MPS4124RLRAG Equivalent & Substitute Parts

Part Overview

The MPS4124RLRAG is an NPN bipolar junction transistor manufactured by onsemi, rated for 25 V collector-emitter breakdown voltage and 200 mA maximum collector current. The device is packaged in a through-hole TO-92 (TO-226-3) configuration with a maximum power dissipation of 625 mW and transition frequency of 170 MHz. The MPS4124RLRAG is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain electrical compatibility within the specified parameter ranges while accommodating different packaging and mounting technologies.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	25	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	625	mW
Frequency - Transition	170	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	120 @ 2mA, 1V	—
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 50mA	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-226-3, TO-92-3	—

Substitute Part Grouping Explanation

Substitution of the MPS4124RLRAG is determined by the following critical electrical parameters: NPN transistor type, 25 V maximum collector-emitter breakdown voltage, and 200 mA maximum collector current rating. The DC current gain minimum of 120 at specified conditions and saturation voltage characteristics establish the baseline performance envelope. Substitute parts are grouped into two categories based on mounting technology:

Category 1: Surface Mount Equivalent — Parts maintaining identical electrical specifications with surface-mount packaging (SOT-23-3). These substitutes provide direct functional replacement for applications where PCB layout permits surface-mount technology.

Category 2: Through-Hole Higher-Current Alternatives — Parts maintaining the 25 V voltage rating and through-hole mounting but with higher current ratings (2 A to 4 A). These substitutes accommodate applications requiring greater collector current capacity while preserving the through-hole form factor and mechanical compatibility with existing PCB designs.

The critical parameters governing substitution are: transistor type (NPN), maximum collector-emitter breakdown voltage (25 V minimum), maximum collector current (200 mA minimum), and operating temperature range (-55°C to 150°C minimum).

Parameter Comparison

Parameter	MPS4124RLRAG	MMBT4124LT1G	ZTX1049ASTZ	ZTX649STZ
Manufacturer	onsemi	onsemi	Diodes Incorporated	Diodes Incorporated
Transistor Type	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	25 V	25 V	25 V	25 V
Current - Collector (Ic) (Max)	200 mA	200 mA	4 A	2 A
Power - Max	625 mW	225 mW	1 W	1 W
Frequency - Transition	170 MHz	300 MHz	180 MHz	240 MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	120 @ 2mA, 1V	120 @ 2mA, 1V	300 @ 1A, 2V	100 @ 1A, 2V
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	220mV @ 50mA, 4A	500mV @ 200mA, 2A
Current - Collector Cutoff (Max)	50nA (ICBO)	50nA (ICBO)	10nA	100nA (ICBO)
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 200°C	-55 to 200°C
Mounting Type	Through Hole	Surface Mount	Through Hole	Through Hole
Package / Case	TO-226-3, TO-92-3	TO-236-3, SOT-23-3	E-Line-3	E-Line-3
Product Status	Obsolete	Active	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

MMBT4124LT1G is the direct electrical equivalent of the MPS4124RLRAG, maintaining identical collector current (200 mA), collector-emitter breakdown voltage (25 V), DC current gain (120 @ 2mA, 1V), and saturation voltage characteristics (300mV @ 5mA, 50mA). The MMBT4124LT1G is manufactured by onsemi and carries Active product status with ROHS3 compliance, providing long-term availability and regulatory alignment. The primary design consideration is the transition from through-hole TO-92 packaging to surface-mount SOT-23-3 packaging, which requires PCB layout modification. This substitute is appropriate for new designs or redesigns where surface-mount technology is acceptable.

ZTX1049ASTZ and ZTX649STZ are higher-current alternatives manufactured by Diodes Incorporated, both rated for 25 V collector-emitter breakdown voltage and through-hole E-Line mounting compatible with TO-92 form factor. Both devices carry Active product status and ROHS3 compliance. The ZTX1049ASTZ provides 4 A maximum collector current with 1 W power dissipation, while the ZTX649STZ provides 2 A maximum collector current with 1 W power dissipation. These substitutes are appropriate for applications requiring collector current exceeding 200 mA while maintaining through-hole mounting compatibility. The extended operating temperature range (-55°C to 200°C) provides additional thermal margin compared to the MPS4124RLRAG (-55°C to 150°C).

All substitute parts maintain REACH compliance and EAR99 export classification consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can the MMBT4124LT1G directly replace the MPS4124RLRAG in existing through-hole PCB designs?

A: The MMBT4124LT1G provides electrical equivalence but requires PCB redesign due to packaging differences. The MPS4124RLRAG uses through-hole TO-92 mounting with formed leads, while the MMBT4124LT1G uses surface-mount SOT-23-3 packaging. Mechanical compatibility with existing through-hole footprints is not possible without PCB layout modification.

Q: What are the key electrical differences between the MPS4124RLRAG and the ZTX1049ASTZ?

A: Both devices share the 25 V collector-emitter breakdown voltage and NPN transistor type. The primary difference is collector current rating: MPS4124RLRAG is rated for 200 mA maximum, while ZTX1049ASTZ is rated for 4 A maximum. The ZTX1049ASTZ also provides higher power dissipation (1 W versus 625 mW) and extended operating temperature range (-55°C to 200°C versus -55°C to 150°C). DC current gain differs at specified test conditions: 120 @ 2mA, 1V for MPS4124RLRAG versus 300 @ 1A, 2V for ZTX1049ASTZ.

Q: Are the ZTX1049ASTZ and ZTX649STZ mechanically compatible with MPS4124RLRAG PCB footprints?

A: Both ZTX devices use E-Line-3 through-hole packaging with formed leads, which is mechanically compatible with TO-92 form factor PCB footprints. However, verification of specific lead spacing and hole diameter requirements is necessary before implementation, as E-Line packaging may have dimensional variations compared to standard TO-92.

Q: What is the significance of the transition frequency differences among these parts?

A: The MPS4124RLRAG has a transition frequency of 170 MHz, while the MMBT4124LT1G provides 300 MHz, ZTX1049ASTZ provides 180 MHz, and ZTX649STZ provides 240 MHz. Higher transition frequency indicates faster switching capability. For applications operating below 170 MHz, all substitutes are suitable. For applications requiring specific frequency response characteristics, the transition frequency specification must be verified against circuit requirements.

Q: Why is the MPS4124RLRAG classified as obsolete?

A: The MPS4124RLRAG is listed as obsolete by the manufacturer. Active alternatives with equivalent or superior electrical specifications are available from onsemi (MMBT4124LT1G) and Diodes Incorporated (ZTX1049ASTZ, ZTX649STZ), all carrying Active product status and current manufacturing support.

Q: Are all substitute parts RoHS3 compliant?

A: The MMBT4124LT1G, ZTX1049ASTZ, and ZTX649STZ are all ROHS3 compliant. The original MPS4124RLRAG RoHS status is not specified in the provided data. All parts maintain REACH compliance.

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