MPSA42_D75Z Equivalent & Substitute Parts

Part Overview

The MPSA42_D75Z is an NPN bipolar junction transistor manufactured by onsemi, rated for 300 V collector-emitter breakdown voltage and 500 mA maximum collector current. This device is packaged in TO-92-3 (TO-226AA) through-hole configuration with a maximum power dissipation of 625 mW and transition frequency of 50 MHz. The part is classified as obsolete, making equivalent and substitute components necessary for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility across critical parameters including voltage rating, current capacity, gain characteristics, and thermal operating range.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	500	mA
Vce Saturation (Max) @ Ib, Ic	500mV @ 2mA, 20mA	V
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 30mA, 10V	—
Power - Max	625	mW
Frequency - Transition	50	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—

Substitute Part Grouping Explanation

Substitute parts for the MPSA42_D75Z are classified into two categories based on electrical and mechanical compatibility:

Parametric Equivalents maintain identical electrical specifications across all critical parameters: 300 V breakdown voltage, 500 mA collector current, 625 mW power dissipation, 50 MHz transition frequency, and matching saturation voltage characteristics. These parts are direct functional replacements with no circuit redesign required.

Similar Parts share the core electrical ratings (300 V breakdown, 500 mA collector current) but differ in one or more secondary parameters such as transition frequency, power dissipation, saturation voltage, or operating temperature range. These parts are suitable for applications where the specific parameter differences do not conflict with circuit requirements.

The substitution logic is based strictly on the following key parameters:

Voltage - Collector Emitter Breakdown (Max): minimum 300 V
Current - Collector (Ic) (Max): minimum 500 mA
Transistor Type: NPN
Mounting Type: Through Hole
Package compatibility: TO-92-3 or TO-92 compatible

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce Breakdown (Max) V	Power (Max) mW	Frequency (Transition) MHz	Operating Temp °C	Package	Vce Sat (Max) mV
MPSA42_D75Z	onsemi	Obsolete	500	300	625	50	-55 to 150	TO-92-3	500
KSP42TA	onsemi	Active	500	300	625	50	-55 to 150	TO-92-3	500
MPSA42	Diotec Semiconductor	Active	500	300	625	50	-55 to 150	TO-92-3	500
ZTX457STZ	Diodes Incorporated	Active	500	300	1000	75	-55 to 200	E-Line (TO-92 compatible)	300
ZTX657	Diodes Incorporated	Active	500	300	1000	30	-55 to 200	E-Line (TO-92 compatible)	500
ZTX657STZ	Diodes Incorporated	Active	500	300	1000	30	-55 to 200	E-Line (TO-92 compatible)	500
ZTX658STZ	Diodes Incorporated	Active	500	400	1000	50	-55 to 200	E-Line (TO-92 compatible)	500

Engineering Selection Recommendations

Parametric Equivalents (Direct Replacements)

KSP42TA (onsemi) and MPSA42 (Diotec Semiconductor) are parametric equivalents to the MPSA42_D75Z. Both parts maintain identical electrical specifications across all critical parameters and are classified as active products. KSP42TA is available in cut tape packaging with 55,300 units in stock and carries ROHS3 compliance. MPSA42 from Diotec is available in cut tape packaging with 27,010 units in stock. Both parts are suitable for direct substitution without circuit modification.

Similar Parts (Application-Dependent Selection)

ZTX457STZ (Diodes Incorporated) offers enhanced performance characteristics including 1 W power dissipation (versus 625 mW), 75 MHz transition frequency (versus 50 MHz), and extended operating temperature range to 200°C. The saturation voltage is reduced to 300 mV at specified conditions. This part is suitable for applications requiring higher frequency response or thermal margin.

ZTX657 and ZTX657STZ (Diodes Incorporated) maintain the 300 V breakdown voltage and 500 mA current rating with 1 W power dissipation and extended temperature range to 200°C. The transition frequency is 30 MHz, lower than the original specification. These parts are suitable for applications where frequency requirements are less stringent and additional thermal headroom is beneficial.

ZTX658STZ (Diodes Incorporated) provides 400 V breakdown voltage (versus 300 V), 1 W power dissipation, and 50 MHz transition frequency matching the original part. This part is suitable for applications requiring higher voltage margin while maintaining frequency characteristics.

All substitute parts are through-hole mounted and compatible with TO-92-3 or TO-92 compatible footprints. Selection should be based on specific application requirements for voltage rating, frequency response, power dissipation, and operating temperature range.

Frequently Asked Questions (FAQ)

Q: Can KSP42TA be used as a direct replacement for MPSA42_D75Z?

A: Yes. KSP42TA is a parametric equivalent with identical electrical specifications: 300 V breakdown voltage, 500 mA collector current, 625 mW power dissipation, 50 MHz transition frequency, and matching saturation voltage. The part is active and available in high volume.

Q: What is the difference between the ZTX657 and ZTX658 series?

A: The primary difference is the collector-emitter breakdown voltage. ZTX657 is rated for 300 V maximum, while ZTX658 is rated for 400 V maximum. Both maintain 500 mA collector current and 1 W power dissipation. ZTX658 is suitable for applications requiring higher voltage margin.

Q: Are the Diodes Incorporated ZTX parts pin-compatible with the MPSA42_D75Z?

A: Yes. All ZTX parts listed are through-hole mounted in E-Line (TO-92 compatible) packaging, which maintains the same pin configuration and footprint as the TO-92-3 package.

Q: Why does the MPSA42_D75Z show as obsolete?

A: The MPSA42_D75Z is classified as obsolete by onsemi. However, parametric equivalents such as KSP42TA (onsemi) and MPSA42 (Diotec Semiconductor) are active products with identical specifications and are recommended for new designs and ongoing procurement.

Q: Can ZTX457STZ be used in place of MPSA42_D75Z?

A: ZTX457STZ is a similar part with enhanced specifications. It maintains the 300 V breakdown voltage and 500 mA current rating but offers higher transition frequency (75 MHz versus 50 MHz), higher power dissipation (1 W versus 625 mW), and extended operating temperature range (-55°C to 200°C versus -55°C to 150°C). It is suitable for applications where these enhancements do not conflict with circuit design.

Q: What compliance certifications apply to the substitute parts?

A: KSP42TA carries ROHS3 compliance. MPSA42 from Diotec does not have RoHS status listed. All Diodes Incorporated parts (ZTX457STZ, ZTX657, ZTX657STZ, ZTX658STZ) carry ROHS3 compliance. All parts listed are REACH unaffected and classified as EAR99 for export control purposes.

Q: Are there packaging differences between substitute parts?

A: Yes. KSP42TA is supplied in cut tape (CT) packaging. MPSA42 from Diotec is supplied in cut tape (CT) packaging. ZTX457STZ is supplied in cut tape (CT) packaging. ZTX657 is supplied in bulk packaging. ZTX657STZ and ZTX658STZ are supplied in tape and box (TB) packaging. All parts are through-hole mounted and compatible with standard TO-92-3 footprints.

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