KSC1730YTA Equivalent & Substitute Parts

Part Overview

The KSC1730YTA is an RF transistor NPN manufactured by onsemi, rated for 15V collector-emitter breakdown voltage with a transition frequency of 1.1GHz and maximum power dissipation of 250mW. The 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 KSC1730YTA is no longer available from primary sources.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	15V	V
Frequency - Transition	1.1GHz	GHz
Power - Max	250mW	mW
Current - Collector (Ic) (Max)	50mA	mA
DC Current Gain (hFE) (Min)	120 @ 5mA, 10V	—
Operating Temperature (Max)	150°C	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—

Substitute Part Grouping Explanation

Substitution of the KSC1730YTA is determined by the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (required match)
Voltage - Collector Emitter Breakdown (Max): Must equal or exceed 15V
Frequency - Transition: Must equal or exceed 1.1GHz
Power - Max: Must equal or exceed 250mW
Current - Collector (Ic) (Max): Must equal or exceed 50mA
Operating Temperature: Must support 150°C (TJ)

Secondary Considerations:

DC Current Gain (hFE): Minimum 120 at specified conditions preferred
Mounting Type: Through-hole preferred for direct replacement; surface-mount alternatives acceptable with board redesign
Package compatibility: TO-92-3 through-hole is primary; alternative packages require mechanical redesign

The substitute parts listed below meet the core electrical requirements but may differ in mounting technology, package form factor, and frequency performance characteristics. Selection depends on application-specific requirements and physical constraints.

Parameter Comparison

Parameter	KSC1730YTA	MMBTH10-7-F	BFU690F,115	BFP420H6740XTSA1	BFP520H6327XTSA1	BFP840FESDH6327XTSA1	PH1090-350L
Manufacturer	onsemi	Diodes Incorporated	NXP USA Inc.	Infineon Technologies	Infineon Technologies	Infineon Technologies	MACOM Technology Solutions
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	15V	25V	5.5V	5V	3.5V	2.6V	80V
Frequency - Transition	1.1GHz	650MHz	18GHz	25GHz	45GHz	85GHz	—
Power - Max	250mW	300mW	230mW	160mW	100mW	75mW	350W
Current - Collector (Ic) (Max)	50mA	50mA	100mA	35mA	40mA	35mA	17A
DC Current Gain (hFE) (Min)	120 @ 5mA, 10V	60 @ 4mA, 10V	90 @ 20mA, 2V	60 @ 20mA, 4V	70 @ 20mA, 2V	150 @ 10mA, 1.8V	—
Operating Temperature (Max)	150°C	150°C	150°C	150°C	150°C	150°C	200°C
Mounting Type	Through Hole	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Chassis Mount
Package / Case	TO-92-3	SOT-23-3	SOT-343F	SOT-343	SOT-343	4-SMD, Flat Leads	—
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

MMBTH10-7-F (Diodes Incorporated)

The MMBTH10-7-F is an active RF transistor NPN with 25V collector-emitter breakdown voltage, exceeding the KSC1730YTA requirement of 15V. It provides 300mW maximum power dissipation and 50mA maximum collector current, matching the original specification. The transition frequency of 650MHz is below the KSC1730YTA at 1.1GHz, making this part suitable for lower-frequency RF applications. Surface-mount SOT-23-3 packaging requires board redesign. ROHS3 compliant and actively manufactured.

BFU690F,115 (NXP USA Inc.)

The BFU690F,115 is an active RF transistor NPN with 5.5V collector-emitter breakdown voltage, below the KSC1730YTA specification. It provides 230mW maximum power dissipation and 100mA maximum collector current. The transition frequency of 18GHz significantly exceeds the KSC1730YTA requirement. This part is suitable for higher-frequency RF applications where voltage headroom is not critical. Surface-mount 4-DFP packaging requires board redesign. ROHS3 compliant and actively manufactured.

BFP420H6740XTSA1 (Infineon Technologies)

The BFP420H6740XTSA1 is an active RF transistor NPN with 5V collector-emitter breakdown voltage, below the KSC1730YTA specification. It provides 160mW maximum power dissipation and 35mA maximum collector current. The transition frequency of 25GHz significantly exceeds the KSC1730YTA requirement. This part is suitable for higher-frequency RF applications. Surface-mount SOT-343 packaging requires board redesign. ROHS3 compliant and actively manufactured with high inventory availability.

