KSC3503ESTU Equivalent & Substitute Parts

Part Overview

The KSC3503ESTU is a through-hole NPN bipolar junction transistor manufactured by onsemi, rated for 300 V collector-emitter breakdown voltage and 100 mA maximum collector current. This device is designed for general-purpose switching and amplification applications requiring moderate voltage and current handling capabilities. The KSC3503ESTU is classified as obsolete, necessitating identification of active equivalent parts for new designs and ongoing production requirements. Substitute parts must maintain electrical and mechanical compatibility across all critical performance parameters.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	100	mA
Power - Max	7	W
Frequency - Transition	150	MHz
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—
Vce Saturation (Max)	600 mV @ 2 mA, 20 mA	—
Current - Collector Cutoff (Max)	100	nA

Substitute Part Grouping Explanation

Substitution of the KSC3503ESTU is determined by strict equivalence across the following electrical and mechanical parameters:

Electrical Equivalence Criteria:

Transistor type must be NPN
Voltage - Collector Emitter Breakdown (Max) must equal 300 V
Current - Collector (Ic) (Max) must equal 100 mA
Power - Max must equal 7 W
Frequency - Transition must equal 150 MHz
Operating Temperature Range must span -55°C to 150°C
Vce Saturation (Max) must equal 600 mV @ 2 mA, 20 mA
Current - Collector Cutoff (Max) must equal 100 nA

Mechanical Equivalence Criteria:

Mounting Type must be Through Hole
Package / Case must be TO-126-3

The KSC3503DSTU meets all electrical and mechanical equivalence criteria and is identified as a direct substitute. DC Current Gain (hFE) variation does not preclude substitution when all other parameters remain within specification.

Parameter Comparison

Parameter	KSC3503ESTU	KSC3503DSTU	Unit
Manufacturer	onsemi	onsemi	—
Transistor Type	NPN	NPN	—
Voltage - Collector Emitter Breakdown (Max)	300	300	V
Current - Collector (Ic) (Max)	100	100	mA
Vce Saturation (Max) @ Ib, Ic	600 mV @ 2 mA, 20 mA	600 mV @ 2 mA, 20 mA	—
Current - Collector Cutoff (Max)	100	100	nA
Power - Max	7	7	W
Frequency - Transition	150	150	MHz
Operating Temperature	-55 to 150	-55 to 150	°C
Mounting Type	Through Hole	Through Hole	—
Package / Case	TO-126-3	TO-126-3	—
Product Status	Obsolete	Active	—

Engineering Selection Recommendations

The KSC3503DSTU is the direct electrical and mechanical equivalent of the KSC3503ESTU. Both parts are manufactured by onsemi and share identical electrical specifications across all critical parameters. The primary distinction is product status: the KSC3503ESTU is obsolete, while the KSC3503DSTU is active.

For new designs and production applications, the KSC3503DSTU is the appropriate selection. This part maintains full compatibility with existing circuit designs specified for the KSC3503ESTU while ensuring ongoing availability and manufacturer support. The KSC3503DSTU carries RoHS3 compliance certification, meeting current regulatory requirements for electronic components in restricted substance directives.

Both parts are REACH Unaffected and classified under ECCN EAR99, with identical HTSUS coding (8541.29.0075). Packaging differs between the two variants: the KSC3503ESTU is supplied in standard packaging, while the KSC3503DSTU is supplied in tube packaging. This packaging difference does not affect electrical performance or mechanical fit within TO-126-3 footprints.

Frequently Asked Questions (FAQ)

Q: Can the KSC3503DSTU directly replace the KSC3503ESTU in existing designs?

A: Yes. The KSC3503DSTU is electrically and mechanically equivalent to the KSC3503ESTU. All critical electrical parameters—voltage rating, current rating, power dissipation, frequency response, and saturation characteristics—are identical. Both devices use the TO-126-3 package and through-hole mounting. Direct substitution is supported without circuit modification.

Q: What is the difference between the KSC3503ESTU and KSC3503DSTU?

A: The primary difference is product status. The KSC3503ESTU is obsolete, while the KSC3503DSTU is active. The KSC3503DSTU also carries RoHS3 compliance certification. Packaging format differs: the KSC3503ESTU uses standard packaging, and the KSC3503DSTU uses tube packaging. Electrical specifications are identical.

Q: Are there DC Current Gain (hFE) differences between these parts?

A: Yes. The KSC3503ESTU specifies a minimum DC Current Gain of 100 @ 10 mA, 10 V, while the KSC3503DSTU specifies a minimum of 40 @ 10 mA, 10 V. Both values fall within acceptable operating ranges for general-purpose switching applications. Circuit designs should account for hFE variation through appropriate base current biasing to ensure reliable operation across the specified gain range.

Q: Is the TO-126-3 package compatible with TO-225AA references?

A: The KSC3503ESTU and KSC3503DSTU are listed with both TO-225AA and TO-126-3 package designations. The supplier device package for both parts is TO-126-3. Designs should reference the TO-126-3 specification for mechanical and electrical compatibility.

Q: What is the operating temperature range for these transistors?

A: Both the KSC3503ESTU and KSC3503DSTU operate across a junction temperature range of -55°C to 150°C. This range supports applications in industrial, automotive, and consumer electronics environments requiring extended temperature performance.

Q: Are these parts suitable for high-frequency switching applications?

A: Both parts feature a transition frequency of 150 MHz, supporting switching applications up to this frequency limit. Applications requiring higher frequency response require alternative device selection.

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