MJD340 NPN Bipolar Transistor Equivalent & Substitute Parts

Part Overview

The MJD340 is an NPN bipolar junction transistor manufactured by onsemi, rated for 300 V collector-emitter breakdown voltage and 500 mA maximum collector current in a surface mount DPAK package. The original MJD340 part is classified as obsolete, with 9,094 units in stock. Due to its obsolete status, equivalent and substitute parts are necessary for ongoing design support, production continuity, and component sourcing flexibility. Substitute parts maintain electrical compatibility within specified parameter ranges while offering active product status and improved compliance certifications.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	500	mA
Power - Max	15	W
DC Current Gain (hFE) (Min) @ Ic, Vce	30 @ 50mA, 10V	—
Current - Collector Cutoff (Max)	100	µA
Operating Temperature Range	-65 to 150	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	TO-252-3, DPAK (2 Leads + Tab), SC-63	—

Substitute Part Grouping Explanation

Substitute parts for the MJD340 are categorized based on electrical parameter compatibility and package compatibility. The primary substitution criteria are:

Direct Electrical Equivalents: Parts maintaining identical or superior ratings for collector-emitter breakdown voltage (300 V minimum), collector current (500 mA minimum), power dissipation (15 W minimum), and DC current gain (hFE ≥ 30 @ specified conditions). These parts are pin-compatible in the TO-252-3 DPAK package.

Higher-Rated Substitutes: Parts exceeding the MJD340 specifications in voltage, current, or power ratings. These provide design margin and are suitable for applications where the original specifications are met or exceeded. Higher ratings do not preclude substitution when circuit design permits.

Package Compatibility: All substitute parts use the TO-252-3 DPAK package or equivalent surface mount configuration, ensuring mechanical and thermal compatibility.

Compliance and Status: Active product status and RoHS3 compliance are prioritized for long-term availability and regulatory adherence.

Parameter Comparison

Part Number	Manufacturer	Vce Breakdown (V)	Ic Max (mA)	Power Max (W)	hFE Min @ Ic, Vce	Icbo Max (µA)	Operating Temp (°C)	Product Status	RoHS Status
MJD340	onsemi	300	500	15	30 @ 50mA, 10V	100	-65 to 150	Obsolete	Non-compliant
MJD340G	onsemi	300	500	15	30 @ 50mA, 10V	100	-65 to 150	Active	ROHS3 Compliant
MJD340T4	STMicroelectronics	300	500	15	30 @ 50mA, 10V	100	-65 to 150	Active	ROHS3 Compliant
MJD340-13	Diodes Incorporated	300	500	15	30 @ 50mA, 10V	100	-55 to 150	Active	ROHS3 Compliant
FJD5553TM	onsemi	400	3000	1.25	30 @ 400mA, 3V	—	-65 to 150	Active	ROHS3 Compliant
FJD5555TM	onsemi	400	5000	1.34	20 @ 800mA, 3V	—	-65 to 150	Active	ROHS3 Compliant
KSC5402DTF	onsemi	525	2000	30	6 @ 1A, 1V	250	-65 to 150	Last Time Buy	ROHS3 Compliant
KSC5502DTM	onsemi	600	2000	50	4 @ 1A, 1V	100	-65 to 150	Active	ROHS3 Compliant
BULD741T4	STMicroelectronics	400	2500	30	25 @ 450mA, 3V	250	-65 to 150	Active	ROHS3 Compliant
BULD742CT4	STMicroelectronics	400	4000	45	25 @ 800mA, 3V	250	-65 to 150	Active	ROHS3 Compliant
ZXT1053AKTC	Diodes Incorporated	75	5000	4	300 @ 1A, 2V	10	-55 to 150	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (Pin-Compatible, Electrically Identical):

MJD340G, MJD340T4, and MJD340-13 are direct replacements for the obsolete MJD340. All three parts maintain identical electrical specifications: 300 V collector-emitter breakdown voltage, 500 mA maximum collector current, 15 W power dissipation, and 30 hFE minimum at 50 mA, 10 V. All three are active products with RoHS3 compliance, ensuring long-term availability and regulatory adherence. MJD340G is manufactured by onsemi (original manufacturer), MJD340T4 by STMicroelectronics, and MJD340-13 by Diodes Incorporated. Selection among these three depends on supplier availability and procurement preference.

