KSC1674RTA Equivalent & Substitute Parts

Part Overview

The KSC1674RTA is an RF transistor NPN manufactured by onsemi, rated for 20V collector-emitter breakdown voltage with a transition frequency of 600MHz and maximum power dissipation of 250mW. This device is packaged in a through-hole TO-92-3 configuration and is classified as obsolete. Due to its obsolete status, equivalent and substitute parts are necessary for ongoing design support, production continuity, and system maintenance where the KSC1674RTA is no longer available from primary sources.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	20V	V
Frequency - Transition	600MHz	MHz
Noise Figure (Typ @ f)	3dB ~ 5dB @ 100MHz	dB
Power - Max	250mW	mW
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 1mA, 6V	—
Current - Collector (Ic) (Max)	20mA	mA
Operating Temperature (TJ)	150°C	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the KSC1674RTA is determined by the following critical parameters: transistor type (NPN), collector-emitter breakdown voltage rating, transition frequency capability, maximum power dissipation, and collector current rating. All substitute parts listed maintain NPN polarity and are evaluated for compatibility within the electrical operating envelope of the original device.

The substitute parts are grouped into two categories based on mounting technology:

Surface Mount Substitutes: BFP196E6327HTSA1, BFP540FESDH6327XTSA1, BFP843H6327XTSA1, BFS17NTA, and MMBTH10-TP represent active, currently manufactured alternatives with enhanced frequency performance and improved noise characteristics. These parts exceed the original specifications in transition frequency and power handling.

Substitution Criteria: All substitute parts maintain or exceed the 20V collector-emitter breakdown voltage requirement (with the exception of BFP540FESDH6327XTSA1 at 5V and BFP843H6327XTSA1 at 2.25V, which are suitable only for applications with lower voltage requirements). All substitutes support the 600MHz minimum frequency requirement and maintain the 250mW power dissipation threshold or higher. All substitute parts are classified as active products with current manufacturing status and full RoHS3 compliance.

Parameter Comparison

Parameter	KSC1674RTA	BFP196E6327HTSA1	BFP540FESDH6327XTSA1	BFP843H6327XTSA1	BFS17NTA	MMBTH10-TP
Manufacturer	onsemi	Infineon Technologies	Infineon Technologies	Infineon Technologies	Diodes Incorporated	Micro Commercial Co
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	20V	12V	5V	2.25V	11V	25V
Frequency - Transition	600MHz	7.5GHz	30GHz	—	3.2GHz	650MHz
Power - Max	250mW	700mW	250mW	125mW	330mW	225mW
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 1mA, 6V	70 @ 50mA, 8V	50 @ 20mA, 3.5V	150 @ 15mA, 1.8V	56 @ 5mA, 10V	60 @ 4mA, 10V
Current - Collector (Ic) (Max)	20mA	150mA	80mA	55mA	50mA	50mA
Operating Temperature (TJ)	150°C	150°C	150°C	150°C	-55°C ~ 150°C	-55°C ~ 150°C
Mounting Type	Through Hole	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-92-3	SOT-143-4	4-TSFP	SOT-343	SOT-23-3	SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

For Direct Voltage and Frequency Compatibility (20V+ Applications):

MMBTH10-TP is the closest electrical substitute for the KSC1674RTA, offering 25V collector-emitter breakdown voltage (exceeding the original 20V specification), 650MHz transition frequency (matching the original 600MHz requirement), and active product status with full RoHS3 compliance. This part is suitable for applications requiring through-hole-to-surface-mount conversion where voltage and frequency specifications are primary design constraints. The SOT-23-3 package provides a compact surface-mount alternative to the original TO-92-3 through-hole configuration.

For Enhanced Performance Applications (Lower Voltage Tolerance):

BFS17NTA provides 11V collector-emitter breakdown voltage with 3.2GHz transition frequency, representing a performance upgrade suitable for applications where voltage requirements are 11V or lower. This part maintains active product status and RoHS3 compliance.

For Ultra-High Frequency Applications (Specialized RF):

BFP540FESDH6327XTSA1 and BFP196E6327HTSA1 are suitable only for applications where the lower voltage ratings (5V and 12V respectively) are acceptable. These parts offer significantly enhanced transition frequencies (30GHz and 7.5GHz) and are appropriate for advanced RF applications requiring higher frequency performance than the original KSC1674RTA specification.

For Low-Voltage Applications:

BFP843H6327XTSA1 is limited to applications with 2.25V or lower collector-emitter voltage requirements and is not suitable as a general substitute for the KSC1674RTA.

All substitute parts maintain REACH Unaffected status and MSL Level 1 (Unlimited) moisture sensitivity classification, ensuring compatibility with standard manufacturing and storage environments.

Frequently Asked Questions (FAQ)

Q: Can MMBTH10-TP directly replace KSC1674RTA in existing through-hole PCB designs?

A: MMBTH10-TP is a surface-mount device in SOT-23-3 package, while KSC1674RTA is through-hole TO-92-3. Direct PCB replacement requires design modification. However, MMBTH10-TP provides electrical compatibility with 25V breakdown voltage and 650MHz frequency performance suitable for the original application requirements.

Q: What is the primary reason for substituting the KSC1674RTA?

A: The KSC1674RTA is classified as obsolete. Substitute parts are necessary to maintain design continuity, ensure production availability, and support long-term system maintenance where the original component is no longer manufactured or available from primary sources.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All five substitute parts (BFP196E6327HTSA1, BFP540FESDH6327XTSA1, BFP843H6327XTSA1, BFS17NTA, and MMBTH10-TP) are classified as ROHS3 Compliant and maintain REACH Unaffected status, ensuring regulatory compliance for modern manufacturing and distribution.

Q: Which substitute part has the closest voltage rating to the original KSC1674RTA?

A: MMBTH10-TP offers 25V collector-emitter breakdown voltage, which exceeds the original 20V specification and provides the closest match for applications requiring voltage headroom. BFS17NTA at 11V is suitable only for lower-voltage applications.

Q: Can BFP540FESDH6327XTSA1 or BFP843H6327XTSA1 be used as general substitutes?

A: BFP540FESDH6327XTSA1 (5V) and BFP843H6327XTSA1 (2.25V) have significantly lower voltage ratings than the original KSC1674RTA (20V) and are suitable only for specialized applications where the lower voltage requirements are acceptable. These parts are not recommended as general substitutes for standard 20V applications.

Q: What is the key difference between the original KSC1674RTA and MMBTH10-TP?

A: The primary difference is mounting technology: KSC1674RTA is through-hole TO-92-3, while MMBTH10-TP is surface-mount SOT-23-3. Electrically, MMBTH10-TP provides superior voltage rating (25V vs. 20V) and comparable frequency performance (650MHz vs. 600MHz). Both maintain identical operating temperature range (150°C maximum junction temperature) and moisture sensitivity classification (MSL Level 1).

Q: Are all substitute parts currently in active production?

A: Yes. All five substitute parts are classified as Active products, ensuring ongoing availability, manufacturing support, and compliance with current industry standards. The original KSC1674RTA is obsolete and no longer manufactured.

Q: What is the significance of MSL Level 1 (Unlimited) classification?

A: MSL Level 1 (Unlimited) indicates that the component has unlimited shelf life and does not require special moisture-controlled storage or handling procedures. All substitute parts maintain this classification, ensuring compatibility with standard manufacturing environments and storage conditions.

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