KSC1008COTA Equivalent & Substitute Parts

Part Overview

The KSC1008COTA is an NPN bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 700 mA maximum collector current. This device is packaged in a TO-92-3 through-hole configuration and is rated for 800 mW maximum power dissipation with a 50 MHz transition frequency. The KSC1008COTA is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	60	V
Current - Collector (Ic) (Max)	700	mA
Power - Max	800	mW
Frequency - Transition	50	MHz
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Operating Temperature (Max)	150	°C

Substitute Part Grouping Explanation

Substitution of the KSC1008COTA is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN
Collector-emitter breakdown voltage must be greater than or equal to 60 V
Maximum collector current must be greater than or equal to 700 mA
Maximum power dissipation must be greater than or equal to 800 mW
Transition frequency must support the intended application frequency range

Mechanical Compatibility Criteria:

Mounting type must be through-hole
Package must be TO-92-3 or equivalent TO-226-3 configuration

Substitute parts are grouped into two categories:

Category 1 - Direct Electrical Equivalents: Parts that meet or exceed all electrical specifications of the KSC1008COTA while maintaining identical or superior performance characteristics.

Category 2 - Functional Alternatives: Parts that provide NPN transistor functionality in the same package with electrical ratings that support the same application envelope, though with variations in specific parameters such as DC current gain or saturation voltage.

Parameter Comparison

Parameter	KSC1008COTA (Main)	KSC1008YBU	BC337-25-AP	BC337-AP
Manufacturer	onsemi	Fairchild Semiconductor	Micro Commercial Co	Micro Commercial Co
Product Status	Obsolete	Active	Obsolete	Active
Transistor Type	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	60 V	60 V	45 V	45 V
Current - Collector (Ic) (Max)	700 mA	700 mA	800 mA	800 mA
Power - Max	800 mW	800 mW	625 mW	625 mW
Frequency - Transition	50 MHz	50 MHz	210 MHz	210 MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	70 @ 50mA, 2V	120 @ 50mA, 2V	160 @ 100mA, 1V	60 @ 300mA, 1V
Vce Saturation (Max) @ Ib, Ic	400mV @ 50mA, 500mA	400mV @ 50mA, 500mA	700mV @ 50mA, 500mA	700mV @ 50mA, 500mA
Current - Collector Cutoff (Max)	100 nA	100 nA	200 nA	200 nA
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3
Operating Temperature (Max)	150°C	150°C	150°C	150°C

Engineering Selection Recommendations

KSC1008YBU (Fairchild Semiconductor)

The KSC1008YBU is the primary substitute for the KSC1008COTA. This part maintains identical electrical specifications across all critical parameters: 60 V collector-emitter breakdown voltage, 700 mA maximum collector current, 800 mW power dissipation, and 50 MHz transition frequency. The KSC1008YBU is currently in active production status, ensuring long-term availability and supply chain continuity. The part is packaged identically in TO-92-3 configuration with through-hole mounting. The DC current gain (hFE) of 120 @ 50mA, 2V exceeds the KSC1008COTA minimum specification of 70, providing improved performance margin. This part is recommended as the direct replacement for new designs and production continuity.

BC337-25-AP (Micro Commercial Co)

The BC337-25-AP is a functional alternative with reduced electrical ratings. The collector-emitter breakdown voltage is 45 V, which is 15 V lower than the KSC1008COTA specification. The maximum power dissipation is 625 mW, which is 175 mW lower than the main part. These reductions in voltage and power ratings restrict the BC337-25-AP to applications where the KSC1008COTA operates below 45 V and dissipates less than 625 mW. The BC337-25-AP offers higher transition frequency (210 MHz) and higher DC current gain (160 @ 100mA, 1V), which may provide performance benefits in high-frequency applications. This part is classified as obsolete. Selection of this part requires verification that application voltage and power requirements do not exceed the reduced ratings.

BC337-AP (Micro Commercial Co)

The BC337-AP is functionally similar to the BC337-25-AP with identical electrical ratings: 45 V collector-emitter breakdown voltage and 625 mW maximum power dissipation. The BC337-AP is currently in active production status, providing supply availability. The DC current gain specification differs at 60 @ 300mA, 1V, which is lower than both the KSC1008COTA and BC337-25-AP at comparable test conditions. Like the BC337-25-AP, the BC337-AP is restricted to applications operating below 45 V and 625 mW. The higher transition frequency (210 MHz) supports high-frequency switching applications. This part is recommended only for applications where voltage and power constraints are compatible with the reduced ratings and where active production status is required.

Frequently Asked Questions (FAQ)

Q: Can the KSC1008YBU directly replace the KSC1008COTA without circuit modification?

A: Yes. The KSC1008YBU maintains identical electrical specifications for voltage, current, power, and frequency ratings. The TO-92-3 package and through-hole mounting are identical. No circuit modification is required for direct substitution.

Q: What are the limitations of using BC337-25-AP or BC337-AP as substitutes?

A: Both BC337 variants have reduced collector-emitter breakdown voltage (45 V versus 60 V) and reduced maximum power dissipation (625 mW versus 800 mW). These parts are suitable only for applications where the circuit operates below 45 V and the transistor dissipates less than 625 mW. Applications requiring the full 60 V rating or higher power dissipation cannot use these parts.

Q: Are all substitute parts available in the same TO-92-3 package?

A: Yes. All substitute parts listed are packaged in TO-92-3 through-hole configuration, which is mechanically and electrically compatible with the KSC1008COTA. No PCB layout or mechanical modifications are required.

Q: What is the difference in DC current gain between the main part and substitutes?

A: The KSC1008COTA specifies a minimum DC current gain (hFE) of 70 @ 50mA, 2V. The KSC1008YBU specifies 120 @ 50mA, 2V, providing higher gain. The BC337 variants specify higher gain values at different test conditions (160 @ 100mA, 1V for BC337-25-AP and 60 @ 300mA, 1V for BC337-AP). Higher DC current gain reduces base drive requirements and improves switching efficiency.

Q: Why is the KSC1008COTA classified as obsolete?

A: The KSC1008COTA is marked as obsolete by the manufacturer. The KSC1008YBU from Fairchild Semiconductor is the recommended active production alternative with identical specifications.

Q: Can BC337 parts be used in high-frequency applications?

A: Yes. The BC337 variants have a transition frequency of 210 MHz, which is significantly higher than the KSC1008COTA at 50 MHz. This makes BC337 parts suitable for high-frequency switching applications, provided the voltage and power constraints are met.

Q: What compliance certifications apply to these parts?

A: All parts listed are classified as REACH Unaffected and carry EAR99 export classification. The BC337 variants are RoHS3 Compliant. All parts have Moisture Sensitivity Level (MSL) of 1 (Unlimited), indicating no moisture sensitivity restrictions.

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