MPSW42 Equivalent & Substitute Parts

Part Overview

The MPSW42 is an NPN bipolar junction transistor (BJT) manufactured by onsemi, rated for 300 V collector-emitter breakdown voltage and 500 mA maximum collector current in a Through Hole TO-92 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The MPSW42 is suitable for general-purpose switching and amplification applications requiring moderate voltage and current ratings.

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
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 30mA, 10V	—
Power - Max	1	W
Frequency - Transition	50	MHz
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—

Substitute Part Grouping Explanation

Substitution of the MPSW42 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor Type: NPN configuration required
Voltage - Collector Emitter Breakdown (Max): Minimum 300 V
Current - Collector (Ic) (Max): Minimum 500 mA
DC Current Gain (hFE): Minimum 40 @ 30mA, 10V
Vce Saturation: Maximum 500mV @ 2mA, 20mA
Frequency - Transition: Minimum 50 MHz
Operating Temperature: Must encompass -55°C to 150°C or higher

Mechanical Compatibility Criteria:

Mounting Type: Through Hole
Package / Case: TO-92-3 or TO-92 compatible form factor

Substitute parts are grouped into two categories: Direct Electrical Equivalents (matching all primary electrical specifications within tolerance) and Enhanced Performance Alternatives (exceeding one or more electrical parameters while maintaining backward compatibility).

Parameter Comparison

Parameter	MPSW42	KSP42BU	MPSA42	ZTX857
Manufacturer	onsemi	onsemi	Diotec Semiconductor	Diodes Incorporated
Transistor Type	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	300 V	300 V	300 V	300 V
Current - Collector (Ic) (Max)	500 mA	500 mA	500 mA	3 A
Vce Saturation (Max) @ Ib, Ic	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA	250mV @ 600mA, 3A
Current - Collector Cutoff (Max)	100nA	100nA	100nA	50nA
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 30mA, 10V	40 @ 30mA, 10V	40 @ 30mA, 10V	100 @ 500mA, 10V
Power - Max	1 W	625 mW	625 mW	1.2 W
Frequency - Transition	50 MHz	50 MHz	50 MHz	80 MHz
Operating Temperature Range	-55 to 150°C	Up to 150°C	-55 to 150°C	-55 to 200°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3	E-Line-3 (TO-92 compatible)
Product Status	Obsolete	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	Not applicable	ROHS3 Compliant

Engineering Selection Recommendations

KSP42BU (onsemi) is the primary direct electrical equivalent to the MPSW42. Both devices share identical electrical specifications across voltage, current, gain, and saturation parameters. The KSP42BU is manufactured by the same supplier (onsemi) and maintains active product status with ROHS3 compliance. The primary difference is reduced maximum power dissipation (625 mW versus 1 W), which is acceptable for applications not requiring the full 1 W power budget. The KSP42BU is suitable for direct replacement in existing designs.

MPSA42 (Diotec Semiconductor) provides electrical equivalence with identical voltage, current, and gain specifications. This device maintains the full operating temperature range (-55°C to 150°C) and is available in active production. MPSA42 exhibits reduced maximum power dissipation (625 mW) similar to KSP42BU. RoHS compliance status is not applicable for this device. MPSA42 is suitable for applications where the reduced power rating does not constrain circuit operation.

ZTX857 (Diodes Incorporated) represents an enhanced performance alternative with superior electrical characteristics. This device exceeds the MPSW42 specification in collector current (3 A versus 500 mA), power dissipation (1.2 W versus 1 W), transition frequency (80 MHz versus 50 MHz), and operating temperature range (-55°C to 200°C). The ZTX857 maintains the required 300 V breakdown voltage and exhibits improved saturation characteristics (250mV at higher current levels). The ZTX857 is ROHS3 compliant and active in production. This device is suitable for applications requiring higher current capacity or extended temperature operation, provided circuit design accommodates the enhanced performance parameters.

For applications requiring RoHS3 compliance, KSP42BU or ZTX857 are specified selections. For applications with no compliance requirement, MPSA42 provides an alternative. All three substitute parts are in active production, ensuring supply continuity beyond the obsolete MPSW42.

Frequently Asked Questions (FAQ)

Q: Can KSP42BU directly replace MPSW42 in all applications?

A: KSP42BU is electrically equivalent to MPSW42 across all primary specifications (voltage, current, gain, saturation). The reduced maximum power dissipation (625 mW versus 1 W) requires verification that circuit power requirements do not exceed 625 mW. If the application operates within this power envelope, direct substitution is valid. Mechanical compatibility is confirmed; both use TO-92-3 packaging.

Q: What is the difference between MPSA42 and KSP42BU?

A: Both devices provide identical electrical specifications matching MPSW42 requirements. The primary difference is manufacturer: MPSA42 is supplied by Diotec Semiconductor, while KSP42BU is supplied by onsemi. Both exhibit 625 mW maximum power dissipation. KSP42BU carries ROHS3 compliance certification; MPSA42 RoHS status is not applicable. Selection between these devices depends on supply chain availability and compliance requirements.

Q: When should ZTX857 be selected instead of KSP42BU or MPSA42?

A: ZTX857 is selected when circuit requirements exceed MPSW42 baseline specifications. Applications requiring collector currents above 500 mA, power dissipation above 1 W, transition frequencies above 50 MHz, or operating temperatures above 150°C benefit from ZTX857 enhanced performance. The device maintains backward compatibility with MPSW42 electrical requirements while providing additional performance margin. ZTX857 is suitable for high-reliability applications and designs requiring extended temperature operation.

Q: Are all substitute parts mechanically compatible with MPSW42 PCB layouts?

A: KSP42BU and MPSA42 use standard TO-92-3 packaging, providing direct mechanical compatibility with MPSW42 footprints. ZTX857 uses E-Line-3 packaging, which is TO-92 compatible but may exhibit minor dimensional variations. Verification of PCB footprint dimensions is recommended for ZTX857 integration, particularly for high-density layouts or automated assembly processes.

Q: What compliance certifications apply to each substitute part?

A: KSP42BU and ZTX857 are ROHS3 compliant. MPSA42 RoHS compliance status is not applicable. All three devices are REACH unaffected and classified under ECCN EAR99. For applications requiring RoHS3 certification, KSP42BU or ZTX857 are specified selections.

Q: Can MPSW42 be used interchangeably with these substitutes in reverse?

A: No. MPSW42 is classified as obsolete and is not recommended for new designs. Existing designs using MPSW42 should transition to active production alternatives (KSP42BU, MPSA42, or ZTX857) to ensure long-term supply continuity and compliance with current regulatory standards.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message