MPS6601RLRA Equivalent & Substitute Parts

Part Overview

The MPS6601RLRA is an NPN bipolar junction transistor manufactured by onsemi, rated for 25 V collector-emitter breakdown voltage and 1 A maximum collector current in a TO-92 through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The MPS6601RLRA serves general-purpose switching and amplification applications requiring moderate voltage and current ratings with through-hole mounting.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	25	V
Current - Collector (Ic) (Max)	1	A
Power - Max	625	mW
Frequency - Transition	100	MHz
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Operating Temperature Range	-55 to 150	°C

Substitute Part Grouping Explanation

Substitution of the MPS6601RLRA is determined by the following critical parameters: NPN transistor type, through-hole TO-92 package compatibility, maximum collector current rating, collector-emitter breakdown voltage rating, and maximum power dissipation. A substitute part must maintain or exceed the electrical performance envelope of the original device while preserving the through-hole mounting form factor.

Substitute parts are grouped into two categories based on their electrical characteristics relative to the MPS6601RLRA:

Category A - Direct Functional Equivalents: Parts with collector current ratings at or above 1 A and collector-emitter breakdown voltages at or above 25 V, suitable for direct replacement in applications requiring the original specifications.

Category B - Reduced Current Applications: Parts with collector current ratings below 1 A or reduced voltage ratings, suitable only for applications where the full 1 A current capability is not required.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce Breakdown (Max) [V]	Power (Max) [mW]	Frequency [MHz]	Package	Product Status
MPS6601RLRA	onsemi	1	25	625	100	TO-92-3	Obsolete
KSD471AYTA	Fairchild Semiconductor	1	30	800	130	TO-92-3	Active
KSD471ACYTA	Fairchild Semiconductor	1	30	800	130	TO-92-3	Active
BC337-25-AP	Micro Commercial Co	0.8	45	625	210	TO-92-3	Obsolete
KSC1008YTA	onsemi	0.7	60	800	50	TO-92-3	Active
KSC945CYTA	onsemi	0.15	50	250	300	TO-92-3	Active
STSA1805-AP	STMicroelectronics	5	60	1100	150	TO-92-3	Last Time Buy

Engineering Selection Recommendations

Primary Substitutes (Category A - Direct Functional Equivalents):

KSD471AYTA and KSD471ACYTA are the preferred substitutes for the MPS6601RLRA. Both devices are manufactured by Fairchild Semiconductor and maintain active product status. These parts provide 1 A collector current capability with 30 V collector-emitter breakdown voltage, exceeding the original 25 V specification. Power dissipation is rated at 800 mW, providing additional margin over the 625 mW rating of the MPS6601RLRA. Transition frequency of 130 MHz exceeds the original 100 MHz specification. Both parts are RoHS3 compliant and available in high inventory quantities (43,260 pcs for KSD471AYTA and 5,946 pcs for KSD471ACYTA).

STSA1805-AP, manufactured by STMicroelectronics, provides superior electrical performance with 5 A collector current capability and 60 V breakdown voltage. This part is suitable for applications requiring higher current capacity than the original specification. Power dissipation of 1.1 W and transition frequency of 150 MHz provide enhanced performance margins. The device carries RoHS3 compliance and Last Time Buy status with 20,575 pcs in inventory.

Secondary Substitutes (Category B - Reduced Current Applications):

KSC1008YTA is suitable for applications where collector current requirements do not exceed 700 mA. This onsemi device provides 60 V breakdown voltage and 800 mW power dissipation with active product status and RoHS3 compliance. Transition frequency of 50 MHz is lower than the original specification.

KSC945CYTA is applicable only to low-current applications with collector current requirements not exceeding 150 mA. This device provides 50 V breakdown voltage and 300 MHz transition frequency. Power dissipation is limited to 250 mW.

BC337-25-AP, manufactured by Micro Commercial Co, is classified as obsolete and provides 800 mA collector current with 45 V breakdown voltage. This part is not recommended for new designs due to obsolete status, despite RoHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can KSD471AYTA directly replace MPS6601RLRA in all applications?

A: Yes, KSD471AYTA is a direct functional equivalent. It provides equal or superior performance across all critical parameters: 1 A collector current (matching the original), 30 V breakdown voltage (exceeding the 25 V specification), and 800 mW power dissipation (exceeding the 625 mW specification). Both devices use the TO-92-3 through-hole package with identical pinout and lead configuration.

Q: What is the difference between KSD471AYTA and KSD471ACYTA?

A: Both parts are electrically identical with the same electrical specifications: 1 A collector current, 30 V breakdown voltage, 130 MHz transition frequency, and 800 mW power dissipation. The difference lies in packaging: KSD471AYTA is supplied in bulk packaging, while KSD471ACYTA is supplied in bulk packaging. Both are manufactured by Fairchild Semiconductor and carry active product status.

Q: Is STSA1805-AP suitable for all MPS6601RLRA applications?

A: STSA1805-AP is electrically compatible with MPS6601RLRA applications but provides significantly higher performance specifications. With 5 A collector current capability and 60 V breakdown voltage, this device is suitable for applications requiring higher current handling or voltage margins. The TO-92-3 package maintains mechanical compatibility. However, the higher current rating may result in different thermal characteristics in the same package, requiring thermal analysis for high-power applications.

Q: Why is KSC945CYTA listed as a substitute if it only handles 150 mA?

A: KSC945CYTA is listed as a substitute for applications where the full 1 A capability of the MPS6601RLRA is not required. This device is suitable for low-current switching and amplification circuits. The 300 MHz transition frequency provides superior high-frequency performance compared to the original 100 MHz specification, making it advantageous for signal processing applications operating below 150 mA collector current.

Q: Are all substitute parts RoHS compliant?

A: KSD471AYTA, KSD471ACYTA, KSC1008YTA, KSC945CYTA, and STSA1805-AP are all RoHS3 compliant. BC337-25-AP is also RoHS3 compliant but carries obsolete product status. The original MPS6601RLRA is RoHS non-compliant.

Q: What is the significance of "Last Time Buy" status for STSA1805-AP?

A: Last Time Buy status indicates that STMicroelectronics has announced the end of production for STSA1805-AP. While the device remains available in inventory (20,575 pcs), no future production is planned. This status does not affect the electrical performance or compatibility of the part for current applications but indicates that long-term availability is limited.

Q: Can I use KSC1008YTA in a 1 A application?

A: KSC1008YTA is rated for a maximum collector current of 700 mA, which is below the 1 A requirement of the MPS6601RLRA. Using this device in a 1 A application would exceed its maximum ratings and result in device failure or degraded performance. This part is suitable only for applications requiring 700 mA or less.

Q: Are the TO-92-3 packages of all substitute parts mechanically identical?

A: All substitute parts use the TO-92-3 through-hole package with formed leads, providing mechanical compatibility with the MPS6601RLRA. The package designation TO-226-3 and TO-92-3 are equivalent specifications. Lead spacing, diameter, and length are standardized across all listed parts, allowing direct board-level substitution without PCB modification.

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