Higher-Rated Substitutes (Electrical Superset):

BULD741T4 and BULD742CT4 (STMicroelectronics) provide higher current ratings (2.5 A and 4 A respectively) and higher power dissipation (30 W and 45 W) while maintaining 400 V collector-emitter breakdown voltage. These parts are suitable for applications where the MJD340 specifications are met and additional design margin is acceptable. Both are active products with RoHS3 compliance.

KSC5402DTF (onsemi) and KSC5502DTM (onsemi) offer significantly higher voltage ratings (525 V and 600 V respectively) with higher power dissipation (30 W and 50 W). These parts are suitable for high-voltage applications where the MJD340 voltage rating is insufficient. KSC5502DTM is active; KSC5402DTF is Last Time Buy status.

FJD5553TM and FJD5555TM (onsemi) provide higher current ratings (3 A and 5 A) and higher voltage ratings (400 V) but lower power dissipation (1.25 W and 1.34 W). These parts are suitable for high-current, lower-power applications.

Not Recommended for Direct Substitution:

ZXT1053AKTC (Diodes Incorporated) has a collector-emitter breakdown voltage of only 75 V, which is significantly below the MJD340 specification of 300 V. This part is not suitable for applications requiring the MJD340 voltage rating.

Frequently Asked Questions (FAQ)

Q: Can MJD340G be used as a direct replacement for the obsolete MJD340?

A: Yes. MJD340G is manufactured by onsemi and maintains identical electrical specifications: 300 V Vce breakdown, 500 mA Ic maximum, 15 W power dissipation, and 30 hFE minimum. MJD340G is an active product with RoHS3 compliance, making it the preferred direct replacement.

Q: What is the difference between MJD340G, MJD340T4, and MJD340-13?

A: All three parts are electrically identical to the original MJD340 with identical ratings for voltage, current, power, and gain. The differences are manufacturer (onsemi, STMicroelectronics, and Diodes Incorporated respectively) and packaging format. Selection depends on supplier availability and procurement requirements.

Q: Can BULD741T4 or BULD742CT4 be used instead of MJD340?

A: Yes, with design verification. BULD741T4 and BULD742CT4 exceed MJD340 specifications in current (2.5 A and 4 A versus 500 mA) and power (30 W and 45 W versus 15 W) while maintaining 400 V Vce breakdown voltage. These parts are suitable when circuit design permits higher current and power ratings. Both are active products with RoHS3 compliance.

Q: Are KSC5402DTF and KSC5502DTM suitable replacements for MJD340?

A: KSC5402DTF and KSC5502DTM are suitable for applications requiring higher voltage ratings (525 V and 600 V respectively) than the MJD340 (300 V). Both parts exceed MJD340 power dissipation specifications (30 W and 50 W versus 15 W). KSC5502DTM is active; KSC5402DTF is Last Time Buy status. Use these parts only when higher voltage capability is required.

Q: Why is ZXT1053AKTC not recommended as a substitute?

A: ZXT1053AKTC has a collector-emitter breakdown voltage of 75 V, which is significantly below the MJD340 specification of 300 V. This part cannot safely operate in circuits designed for 300 V operation and is not a suitable substitute.

Q: Are all substitute parts available in the same DPAK package?

A: Yes. All substitute parts listed use the TO-252-3 DPAK package or equivalent surface mount configuration, ensuring mechanical and thermal compatibility with the original MJD340 footprint.

Q: What is the significance of RoHS3 compliance for substitute parts?

A: RoHS3 compliance indicates adherence to current regulatory requirements for hazardous substance restrictions. All recommended substitute parts carry RoHS3 compliance, ensuring regulatory acceptance and long-term availability. The original MJD340 is RoHS non-compliant, making compliant substitutes necessary for new designs and ongoing production.

Q: Can I use FJD5553TM or FJD5555TM as replacements for MJD340?

A: FJD5553TM and FJD5555TM are suitable only for applications where higher current ratings (3 A and 5 A) and higher voltage ratings (400 V) are acceptable. However, these parts have significantly lower power dissipation (1.25 W and 1.34 W versus 15 W), making them unsuitable for high-power applications. Use these parts only when circuit design permits lower power dissipation.

Q: What is the operating temperature range difference between MJD340 and MJD340-13?

A: The original MJD340 operates from -65°C to 150°C. MJD340-13 operates from -55°C to 150°C, providing a slightly narrower low-temperature range. For applications requiring operation below -55°C, MJD340G or MJD340T4 are preferred.

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