KSC1674COTA Equivalent & Substitute Parts

Part Overview

The KSC1674COTA is an RF transistor NPN manufactured by onsemi, rated for 20V collector-emitter breakdown voltage with 600MHz transition frequency and 250mW maximum power dissipation in a through-hole TO-92-3 package. This component is classified as obsolete, making substitute parts necessary for new designs and ongoing production requirements. The part operates at a maximum junction temperature of 150°C with a DC current gain (hFE) minimum of 70 at 1mA collector current and 6V collector-emitter voltage.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	20	V
Frequency - Transition	600	MHz
Power - Max	250	mW
Current - Collector (Ic) (Max)	20	mA
DC Current Gain (hFE) (Min) @ Ic, Vce	70 @ 1mA, 6V	—
Noise Figure (dB Typ @ f)	3dB ~ 5dB @ 100MHz	dB
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the KSC1674COTA is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor type must be NPN
Voltage rating (Vce breakdown) must equal or exceed 20V
Frequency capability must support or exceed 600MHz transition frequency
Maximum collector current must equal or exceed 20mA
Power dissipation capability must equal or exceed 250mW
DC current gain (hFE) must meet or exceed 70 at specified operating conditions
Operating temperature range must support 150°C junction temperature

Secondary Considerations:

Mounting type (through-hole preferred for direct replacement; surface-mount requires board redesign)
Package compatibility (TO-92-3 is standard for through-hole RF transistors)
Noise figure performance at RF frequencies
Compliance certifications (RoHS, REACH status)

The substitute parts identified fall into two categories based on mounting technology: through-hole compatible replacements and surface-mount alternatives requiring circuit board modification.

Parameter Comparison

Parameter	KSC1674COTA (Main)	2SC4215-Y(TE85L,F)	BFP842ESDH6327XTSA1	BFS 17P E6433	MAX2602ESA+
Manufacturer	onsemi	Toshiba Semiconductor and Storage	Infineon Technologies	Infineon Technologies	Analog Devices Inc./Maxim Integrated
Transistor Type	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	20V	30V	3.7V	15V	15V
Frequency - Transition	600MHz	550MHz	60GHz	1.4GHz	1GHz
Noise Figure (dB Typ @ f)	3dB ~ 5dB @ 100MHz	2dB ~ 5dB @ 100MHz	0.65dB @ 3.5GHz	3.5dB ~ 5dB @ 800MHz	3.3dB @ 836MHz
Power - Max	250mW	100mW	120mW	280mW	6.4W
DC Current Gain (hFE) (Min) @ Ic, Vce	70 @ 1mA, 6V	100 @ 1mA, 6V	150 @ 15mA, 2.5V	40 @ 2mA, 1V	100 @ 250mA, 3V
Current - Collector (Ic) (Max)	20mA	20mA	40mA	25mA	1.2A
Operating Temperature (TJ)	150°C	125°C	150°C	150°C	150°C
Mounting Type	Through Hole	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-92-3	SC-70, SOT-323	SC-82A, SOT-343	SC-59, SOT-23-3	8-SOIC (0.154", 3.90mm Width) Exposed Pad
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Through-Hole Replacement: No direct through-hole equivalent exists among the identified substitute parts. All active substitute parts utilize surface-mount packaging (SC-70, SOT-343, SOT-23-3, or 8-SOIC), requiring circuit board redesign for implementation.

Surface-Mount Alternatives by Application:

2SC4215-Y(TE85L,F) (Toshiba):

Voltage rating of 30V exceeds the 20V requirement
Frequency capability of 550MHz is within acceptable range for 600MHz applications
Maximum power of 100mW is below the 250mW specification; suitable only for lower-power applications
DC current gain of 100 exceeds the 70 minimum requirement
Operating temperature limited to 125°C (below 150°C specification)
Active product status with ROHS3 compliance
SC-70 package provides compact surface-mount footprint

BFP842ESDH6327XTSA1 (Infineon):

Voltage rating of 3.7V is insufficient for 20V applications; not suitable for direct substitution
Frequency capability of 60GHz far exceeds 600MHz requirement
Power rating of 120mW is below 250mW specification
DC current gain of 150 exceeds requirement
Operating temperature of 150°C matches specification
Active product status with ROHS3 compliance
SOT-343 package provides ultra-compact surface-mount option

BFS 17P E6433 (Infineon):

Voltage rating of 15V is below the 20V requirement; marginal for 20V applications
Frequency capability of 1.4GHz exceeds 600MHz requirement
Maximum power of 280mW exceeds 250mW specification
DC current gain of 40 is below the 70 minimum requirement
Operating temperature of 150°C matches specification
Active product status with ROHS3 compliance
SOT-23-3 package provides standard surface-mount footprint

MAX2602ESA+ (Analog Devices Inc./Maxim Integrated):

Voltage rating of 15V is below the 20V requirement; marginal for 20V applications
Frequency capability of 1GHz exceeds 600MHz requirement
Maximum power of 6.4W significantly exceeds 250mW specification
DC current gain of 100 exceeds requirement
Operating temperature of 150°C matches specification
Active product status with ROHS3 compliance
8-SOIC-EP package provides higher current handling capability

Compliance Status: All substitute parts carry ROHS3 compliance and REACH unaffected status, meeting modern regulatory requirements. The KSC1674COTA is not subject to RoHS restrictions due to its obsolete status.

Frequently Asked Questions (FAQ)

Q: Can the 2SC4215-Y(TE85L,F) directly replace the KSC1674COTA?

A: No. While the 2SC4215-Y provides superior voltage rating (30V) and current gain (100), its maximum power dissipation of 100mW is insufficient for applications requiring the full 250mW capability of the KSC1674COTA. Additionally, the operating temperature is limited to 125°C, below the 150°C specification. Surface-mount packaging requires board redesign.

Q: Is the BFP842ESDH6327XTSA1 suitable for RF applications at 600MHz?

A: The BFP842ESDH6327XTSA1 is designed for ultra-high-frequency applications (60GHz) and exceeds the 600MHz requirement. However, its voltage rating of 3.7V is incompatible with the 20V specification of the KSC1674COTA, making it unsuitable for direct substitution in circuits requiring higher voltage operation.

Q: What are the key limitations of the BFS 17P E6433?

A: The BFS 17P E6433 has two significant limitations: voltage rating of 15V falls below the 20V requirement, and DC current gain of 40 is below the 70 minimum specification. These parameters may cause circuit performance degradation in applications dependent on the original specifications.

Q: Why does the MAX2602ESA+ have such high power rating compared to the KSC1674COTA?

A: The MAX2602ESA+ is designed for higher-current RF power amplifier applications, with maximum collector current of 1.2A and power dissipation of 6.4W. The KSC1674COTA is limited to 20mA and 250mW. The MAX2602ESA+ is suitable only for applications where higher power handling is required or acceptable.

Q: Can I use a surface-mount substitute in a through-hole circuit?

A: Surface-mount substitutes require circuit board redesign and cannot be directly installed in through-hole footprints. Adapter boards or complete PCB redesign is necessary. No through-hole equivalent is available among the identified active substitute parts.

Q: What is the impact of the 125°C operating temperature limit on the 2SC4215-Y?

A: The 2SC4215-Y operating temperature of 125°C is 25°C below the KSC1674COTA specification of 150°C. In applications operating near thermal limits, this reduction may require additional thermal management or circuit derating to maintain reliability.

Q: Are all substitute parts RoHS compliant?

A: Yes. All identified substitute parts carry ROHS3 compliance certification. The KSC1674COTA, being obsolete, is not subject to RoHS requirements but is REACH unaffected.

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