KA79M05 Equivalent & Substitute Parts

Part Overview

The KA79M05 is a linear voltage regulator IC manufactured by onsemi, delivering a fixed negative output of -5V at 500mA 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 KA79M05 serves applications requiring negative voltage regulation with moderate current capacity and thermal protection.

Key Parameters

Parameter	Value
Manufacturer Part Number	KA79M05
Manufacturer	onsemi
Category	Power Management (PMIC)
Output Configuration	Negative
Voltage - Output (Fixed)	-5V
Current - Output	500mA
Voltage - Input (Max)	-35V
Voltage Dropout (Max)	1.1V @ 500mA
Package / Case	TO-220-3
Operating Temperature	0°C ~ 125°C
Protection Features	Over Temperature, Short Circuit
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the KA79M05 is determined by the following critical parameters:

Output voltage: -5V fixed (non-negotiable)
Output configuration: Negative (required)
Package type: TO-220-3 (mechanical and thermal compatibility)
Maximum input voltage: -35V or greater
Output current capacity: 500mA minimum
Operating temperature range: 0°C to 125°C minimum
Protection features: Over temperature and short circuit protection

Substitute parts are grouped into two categories:

Direct Equivalents (500mA Output): Parts with identical electrical specifications and current rating, suitable for direct replacement without circuit modification.

Higher-Current Alternatives (1A or 1.5A Output): Parts with increased current capacity that maintain all other critical parameters, providing enhanced performance margin and design flexibility.

Parameter Comparison

Part Number	Manufacturer	Output Current	Voltage Dropout (Max)	Quiescent Current	PSRR	Operating Temp	Product Status	Package
KA79M05	onsemi	500mA	1.1V @ 500mA	6 mA	60dB (120Hz)	0°C ~ 125°C	Obsolete	TO-220-3
KA79M05TU	Fairchild Semiconductor	500mA	1.1V @ 500mA	6 mA	60dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
UA79M05CKCS	Texas Instruments	500mA	1.1V @ 350mA	—	60dB (120Hz)	0°C ~ 125°C	Last Time Buy	TO-220-3
MC7905BTG	onsemi	1A	1.3V @ 1A (Typ)	—	70dB (120Hz)	-40°C ~ 125°C	Active	TO-220-3
MC7905CTG	onsemi	1A	1.3V @ 1A (Typ)	—	70dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
L7905ACV	STMicroelectronics	1.5A	1.4V @ 1A (Typ)	3 mA	60dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
L7905ACV-DG	STMicroelectronics	1.5A	1.4V @ 1A (Typ)	3 mA	60dB (120Hz)	0°C ~ 125°C	Obsolete	TO-220-3
L7905CV	STMicroelectronics	1.5A	1.4V @ 1A (Typ)	3 mA	60dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
L7905CV-DG	STMicroelectronics	1.5A	1.4V @ 1A (Typ)	3 mA	60dB (120Hz)	0°C ~ 125°C	Active	TO-220-3

Engineering Selection Recommendations

For Direct Replacement (Pin-Compatible, No Circuit Modification):

KA79M05TU (Fairchild Semiconductor) is the primary direct equivalent. It maintains identical electrical specifications, current rating, and thermal characteristics as the KA79M05. This part is currently in active production status with 4230 units in stock, ensuring long-term availability.

UA79M05CKCS (Texas Instruments) provides an alternative direct replacement with identical 500mA output capacity. However, this part is designated Last Time Buy, indicating limited future availability. It includes enhanced protection features (over current, over temperature, short circuit) and carries RoHS3 compliance.

For Enhanced Performance (Higher Current Capacity):

MC7905CTG (onsemi) offers 1A output capacity while maintaining the same -5V output and TO-220-3 package. This part is in active production with 4000 units in stock and provides improved thermal performance margin. Operating temperature range extends to 0°C ~ 125°C, matching the original specification.

MC7905BTG (onsemi) provides 1A output with extended operating temperature range (-40°C ~ 125°C), suitable for applications requiring wider temperature operation. This part is actively produced with 1980 units available.

L7905CV (STMicroelectronics) delivers 1.5A output capacity with active production status and highest inventory availability (88,791 units). This part provides maximum design margin for current-limited applications and includes RoHS3 compliance.

L7905ACV (STMicroelectronics) is an alternative 1.5A source with active status and 11,200 units in stock, offering equivalent performance to L7905CV.

Compliance and Certification:

All recommended substitute parts maintain REACH Unaffected status and EAR99 classification, matching the original KA79M05. Parts designated as RoHS3 compliant (MC7905CTG, MC7905BTG, L7905 series) meet modern environmental standards.

Frequently Asked Questions (FAQ)

Q: Can I use MC7905CTG or L7905CV as a direct replacement for KA79M05?

A: Yes, both parts are electrically compatible. All three devices deliver -5V fixed negative output in TO-220-3 packages with identical pin configurations. MC7905CTG and L7905CV provide higher current capacity (1A and 1.5A respectively), which does not affect circuit operation when the original design requires only 500mA. No circuit modification is required.

Q: What is the difference between KA79M05TU and UA79M05CKCS?

A: Both are 500mA direct equivalents with identical output voltage and package. KA79M05TU is in active production, while UA79M05CKCS is Last Time Buy status. UA79M05CKCS includes over-current protection in addition to over-temperature and short-circuit protection. KA79M05TU has a maximum input voltage of -35V; UA79M05CKCS is rated to -25V maximum input.

Q: Why do the L7905 series parts have lower quiescent current (3mA vs 6mA)?

A: Lower quiescent current indicates more efficient internal design. This parameter is provided in the datasheet and does not affect substitution compatibility. The L7905 series maintains all other critical electrical specifications required for replacement.

Q: Are there any thermal considerations when substituting to higher-current parts?

A: All substitute parts use identical TO-220-3 packaging with equivalent thermal characteristics. Higher-current parts (1A, 1.5A) do not generate additional heat when operating at 500mA or below. If your circuit operates at the original 500mA specification, thermal performance remains unchanged.

Q: What is the difference between L7905ACV and L7905CV?

A: Both parts are electrically identical 1.5A regulators from STMicroelectronics. L7905ACV is in active production with 11,200 units in stock. L7905CV is also active with significantly higher inventory (88,791 units). Both maintain identical electrical specifications and TO-220-3 packaging. L7905CV offers superior availability for high-volume applications.

Q: Can I use parts marked as Obsolete (L7905ACV-DG, KA79M05)?

A: Obsolete parts should not be selected for new designs or long-term production. However, L7905ACV-DG remains available with 2,100 units in stock and maintains full electrical compatibility. For production continuity, prioritize parts with Active status: L7905CV, L7905ACV, MC7905CTG, or KA79M05TU.

Q: What does PSRR 60dB (120Hz) mean for my application?

A: PSRR (Power Supply Rejection Ratio) measures the regulator's ability to reject noise from the input supply. Higher PSRR values indicate better noise rejection. The KA79M05 and most direct equivalents provide 60dB at 120Hz. MC7905 series parts offer 70dB, providing superior noise rejection. This parameter does not affect substitution compatibility but may improve performance in noise-sensitive applications.

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