KA78L08AMTF Equivalent & Substitute Parts

Part Overview

The KA78L08AMTF is a linear voltage regulator IC manufactured by onsemi, delivering a fixed positive 8V output at 100mA in a surface-mount SOT-89-3 package. This device is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The KA78L08AMTF serves applications requiring regulated 8V power from input sources up to 30V, with integrated over-temperature and short-circuit protection.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	8V
Output Current	100mA
Input Voltage (Max)	30V
Quiescent Current	5.5 mA
PSRR @ 120Hz	70dB
Package Type	SOT-89-3 (TO-243AA)
Mounting Type	Surface Mount
Operating Temperature Range	-40°C to 125°C
Protection Features	Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution for the KA78L08AMTF is determined by strict equivalence across the following electrical and mechanical parameters:

Fixed output voltage of 8V
Output current capability of 100mA
Maximum input voltage of 30V or greater
Surface-mount SOT-89-3 package (TO-243AA)
Positive output configuration
Single regulator output

Substitute parts must maintain these core specifications to ensure direct functional replacement without circuit redesign. Package compatibility is mandatory for PCB layout preservation.

Parameter Comparison

Part Number	Manufacturer	Product Status	Output Voltage	Output Current	Input Voltage (Max)	Iq (mA)	PSRR @ 120Hz	Package	Mounting	Temp Range
KA78L08AMTF	onsemi	Obsolete	8V	100mA	30V	5.5	70dB	SOT-89-3	Surface Mount	-40°C to 125°C
MC78L08F-TP	Micro Commercial Co	Active	8V	100mA	30V	5.5	70dB	SOT-89	Surface Mount	0°C to 125°C
UA78L08ACPK	Texas Instruments	Last Time Buy	8V	100mA	23V	—	46dB	SOT-89-3	Surface Mount	0°C to 125°C
UA78L08ACPKG3	Texas Instruments	Last Time Buy	8V	100mA	23V	—	46dB	SOT-89-3	Surface Mount	0°C to 125°C
L78L08ABUTR	STMicroelectronics	Active	8V	100mA	30V	5.5	45dB	SOT-89-3	Surface Mount	-40°C to 125°C
L78L08ACUTR	STMicroelectronics	Active	8V	100mA	30V	5.5	45dB	SOT-89-3	Surface Mount	0°C to 125°C

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

MC78L08F-TP and L78L08ABUTR provide the closest electrical equivalence to the KA78L08AMTF. Both maintain the 30V maximum input voltage specification, 5.5mA quiescent current, and 70dB PSRR performance. MC78L08F-TP is actively manufactured by Micro Commercial Co. L78L08ABUTR is actively manufactured by STMicroelectronics and supports the full -40°C to 125°C operating range matching the original part.

Secondary Substitutes (Functional Equivalence with Constraints):

L78L08ACUTR (STMicroelectronics, Active) matches all electrical parameters of the KA78L08AMTF except operating temperature range, which is limited to 0°C to 125°C. This part is suitable for applications not requiring -40°C operation.

UA78L08ACPK and UA78L08ACPKG3 (Texas Instruments, Last Time Buy) are functionally equivalent but with reduced maximum input voltage (23V versus 30V) and lower PSRR (46dB versus 70dB). These parts are classified as Last Time Buy, indicating limited future availability.

Packaging Consideration:

MC78L08ACPRPG is a through-hole TO-92-3 package alternative from onsemi. This part is not a direct substitute due to different mounting technology (through-hole versus surface-mount) and different package footprint, requiring PCB redesign.

Frequently Asked Questions (FAQ)

Q: Can I use MC78L08F-TP as a direct replacement for KA78L08AMTF?

A: Yes. MC78L08F-TP is electrically and mechanically compatible. Both are SOT-89-3 surface-mount packages with identical 8V output, 100mA current rating, and 30V maximum input voltage. The primary difference is operating temperature range: MC78L08F-TP operates 0°C to 125°C versus KA78L08AMTF at -40°C to 125°C. For applications within 0°C to 125°C, this part is a direct substitute.

Q: Why do some substitutes have lower maximum input voltage (23V)?

A: UA78L08ACPK and UA78L08ACPKG3 from Texas Instruments specify 23V maximum input voltage compared to 30V for the KA78L08AMTF. These parts are functionally equivalent only in circuits where input voltage does not exceed 23V. Circuits designed for the full 30V input range require substitutes maintaining this specification.

Q: What is the difference between L78L08ABUTR and L78L08ACUTR?

A: Both are STMicroelectronics parts in SOT-89-3 packages with identical electrical specifications. The primary difference is operating temperature range: L78L08ABUTR supports -40°C to 125°C (matching KA78L08AMTF), while L78L08ACUTR is limited to 0°C to 125°C. Select L78L08ABUTR for applications requiring full temperature range operation.

Q: Are Texas Instruments UA78L08 parts suitable for new designs?

A: UA78L08ACPK and UA78L08ACPKG3 are classified as Last Time Buy, indicating discontinued production with limited inventory. These parts are not recommended for new designs. Use actively manufactured alternatives such as MC78L08F-TP or L78L08ABUTR instead.

Q: Can I use MC78L08ACPRPG (TO-92-3) in place of KA78L08AMTF (SOT-89-3)?

A: No. Although both are 8V 100mA linear regulators from onsemi, the package types are incompatible. MC78L08ACPRPG uses through-hole TO-92-3 mounting, while KA78L08AMTF uses surface-mount SOT-89-3. Direct substitution requires identical package footprint and mounting technology.

Q: What protection features should I verify when selecting a substitute?

A: The KA78L08AMTF includes over-temperature and short-circuit protection. Verify that selected substitutes include at minimum these protection features. L78L08ABUTR and L78L08ACUTR add over-current protection. UA78L08ACPK and UA78L08ACPKG3 include over-current, over-temperature, reverse-polarity, and short-circuit protection, providing enhanced circuit protection.

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