?

A: KA7924TU has the highest inventory (17,300 units), followed by MC7924CTG (5,100 units) and MC7924BTG (646 units). For high-volume production, KA7924TU is the most reliable choice from an availability standpoint.

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