KA78L08AZBU Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The KA78L08AZBU is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 8V output at 100mA. This device features integrated over-temperature and short-circuit protection, operating across a wide temperature range of -40°C to 125°C. The part is currently classified as obsolete, making identification of functionally equivalent substitutes essential for ongoing design support and production continuity. Equivalent alternatives maintain the same electrical performance characteristics and TO-92-3 package configuration, enabling direct replacement in existing applications.

Substiute Parts

KA78L08AZBU

onsemiIn Stock: 849KA78L08AZBU Datasheet

Current PartRFQ

L78L08ACZ

STMicroelectronicsIn Stock: 9140L78L08ACZ Datasheet

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UA78L08ACLP

Texas InstrumentsIn Stock: 2986UA78L08ACLP Datasheet

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UA78L08ACLPE3

Texas InstrumentsIn Stock: 3717UA78L08ACLPE3 Datasheet

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UA78L08ACLPR

Texas InstrumentsIn Stock: 2269UA78L08ACLPR Datasheet

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UA78L08ACLPRE3

Texas InstrumentsIn Stock: 4726UA78L08ACLPRE3 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the KA78L08AZBU is determined by the following critical parameters:

• Fixed 8V positive output voltage
• 100mA output current capability
• TO-92-3 package configuration
• Through-hole mounting compatibility
• Positive output configuration with fixed regulation type

The identified substitute parts maintain these core electrical and mechanical specifications. Variations in maximum input voltage (30V vs. 23V), quiescent current specifications, PSRR values, and operating temperature ranges represent secondary differences that do not prevent functional substitution in applications designed within the more restrictive parameter envelope.

Parameter Comparison

Engineering Selection Recommendations

For applications currently using the KA78L08AZBU, the L78L08ACZ from STMicroelectronics represents the primary substitute option due to its active product status and full compatibility with the original part's electrical specifications, including the 30V maximum input voltage rating. This part is currently in stock with substantial inventory availability.

For designs with extended low-temperature operation requirements below 0°C, the KA78L08AZBU's -40°C minimum operating temperature cannot be matched by the identified substitutes, which are rated to 0°C minimum. In such applications, alternative regulator architectures may require evaluation.

The Texas Instruments UA78L08 variants (UA78L08ACLP, UA78L08ACLPE3, UA78L08ACLPR, UA78L08ACLPRE3) provide functional equivalence with the trade-off of reduced maximum input voltage (23V vs. 30V). These parts are suitable for applications where input voltage does not exceed 23V. The UA78L08ACLPR and UA78L08ACLPRE3 variants are designated as Last Time Buy, indicating limited future availability.

All substitute parts maintain RoHS3 compliance and REACH unaffected status, consistent with the original part's regulatory classification.

Frequently Asked Questions (FAQ)

Q: Can the L78L08ACZ directly replace the KA78L08AZBU in all applications?

A: The L78L08ACZ is electrically and mechanically compatible with the KA78L08AZBU for applications operating within 0°C to 125°C. Applications requiring operation below 0°C require the original KA78L08AZBU or alternative parts with extended temperature ratings.

Q: What is the significance of the 30V vs. 23V maximum input voltage difference?

A: The KA78L08AZBU and L78L08ACZ support 30V maximum input, while UA78L08 variants support 23V maximum input. For circuits designed with input voltages between 23V and 30V, only the KA78L08AZBU or L78L08ACZ are suitable. Circuits operating below 23V input can use any substitute.

Q: Are the Texas Instruments UA78L08 variants interchangeable with each other?

A: The UA78L08ACLP, UA78L08ACLPE3, UA78L08ACLPR, and UA78L08ACLPRE3 variants are electrically identical. Differences exist only in packaging format (Bulk vs. Cut Tape) and lead configuration (standard vs. formed leads). Selection depends on procurement and assembly requirements.

Q: Why do substitute parts show different protection features than the original?

A: The L78L08ACZ and UA78L08 variants include over-current and reverse-polarity protection in addition to the over-temperature and short-circuit protection of the KA78L08AZBU. These additional protections enhance circuit robustness and do not prevent substitution.

Q: What is the impact of PSRR differences between parts?

A: The KA78L08AZBU specifies 70dB PSRR at 120Hz, while substitutes range from 45dB to 46dB. Lower PSRR indicates reduced rejection of input ripple. For noise-sensitive applications, the original part's superior PSRR may be preferred, but substitutes remain functionally adequate for standard linear regulation applications.

Q: Is the L78L08ACZ recommended for new designs?

A: The L78L08ACZ is the only identified substitute with active product status. For new designs requiring an 8V, 100mA linear regulator in TO-92-3 package, the L78L08ACZ is the appropriate selection.