KSC1008OBU Equivalent & Substitute Parts

Part Overview

The KSC1008OBU is an NPN bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 700 mA maximum collector current in a TO-92-3 through-hole package. This device is classified as obsolete, necessitating identification of active substitute components that maintain electrical and mechanical compatibility for existing designs or production requirements.

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
Vce Saturation (Max) @ Ib, Ic	400 mV @ 50 mA, 500 mA	V
DC Current Gain (hFE) (Min) @ Ic, Vce	70 @ 50 mA, 2 V	—
Operating Temperature (Max)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—

Substitute Part Grouping Explanation

Substitute parts for the KSC1008OBU are selected based on the following critical parameters that determine functional equivalence:

Primary Substitution Criteria:

Transistor Type: NPN (standard or Darlington configuration)
Voltage - Collector Emitter Breakdown (Max): ≥ 60 V
Current - Collector (Ic) (Max): ≥ 700 mA
Power - Max: ≥ 800 mW
Mounting Type: Through Hole
Package Compatibility: TO-92-3 or TO-92 compatible form factors

Substitute Categories:

Group 1: Direct Electrical Equivalents (Standard NPN) Parts that match or exceed all primary electrical specifications with standard NPN topology:

2N5822 PBFREE (Central Semiconductor Corp)
ZTX451STZ (Diodes Incorporated)
ZTX451 (Diodes Incorporated)

Group 2: Darlington Configuration Substitutes Parts that exceed electrical specifications through Darlington topology, providing higher current gain and saturation characteristics:

BCX38C (Diodes Incorporated)
BCX38CSTZ (Diodes Incorporated)

Group 3: Partial Specification Match Parts with matching voltage and package but incomplete parameter documentation:

BCX38A PBFREE (Central Semiconductor Corp)

Parameter Comparison

Parameter	KSC1008OBU	2N5822 PBFREE	BCX38A PBFREE	BCX38C	BCX38CSTZ	ZTX451	ZTX451STZ
Manufacturer	onsemi	Central Semiconductor Corp	Central Semiconductor Corp	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
Transistor Type	NPN	NPN	NPN	NPN - Darlington	NPN - Darlington	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	60 V	70 V	60 V	60 V	60 V	60 V	60 V
Current - Collector (Ic) (Max)	700 mA	750 mA	—	800 mA	800 mA	1 A	1 A
Power - Max	800 mW	1.5 W	—	1 W	1 W	1 W	1 W
Frequency - Transition	50 MHz	120 MHz	—	—	—	150 MHz	150 MHz
Vce Saturation (Max) @ Ib, Ic	400 mV @ 50 mA, 500 mA	1.2 V @ 50 mA, 500 mA	—	1.25 V @ 8 mA, 800 mA	1.25 V @ 8 mA, 800 mA	350 mV @ 15 mA, 150 mA	350 mV @ 15 mA, 150 mA
DC Current Gain (hFE) (Min) @ Ic, Vce	70 @ 50 mA, 2 V	100 @ 2 mA, 2 V	1000 @ 500 mA, 5 V	10000 @ 500 mA, 5 V	10000 @ 500 mA, 5 V	50 @ 150 mA, 10 V	50 @ 150 mA, 10 V
Operating Temperature (Max)	150 °C	150 °C	—	200 °C	200 °C	200 °C	200 °C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	E-Line-3	E-Line-3	E-Line-3
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

For Direct Replacement with Active Product Status:

The 2N5822 PBFREE (Central Semiconductor Corp) provides the closest functional match to the KSC1008OBU. This part maintains NPN topology, exceeds the 60 V breakdown voltage specification at 70 V, and provides 750 mA collector current capacity. The device is active in production, ROHS3 compliant, and REACH unaffected. The higher transition frequency (120 MHz versus 50 MHz) and increased power dissipation capability (1.5 W versus 800 mW) offer design margin without introducing incompatibility.

