KA7908TU Equivalent & Substitute Parts

Part Overview

The KA7908TU is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed negative 8V output 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 production continuity. The KA7908TU serves applications requiring negative voltage regulation with thermal and short-circuit protection in through-hole mounting configurations.

Substiute Parts

KA7908TU

onsemiIn Stock: 53306KA7908TU Datasheet

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MC7808CTG

onsemiIn Stock: 1512MC7808CTG Datasheet

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MC79M08CTG

onsemiIn Stock: 1644MC79M08CTG Datasheet

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L7908CV

STMicroelectronicsIn Stock: 88990L7908CV Datasheet

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L7908CV-DG

STMicroelectronicsIn Stock: 25358L7908CV-DG Datasheet

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MC7908ACTG

onsemiIn Stock: 1170MC7908ACTG Datasheet

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UA7908CKCS

Texas InstrumentsIn Stock: 1426UA7908CKCS Datasheet

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UA7908CKCSE3

Texas InstrumentsIn Stock: 1390UA7908CKCSE3 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the KA7908TU is determined by the following critical parameters:

• Output Configuration: Negative voltage regulation
• Output Voltage: Fixed -8V
• Current - Output: Minimum 1A capability
• Package / Case: TO-220-3 form factor
• Voltage - Input (Max): Support for -35V or greater negative input
• Operating Temperature: 0°C ~ 125°C range
• Mounting Type: Through Hole

Substitute parts must maintain negative output polarity, fixed -8V regulation, and 1A or greater output current capacity. Package compatibility (TO-220-3) and thermal operating range are mandatory for direct board-level replacement. Input voltage rating and dropout voltage characteristics are secondary considerations based on application requirements.

Parameter Comparison

Engineering Selection Recommendations

For direct replacement of the KA7908TU, the following parts provide equivalent functionality:

Primary Equivalents (1A Output Current):

• MC7908ACTG (onsemi): Identical output current and voltage specifications with improved dropout voltage (1.3V vs 2V). Obsolete status.
• UA7908CKCS (Texas Instruments): Supports 1.5A output with lower dropout voltage (1.1V). Last Time Buy status provides extended availability window.
• UA7908CKCSE3 (Texas Instruments): Functionally identical to UA7908CKCS with Last Time Buy status.

Higher Current Alternatives (1.5A Output Current):

• L7908CV (STMicroelectronics): Provides 1.5A output capacity with 1.1V dropout voltage. Obsolete status.
• L7908CV-DG (STMicroelectronics): Variant of L7908CV with identical electrical specifications. Obsolete status.

Current-Limited Alternative (500mA Output Current):

• MC79M08CTG (onsemi): Reduced output current (500mA) suitable only for applications with lower current requirements. Not recommended for 1A designs.

Parts with Last Time Buy status (UA7908CKCS, UA7908CKCSE3) offer superior availability compared to obsolete alternatives. All substitute parts maintain TO-220-3 packaging and 0°C to 125°C operating temperature range. Input voltage rating differences (UA7908 series limited to -25V vs -35V for others) must be evaluated against application requirements.

Frequently Asked Questions (FAQ)

Q: Can MC7908ACTG directly replace KA7908TU? A: Yes. Both devices provide -8V fixed output at 1A in TO-220-3 packaging with identical operating temperature range. MC7908ACTG features improved dropout voltage (1.3V vs 2V), making it functionally superior for most applications.

Q: What is the difference between L7908CV and L7908CV-DG? A: Both parts are STMicroelectronics devices with identical electrical specifications: -8V output, 1.5A current, 1.1V dropout voltage, and TO-220-3 packaging. The suffix variation (-DG) indicates different manufacturing or distribution codes but does not affect electrical performance.

Q: Why is MC79M08CTG not recommended as a direct substitute? A: MC79M08CTG provides only 500mA output current compared to the KA7908TU's 1A rating. This part is suitable only for applications with lower current demands and will not support designs requiring full 1A output.

Q: What advantage do UA7908CKCS and UA7908CKCSE3 offer? A: Both Texas Instruments parts provide 1.5A output capacity with 1.1V dropout voltage, exceeding KA7908TU specifications. Critically, both maintain Last Time Buy status, providing extended procurement windows compared to fully obsolete alternatives. Both include over-current protection in addition to over-temperature and short-circuit protection.

Q: Are there input voltage limitations with Texas Instruments substitutes? A: UA7908CKCS and UA7908CKCSE3 support maximum -25V input, compared to -35V for the KA7908TU and most other alternatives. Applications requiring input voltages between -25V and -35V must use onsemi or STMicroelectronics alternatives.

Q: Do all substitute parts maintain the same pin configuration? A: Yes. All listed substitute parts use TO-220-3 packaging with identical pin assignments, enabling direct board-level replacement without layout modifications.

Q: Which substitute offers the best long-term availability? A: UA7908CKCS and UA7908CKCSE3 (Texas Instruments) maintain Last Time Buy status, providing superior availability compared to fully obsolete parts. These should be prioritized for new designs requiring extended production support.