ZTX458STZ Equivalent & Substitute Parts

Part Overview

The ZTX458STZ is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for general-purpose switching and amplification applications. This through-hole component operates at 400 V collector-emitter breakdown voltage with a maximum collector current of 300 mA and 1 W power dissipation capability. The device is classified as Active product status with full RoHS3 compliance and REACH unaffected designation. Substitute parts are identified when equivalent electrical performance parameters and mechanical compatibility are required due to component availability, supply chain considerations, or design flexibility within specified operational limits.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	400	V
Current - Collector (Ic) (Max)	300	mA
Power - Max	1	W
Mounting Type	Through Hole	—
Package / Case	E-Line-3, Formed Leads	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the ZTX458STZ are qualified based on the following electrical and mechanical parameters:

Critical Matching Parameters:

Transistor Type: NPN configuration
Voltage - Collector Emitter Breakdown (Max): 400 V minimum
Current - Collector (Ic) (Max): 300 mA minimum
Mounting Type: Through Hole
RoHS Status: ROHS3 Compliant

The substitute parts KSP44TA and KSP44TF, both manufactured by onsemi, satisfy these core requirements. Both devices operate at 400 V breakdown voltage with 300 mA maximum collector current and through-hole mounting configuration. Both are ROHS3 compliant and maintain Active product status. The substitute parts are packaged in TO-92-3 format, which is mechanically compatible with E-Line-3 through-hole applications.

Parameter Comparison

Parameter	ZTX458STZ (Diodes Inc.)	KSP44TA (onsemi)	KSP44TF (onsemi)
Transistor Type	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	400 V	400 V	400 V
Current - Collector (Ic) (Max)	300 mA	300 mA	300 mA
Power - Max	1 W	625 mW	625 mW
Vce Saturation (Max) @ Ib, Ic	500mV @ 6mA, 50mA	750mV @ 5mA, 50mA	750mV @ 5mA, 50mA
Current - Collector Cutoff (Max)	100nA	500nA	500nA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 50mA, 10V	50 @ 10mA, 10V	50 @ 10mA, 10V
Frequency - Transition	50MHz	—	—
Operating Temperature (TJ)	-55°C ~ 200°C	150°C	150°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	E-Line-3, Formed Leads	TO-92-3 (TO-226AA) Formed Leads	TO-92-3 (TO-226AA) Formed Leads
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active

Engineering Selection Recommendations

Both KSP44TA and KSP44TF qualify as equivalent substitutes for the ZTX458STZ based on matching electrical specifications for voltage and current ratings. All three devices maintain Active product status and full ROHS3 compliance, ensuring regulatory alignment and supply chain continuity.

The ZTX458STZ provides higher maximum power dissipation (1 W versus 625 mW) and extended operating temperature range (-55°C to 200°C versus 150°C maximum). Applications requiring these enhanced thermal or temperature specifications must retain the original ZTX458STZ component.

The KSP44TA and KSP44TF are functionally identical substitutes, differing only in manufacturing lot designation. Selection between these two onsemi variants is determined by inventory availability and supply chain requirements rather than electrical performance differences.

Frequently Asked Questions (FAQ)

Q: Can KSP44TA or KSP44TF be used as direct replacements for ZTX458STZ in all applications?

A: Direct substitution is valid for applications operating within the reduced power envelope (625 mW maximum) and temperature range (up to 150°C junction temperature). Applications requiring the full 1 W power capability or extended temperature operation below -55°C or above 150°C must use the original ZTX458STZ.

Q: Are the package formats compatible between ZTX458STZ and the substitute parts?

A: Yes. The ZTX458STZ E-Line-3 package and the KSP44TA/KSP44TF TO-92-3 packages are mechanically compatible for through-hole PCB mounting. Both use formed leads and occupy equivalent board space.

Q: What are the differences in DC current gain between these parts?

A: The ZTX458STZ specifies minimum hFE of 100 at 50 mA collector current and 10 V Vce. The KSP44TA and KSP44TF specify minimum hFE of 50 at 10 mA collector current and 10 V Vce. Applications dependent on higher current gain at elevated collector currents should evaluate circuit performance with the lower gain specification of the substitute parts.

Q: Do all three parts meet the same regulatory compliance standards?

A: Yes. ZTX458STZ, KSP44TA, and KSP44TF are all ROHS3 compliant and REACH unaffected, ensuring equivalent regulatory status for procurement and deployment.

Q: What is the difference between KSP44TA and KSP44TF?

A: Both parts are electrically and mechanically identical. The designation difference reflects manufacturing lot or packaging variation. Selection is based on inventory availability and supply chain logistics.

Q: Are there frequency or switching speed considerations for substitution?

A: The ZTX458STZ specifies 50 MHz transition frequency. The KSP44TA and KSP44TF do not provide transition frequency specifications in the available data. Applications requiring defined high-frequency performance should retain the ZTX458STZ or obtain detailed frequency specifications from onsemi for the substitute parts.

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