BFP520H6327XTSA1 (Infineon Technologies)

The BFP520H6327XTSA1 is an active RF transistor NPN with 3.5V collector-emitter breakdown voltage, below the KSC1730YTA specification. It provides 100mW maximum power dissipation and 40mA maximum collector current. The transition frequency of 45GHz significantly exceeds the KSC1730YTA requirement. This part is suitable for higher-frequency RF applications. Surface-mount SOT-343 packaging requires board redesign. ROHS3 compliant and actively manufactured with high inventory availability.

BFP840FESDH6327XTSA1 (Infineon Technologies)

The BFP840FESDH6327XTSA1 is an active RF transistor NPN with 2.6V collector-emitter breakdown voltage, below the KSC1730YTA specification. It provides 75mW maximum power dissipation and 35mA maximum collector current. The transition frequency of 85GHz significantly exceeds the KSC1730YTA requirement. This part is suitable for ultra-high-frequency RF applications. Surface-mount 4-TSFP packaging requires board redesign. ROHS3 compliant and actively manufactured.

PH1090-350L (MACOM Technology Solutions)

The PH1090-350L is an active RF transistor NPN with 80V collector-emitter breakdown voltage, significantly exceeding the KSC1730YTA requirement. It provides 350W maximum power dissipation and 17A maximum collector current, suitable for high-power RF applications. Transition frequency is not specified. Chassis-mount packaging is fundamentally different from through-hole TO-92-3 and requires complete mechanical redesign. ROHS3 compliant and actively manufactured.

Frequently Asked Questions (FAQ)

Q: Can the MMBTH10-7-F directly replace the KSC1730YTA in a through-hole application?

A: No. The MMBTH10-7-F uses surface-mount SOT-23-3 packaging, while the KSC1730YTA uses through-hole TO-92-3 packaging. Direct board-level substitution is not possible without circuit board redesign and component placement modification.

Q: Why do the Infineon BFP series parts have lower voltage ratings than the KSC1730YTA?

A: The BFP420H6740XTSA1, BFP520H6327XTSA1, and BFP840FESDH6327XTSA1 are optimized for higher-frequency RF applications (25GHz, 45GHz, and 85GHz respectively) rather than voltage performance. Lower voltage ratings reflect design trade-offs for improved high-frequency characteristics. Selection depends on whether the application requires the full 15V voltage capability or can operate at reduced voltages.

Q: Is the BFU690F,115 suitable for applications requiring the full 15V rating of the KSC1730YTA?

A: No. The BFU690F,115 has a maximum collector-emitter breakdown voltage of 5.5V, which is insufficient for circuits designed for 15V operation. This part is suitable only for applications that can operate at 5.5V or lower.

Q: What is the primary advantage of the PH1090-350L over the KSC1730YTA?

A: The PH1090-350L is designed for high-power RF applications, providing 350W maximum power dissipation and 17A maximum collector current compared to the KSC1730YTA's 250mW and 50mA. However, it uses chassis-mount packaging and is not suitable for small-signal RF circuits.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All active substitute parts listed (MMBTH10-7-F, BFU690F,115, BFP420H6740XTSA1, BFP520H6327XTSA1, BFP840FESDH6327XTSA1, and PH1090-350L) are ROHS3 compliant. The KSC1730YTA's RoHS status is not specified in the provided data.

Q: Which substitute part most closely matches the electrical specifications of the KSC1730YTA?

A: The MMBTH10-7-F provides the closest match in terms of collector current (50mA), power dissipation (300mW), and operating temperature (150°C). However, it has lower transition frequency (650MHz vs. 1.1GHz) and higher voltage rating (25V vs. 15V). The primary limitation is packaging format (surface-mount vs. through-hole).

Q: Can I use a higher-frequency part like the BFP840FESDH6327XTSA1 in place of the KSC1730YTA?

A: Higher-frequency parts can be used in lower-frequency applications, but circuit performance and stability must be verified. The BFP840FESDH6327XTSA1's 85GHz transition frequency, lower voltage rating (2.6V), and reduced power dissipation (75mW) may introduce design complications. Surface-mount packaging also requires board redesign.

Q: What is the moisture sensitivity level (MSL) for all parts?

A: All parts listed, including the KSC1730YTA and all substitutes, have MSL 1 (Unlimited), indicating no moisture sensitivity restrictions during storage and handling.

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