MPSA43 Equivalent & Substitute Parts

Part Overview

The MPSA43 is an NPN bipolar junction transistor manufactured by onsemi, designed for small-signal switching and amplification applications. The device features a 200 V collector-emitter breakdown voltage rating and supports collector currents up to 500 mA, with a maximum power dissipation of 625 mW in a Through Hole TO-92 package.

The MPSA43 is classified as obsolete. Locating equivalent substitute parts is necessary to maintain design continuity and ensure component availability for new production builds, repairs, and system upgrades where this transistor was originally specified.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	200	V
Current - Collector (Ic) (Max)	500	mA
Power - Max	625	mW
Frequency - Transition	50	MHz
Vce Saturation (Max) @ Ib, Ic	500mV @ 2mA, 20mA	V
Current - Collector Cutoff (Max)	100	nA
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
Operating Temperature Range	-55 to 150	°C

Substitute Part Grouping Explanation

Substitution of the MPSA43 is determined by strict equivalence across the following electrical and mechanical parameters:

Critical Matching Parameters:

Transistor Type: NPN configuration
Voltage - Collector Emitter Breakdown (Max): 200 V
Current - Collector (Ic) (Max): 500 mA
Power - Max: 625 mW
Frequency - Transition: 50 MHz
Vce Saturation (Max) @ Ib, Ic: 500mV @ 2mA, 20mA
Current - Collector Cutoff (Max): 100 nA
Mounting Type: Through Hole
Package / Case: TO-92-3

The KSP43BU manufactured by Fairchild Semiconductor meets all critical electrical specifications and mechanical package requirements, establishing it as a direct functional equivalent to the MPSA43.

Parameter Comparison

Parameter	MPSA43 (onsemi)	KSP43BU (Fairchild Semiconductor)	Match Status
Transistor Type	NPN	NPN	Equivalent
Voltage - Collector Emitter Breakdown (Max)	200 V	200 V	Equivalent
Current - Collector (Ic) (Max)	500 mA	500 mA	Equivalent
Power - Max	625 mW	625 mW	Equivalent
Frequency - Transition	50 MHz	50 MHz	Equivalent
Vce Saturation (Max) @ Ib, Ic	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA	Equivalent
Current - Collector Cutoff (Max)	100 nA	100 nA	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Package / Case	TO-92-3	TO-92-3	Equivalent
Operating Temperature Range	-55 to 150 °C	Up to 150 °C	Compatible
DC Current Gain (hFE) (Min) @ Ic, Vce	25 @ 1mA, 10V	40 @ 30mA, 10V	KSP43BU higher at specified test point
Product Status	Obsolete	Active	Substitute is in active production

Engineering Selection Recommendations

The KSP43BU is a direct electrical and mechanical equivalent to the MPSA43 across all critical parameters. The substitute part is manufactured by Fairchild Semiconductor and maintains active product status, ensuring ongoing availability and supply chain continuity.

The KSP43BU demonstrates a higher DC current gain (hFE) of 40 @ 30mA, 10V compared to the MPSA43 specification of 25 @ 1mA, 10V. This difference reflects measurement at different test conditions and does not preclude substitution; both devices operate within the small-signal transistor classification and are suitable for identical circuit applications.

Both parts share identical electrical ratings for breakdown voltage, maximum collector current, power dissipation, transition frequency, saturation voltage, and cutoff current. The TO-92-3 package pinout and Through Hole mounting type are identical, enabling direct board-level replacement without circuit modification or PCB redesign.

The MPSA43 is RoHS non-compliant, while compliance status for the KSP43BU is not specified in the provided data. For applications requiring RoHS compliance certification, component documentation from the supplier must be consulted.

Frequently Asked Questions (FAQ)

Q: Can the KSP43BU replace the MPSA43 in existing circuit designs?

A: Yes. The KSP43BU meets all electrical specifications and mechanical package requirements of the MPSA43. Direct substitution is supported without circuit modification.

Q: Are the pin configurations identical between MPSA43 and KSP43BU?

A: Yes. Both devices use the TO-92-3 package with identical pinout configuration, enabling direct board-level replacement.

Q: What is the significance of the different DC current gain (hFE) values?

A: The hFE values are measured at different test conditions. MPSA43 specifies 25 @ 1mA, 10V while KSP43BU specifies 40 @ 30mA, 10V. Both values fall within acceptable ranges for small-signal transistor applications and do not prevent substitution.

Q: Is the KSP43BU available in the same Through Hole package?

A: Yes. The KSP43BU is supplied in the TO-92-3 Through Hole package, identical to the MPSA43.

Q: Why is the MPSA43 classified as obsolete?

A: The MPSA43 is no longer in active production by onsemi. The KSP43BU, maintained in active production status by Fairchild Semiconductor, provides equivalent functionality and ensures component availability.

Q: What are the maximum operating temperature limits for each part?

A: The MPSA43 operates from -55°C to 150°C. The KSP43BU operates up to 150°C. For applications requiring the full -55°C lower temperature range, the KSP43BU specification should be confirmed with the manufacturer.

Q: Are there any compliance differences between the two parts?

A: The MPSA43 is RoHS non-compliant. Compliance status for the KSP43BU is not specified in the provided technical data. Consult supplier documentation for RoHS and other regulatory compliance requirements.

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