KSC1393RBU Equivalent & Substitute Parts

Part Overview

The KSC1393RBU is an RF transistor manufactured by onsemi, classified as an NPN bipolar junction transistor (BJT) designed for RF applications. This component operates at a maximum collector-emitter breakdown voltage of 30V with a transition frequency of 700MHz and maximum power dissipation of 250mW. The device is packaged in a through-hole TO-92-3 configuration.

The KSC1393RBU is currently listed as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support legacy system maintenance or redesign efforts where component sourcing becomes critical.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	30V	V
Frequency - Transition	700MHz	MHz
Power - Max	250mW	mW
Current - Collector (Ic) (Max)	20mA	mA
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 2mA, 10V	—
Noise Figure (dB Typ @ f)	2dB ~ 3dB @ 200MHz	dB
Gain	20dB ~ 24dB	dB
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 KSC1393RBU requires evaluation based on the following critical parameters:

Transistor Type: All substitutes must be NPN bipolar junction transistors to maintain circuit polarity and biasing compatibility.

Voltage Rating: The collector-emitter breakdown voltage must equal or exceed 30V to ensure safe operation within the original design envelope.

Frequency Performance: The transition frequency must support the 700MHz operating band. Higher frequency capability provides margin but does not compromise functionality.

Power Dissipation: Maximum power rating must accommodate the 250mW specification to prevent thermal stress.

Current Handling: Maximum collector current must support the 20mA requirement.

Mounting Type and Package: Physical form factor determines PCB integration method. Through-hole packages (TO-92-3) differ fundamentally from surface-mount packages (SOT-343, etc.), requiring circuit board redesign if substitution involves package type change.

Gain and Noise Figure: These parameters define RF performance characteristics and must remain within acceptable ranges for the intended application.

The substitute parts listed below are evaluated against these criteria.

Parameter Comparison

Parameter	KSC1393RBU (Main)	BFP420H6327XTSA1	MAPR-000912-500S00
Manufacturer	onsemi	Infineon Technologies	MACOM Technology Solutions
Transistor Type	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	30V	5V	80V
Frequency - Transition	700MHz	25GHz	—
Power - Max	250mW	160mW	500W
Current - Collector (Ic) (Max)	20mA	35mA	52.5A
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 2mA, 10V	60 @ 20mA, 4V	—
Noise Figure (dB Typ @ f)	2dB ~ 3dB @ 200MHz	1.1dB @ 1.8GHz	—
Gain	20dB ~ 24dB	21dB	9.44dB ~ 9.77dB
Operating Temperature (TJ)	150°C	150°C	200°C
Mounting Type	Through Hole	Surface Mount	Chassis Mount
Package / Case	TO-92-3	SOT-343	—
Product Status	Obsolete	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

BFP420H6327XTSA1 (Infineon Technologies):

This substitute is an active product with ROHS3 compliance. However, critical parameter mismatches exist. The collector-emitter breakdown voltage is 5V, which is insufficient for the 30V design specification of the KSC1393RBU. This part cannot be used as a direct substitute in circuits requiring 30V operation. Additionally, the BFP420H6327XTSA1 uses surface-mount SOT-343 packaging, requiring PCB redesign from the original through-hole TO-92-3 layout. The higher transition frequency (25GHz) and improved noise figure (1.1dB @ 1.8GHz) provide performance margin but do not offset the voltage rating deficiency.

MAPR-000912-500S00 (MACOM Technology Solutions):

This substitute is an active product with ROHS3 compliance and operates at a higher collector-emitter breakdown voltage of 80V, exceeding the 30V requirement. However, this part is designed for high-power chassis-mount applications with 500W power dissipation and 52.5A collector current capability. These specifications represent a significant over-design for the 250mW, 20mA KSC1393RBU application. The transition frequency is not specified, and the gain specification (9.44dB ~ 9.77dB) is substantially lower than the KSC1393RBU (20dB ~ 24dB). The mounting type is chassis mount, incompatible with the original through-hole PCB integration. This part is suitable only for high-power RF applications fundamentally different from the KSC1393RBU design envelope.

Substitution Feasibility:

Neither listed substitute part provides a direct functional replacement for the KSC1393RBU within its original design specifications. The BFP420H6327XTSA1 fails the voltage requirement. The MAPR-000912-500S00 is over-specified for power and current, with incompatible mounting and reduced gain. Both require significant circuit redesign.

For applications requiring the KSC1393RBU, alternative strategies include: sourcing remaining inventory from authorized distributors, evaluating other NPN RF transistors with matching 30V voltage rating and 700MHz frequency capability, or redesigning the circuit to accommodate available active substitutes with appropriate parameter matching.

Frequently Asked Questions (FAQ)

Q: Can the BFP420H6327XTSA1 replace the KSC1393RBU in a 30V circuit?

A: No. The BFP420H6327XTSA1 has a maximum collector-emitter breakdown voltage of 5V. Operating this device at 30V will cause immediate failure. This part is not suitable for circuits designed for the KSC1393RBU's 30V specification.

Q: What is the primary limitation of the MAPR-000912-500S00 as a substitute?

A: The MAPR-000912-500S00 is designed for high-power applications (500W, 52.5A) and uses chassis-mount packaging. It is fundamentally incompatible with the KSC1393RBU's low-power (250mW, 20mA) through-hole design. Additionally, the gain specification is significantly lower, making it unsuitable for RF amplification circuits requiring the KSC1393RBU's 20dB ~ 24dB gain range.

Q: Does the higher transition frequency of the BFP420H6327XTSA1 (25GHz vs. 700MHz) make it suitable for the KSC1393RBU application?

A: Higher transition frequency alone does not compensate for the 5V voltage rating limitation. While the BFP420H6327XTSA1 offers superior frequency performance, it cannot operate safely at the 30V collector-emitter voltage required by the original design.

Q: What mounting considerations apply when evaluating substitutes?

A: The KSC1393RBU uses through-hole TO-92-3 packaging for direct PCB insertion. The BFP420H6327XTSA1 requires surface-mount soldering (SOT-343), and the MAPR-000912-500S00 uses chassis mounting. Any substitute with different packaging requires PCB layout redesign and assembly process changes.

Q: Are there compliance advantages to using the active substitute parts?

A: Both BFP420H6327XTSA1 and MAPR-000912-500S00 are ROHS3 compliant active products, whereas the KSC1393RBU is obsolete. However, compliance status does not override fundamental electrical parameter mismatches. Substitution must prioritize electrical compatibility before considering compliance benefits.

Q: What should be done if the KSC1393RBU is no longer available?

A: Evaluate alternative NPN RF transistors with matching specifications: 30V minimum collector-emitter breakdown voltage, 700MHz or higher transition frequency, 250mW or higher power rating, and 20mA or higher collector current capability. Verify that gain and noise figure specifications align with the original circuit requirements. Consider whether circuit redesign to accommodate available active substitutes is feasible for the application.

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