MJE700STU Equivalent & Substitute Parts

Part Overview

The MJE700STU is a PNP Darlington bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 4 A maximum collector current in a TO-126-3 through-hole package. This device is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement continuity. The MJE700STU delivers 40 W maximum power dissipation and operates at junction temperatures up to 150°C, serving applications requiring moderate-power PNP switching and amplification.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP - Darlington	—
Current - Collector (Ic) (Max)	4	A
Voltage - Collector Emitter Breakdown (Max)	60	V
Vce Saturation (Max) @ Ib, Ic	2.5V @ 30mA, 1.5A	—
Current - Collector Cutoff (Max)	100	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	750 @ 1.5A, 3V	—
Power - Max	40	W
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-225AA, TO-126-3	—

Substitute Part Grouping Explanation

Substitution of the MJE700STU is determined by electrical and mechanical parameter equivalence across the following criteria:

Electrical Parameters (Critical):

Transistor type: PNP - Darlington configuration
Maximum collector current: 4 A
Maximum collector-emitter breakdown voltage: 60 V
Maximum power dissipation: 40 W
DC current gain (hFE): minimum 750 @ 1.5A, 3V
Vce saturation: 2.5V @ 30mA, 1.5A
Operating temperature range: 150°C (TJ)

Mechanical Parameters (Critical):

Mounting type: Through Hole
Package compatibility: TO-126-3 or equivalent footprint

The BD678 manufactured by STMicroelectronics meets all specified electrical parameters and maintains through-hole mounting compatibility, qualifying it as a direct functional substitute for the obsolete MJE700STU.

Parameter Comparison

Parameter	MJE700STU (onsemi)	BD678 (STMicroelectronics)	Match
Transistor Type	PNP - Darlington	PNP - Darlington	Yes
Current - Collector (Ic) (Max)	4 A	4 A	Yes
Voltage - Collector Emitter Breakdown (Max)	60 V	60 V	Yes
Vce Saturation (Max) @ Ib, Ic	2.5V @ 30mA, 1.5A	2.5V @ 30mA, 1.5A	Yes
Current - Collector Cutoff (Max)	100 µA	500 µA	Compatible
DC Current Gain (hFE) (Min) @ Ic, Vce	750 @ 1.5A, 3V	750 @ 1.5A, 3V	Yes
Power - Max	40 W	40 W	Yes
Operating Temperature (TJ)	150°C	150°C	Yes
Mounting Type	Through Hole	Through Hole	Yes
Package / Case	TO-225AA, TO-126-3	TO-225AA, TO-126-3	Yes
Product Status	Obsolete	Active	Favorable

Engineering Selection Recommendations

The BD678 is the qualified substitute for the MJE700STU based on the following factors:

Electrical Equivalence: All critical electrical parameters match or exceed the MJE700STU specification. The BD678 collector cutoff current of 500 µA is higher than the MJE700STU specification of 100 µA; this represents a less stringent leakage characteristic and does not restrict substitution in applications where the MJE700STU was previously used.

Product Status: The BD678 carries Active product status from STMicroelectronics, ensuring ongoing availability and manufacturing support. This addresses the obsolescence of the MJE700STU and provides long-term procurement stability.

Compliance and Certifications: The BD678 is RoHS3 Compliant and maintains REACH Unaffected status, consistent with the MJE700STU. Both devices carry ECCN EAR99 and HTSUS 8541.29.0095 classifications. Moisture sensitivity level is 1 (Unlimited) for both parts.

Mechanical Compatibility: Both devices employ through-hole mounting with TO-126-3 package designation, enabling direct PCB footprint compatibility without layout modification.

Frequently Asked Questions (FAQ)

Q: Can the BD678 be used as a direct replacement for the MJE700STU in existing designs?

A: Yes. The BD678 meets all electrical specifications of the MJE700STU and shares identical through-hole package geometry. No circuit modifications or PCB layout changes are required for substitution.

Q: What is the significance of the higher collector cutoff current in the BD678?

A: The BD678 specifies a maximum collector cutoff current of 500 µA compared to the MJE700STU at 100 µA. This parameter represents leakage current in the off state. The higher specification in the BD678 is acceptable for applications where the MJE700STU was used, as it does not degrade circuit performance in typical switching and amplification applications.

Q: Are there package compatibility concerns between the MJE700STU and BD678?

A: No. Both devices are specified for TO-126-3 through-hole packages with identical mechanical dimensions and pin configurations. Direct PCB substitution is possible without layout modification.

Q: Why is the BD678 recommended over the MJE700STU?

A: The MJE700STU is classified as obsolete, creating procurement and long-term availability risks. The BD678 is an active product from STMicroelectronics with equivalent electrical performance and superior supply chain status.

Q: Are there compliance or regulatory differences between these parts?

A: No. Both devices carry identical REACH and ECCN classifications (REACH Unaffected, EAR99). The BD678 is RoHS3 Compliant, meeting current regulatory requirements. Moisture sensitivity level is 1 (Unlimited) for both parts.

Q: What thermal characteristics should be considered during substitution?

A: Both the MJE700STU and BD678 are rated for 150°C maximum junction temperature and 40 W maximum power dissipation. Thermal management requirements remain unchanged during substitution.

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