For Enhanced Performance Requirements:

The ZTX451STZ (Diodes Incorporated) offers superior electrical performance with 1 A collector current capacity, 150 MHz transition frequency, and 1 W power rating. This part is supplied in Tape & Box packaging with formed leads and E-Line package compatibility. The device is active in production with extended operating temperature range (-55°C to 200°C) and full compliance certifications.

For High Current Gain Applications:

The BCX38C and BCX38CSTZ (Diodes Incorporated) employ Darlington configuration, providing 10,000 minimum current gain at 500 mA collector current. These parts maintain 60 V breakdown voltage and 800 mA collector current capacity with 1 W power dissipation. The Darlington topology introduces higher saturation voltage (1.25 V) compared to the standard NPN KSC1008OBU (400 mV), requiring circuit evaluation for switching applications.

Compliance and Availability:

All substitute parts listed are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements. Active product status ensures continued availability and manufacturing support.

Frequently Asked Questions (FAQ)

Q: Can the 2N5822 PBFREE directly replace the KSC1008OBU in existing designs?

A: The 2N5822 PBFREE meets or exceeds all primary electrical specifications of the KSC1008OBU. Both devices are NPN transistors in TO-92-3 compatible packages with matching 60 V+ breakdown voltage and ≥700 mA collector current ratings. The 2N5822 PBFREE is active in production, addressing the obsolescence of the KSC1008OBU. Circuit validation is required to confirm performance in specific applications.

Q: What is the difference between standard NPN and Darlington substitute options?

A: Standard NPN substitutes (2N5822 PBFREE, ZTX451, ZTX451STZ) maintain the original transistor topology with lower saturation voltage and moderate current gain. Darlington substitutes (BCX38C, BCX38CSTZ) employ a compound transistor structure providing significantly higher current gain (10,000 versus 70-100) but with higher saturation voltage (1.25 V versus 400 mV). Darlington devices are suitable for low-signal-level switching and high-impedance source applications; standard NPN devices are preferred for linear amplification and low-saturation-voltage switching.

Q: Are E-Line packages compatible with TO-92-3 footprints?

A: E-Line packages are through-hole compatible with TO-92 footprints. The ZTX451, ZTX451STZ, BCX38C, and BCX38CSTZ are specified as E-Line (TO-92 compatible), indicating mechanical and electrical pin compatibility with standard TO-92-3 PCB layouts. Physical lead forming may differ; verification of lead spacing and bend radius is required for automated assembly processes.

Q: What is the significance of the higher transition frequency in ZTX451 devices?

A: The ZTX451 series provides 150 MHz transition frequency compared to the KSC1008OBU's 50 MHz. Higher transition frequency indicates improved high-frequency performance and faster switching response. This specification is relevant for RF amplification, high-speed switching circuits, and applications operating near or above 50 MHz. For DC or low-frequency switching applications, transition frequency difference is not a limiting factor.

Q: Why does the BCX38A PBFREE show incomplete parameter documentation?

A: The BCX38A PBFREE datasheet provided contains limited electrical specifications, with several parameters marked as unavailable (—). This part is included in the substitute list based on matching voltage rating (60 V) and package compatibility (TO-92-3). Complete datasheet review from the manufacturer is required before selection for critical applications.

Q: How do saturation voltage differences affect circuit design?

A: The KSC1008OBU specifies 400 mV saturation voltage at 50 mA base current and 500 mA collector current. The 2N5822 PBFREE specifies 1.2 V under the same conditions, while Darlington devices (BCX38C, BCX38CSTZ) specify 1.25 V at different bias points. Higher saturation voltage increases power dissipation in saturated switching applications and reduces output voltage swing in logic circuits. Circuit analysis is required to confirm acceptable performance margins.

Q: What packaging options are available for production quantities?

A: Substitute parts are available in multiple packaging formats: Bulk (2N5822 PBFREE, BCX38A PBFREE, BCX38C, ZTX451), Cut Tape (BCX38CSTZ), and Tape & Box (ZTX451STZ). Packaging selection depends on assembly process requirements and order quantities. All parts maintain identical electrical specifications across packaging variants.

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