MMSTA42-7 NPN Bipolar Transistor Equivalent & Substitute Parts

Part Overview

The MMSTA42-7 is a surface mount NPN bipolar junction transistor manufactured by Diodes Incorporated, housed in a SOT-323 package. This component is rated for 300 V collector-emitter breakdown voltage with a maximum collector current of 200 mA and 200 mW power dissipation. The part is currently discontinued at DiGi Electronics, necessitating identification of equivalent and substitute components for ongoing design requirements and production needs.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	200	mW
Frequency - Transition	50	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	40 @ 30mA, 10V	—
Vce Saturation (Max) @ Ib, Ic	500mV @ 2mA, 20mA	—
Operating Temperature Range	-55 to 150	°C
Package / Case	SC-70, SOT-323	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the MMSTA42-7 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor type (NPN)
Voltage rating (300 V minimum collector-emitter breakdown)
Current rating (200 mA or greater for direct substitution)
Power dissipation (200 mW or greater)
Frequency response (50 MHz or greater)
DC current gain (hFE minimum 40 @ specified conditions)
Saturation voltage characteristics
Surface mount package compatibility (SOT-323 or equivalent footprint)

Substitution Categories:

Direct Manufacturer Equivalent: Parts with identical electrical specifications and the same base product number (MMSTA42) but different packaging or compliance status.

Manufacturer Recommended Equivalent: Parts from alternative manufacturers meeting or exceeding all critical electrical parameters with the same package footprint, offering improved availability or compliance status.

Parametric Equivalent: Parts with identical or superior electrical specifications and compatible package types, enabling functional replacement in circuit applications.

Parameter Comparison

Parameter	MMSTA42-7	MMSTA42-7-F	BF820W,115	MMBTA42-TP	NSVMSD42WT1G	PMSTA42,115	MMSTA42-TP
Manufacturer	Diodes Inc.	Diodes Inc.	Nexperia USA	Micro Commercial	onsemi	Nexperia USA	Micro Commercial
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Ic (Max) [mA]	200	200	50	500	150	100	200
Vce Breakdown (Max) [V]	300	300	300	300	300	300	300
Power (Max) [mW]	200	200	200	225	450	200	200
Frequency - Transition [MHz]	50	50	60	50	—	50	50
hFE (Min) @ Ic, Vce	40 @ 30mA, 10V	40 @ 30mA, 10V	50 @ 25mA, 20V	40 @ 30mA, 10V	40 @ 30mA, 10V	40 @ 30mA, 10V	40 @ 30mA, 10V
Vce Saturation (Max) @ Ib, Ic	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA	600mV @ 5mA, 30mA	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA	500mV @ 2mA, 20mA
Operating Temperature [°C]	-55 to 150	-55 to 150	to 150	-55 to 150	-55 to 150	to 150	-55 to 150
Package	SOT-323	SOT-323	SOT-323	SOT-23	SOT-323	SOT-323	SOT-323
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Discontinued	Active	Active	Active	Active	Active	Active
Automotive Grade	—	—	Yes (AEC-Q101)	—	—	Yes (AEC-Q101)	—

Engineering Selection Recommendations

Primary Recommendation: MMSTA42-7-F

The MMSTA42-7-F is the direct equivalent of the MMSTA42-7, manufactured by Diodes Incorporated with identical electrical specifications. This part differs only in packaging format (Tape & Reel) and compliance status (ROHS3 Compliant). The MMSTA42-7-F maintains full parametric compatibility and is the preferred replacement for direct substitution. Product status is Active with 9,670 units in stock.

Secondary Recommendation: MMSTA42-TP

The MMSTA42-TP, manufactured by Micro Commercial Co, is a parametric equivalent offering identical electrical specifications to the MMSTA42-7. This part maintains the same 200 mA collector current, 300 V breakdown voltage, 200 mW power rating, and SOT-323 package. ROHS3 compliance and Active product status make this a viable alternative with 8,626 units in stock.

Application-Specific Recommendations:

For automotive applications requiring AEC-Q101 qualification, the PMSTA42,115 (Nexperia USA Inc.) or BF820W,115 (Nexperia USA Inc.) are suitable alternatives. Both parts carry automotive-grade certification. The PMSTA42,115 maintains the full 200 mA current rating, while the BF820W,115 is rated for 50 mA maximum collector current and is appropriate only for lower-current applications.

For applications requiring higher power dissipation, the NSVMSD42WT1G (onsemi) provides 450 mW maximum power in a compatible SOT-323 package with 150 mA collector current rating.

For applications tolerating higher collector current, the MMBTA42-TP (Micro Commercial Co) offers 500 mA maximum collector current in a SOT-23 package. This part requires PCB layout modification due to different package footprint.

All recommended substitutes maintain the 300 V breakdown voltage, 50 MHz transition frequency, and compatible saturation voltage characteristics of the original part.

Frequently Asked Questions (FAQ)

Q: Can the MMSTA42-7-F be used as a direct replacement for MMSTA42-7?

A: Yes. The MMSTA42-7-F is manufactured by the same company (Diodes Incorporated) with identical electrical specifications, operating temperature range, and package footprint (SOT-323). The only differences are packaging format (Tape & Reel) and RoHS compliance status (ROHS3 Compliant versus non-compliant). No circuit modifications are required.

Q: What is the difference between MMSTA42-TP and MMSTA42-7?

A: The MMSTA42-TP is manufactured by Micro Commercial Co rather than Diodes Incorporated, but maintains identical electrical specifications including 200 mA collector current, 300 V breakdown voltage, 200 mW power dissipation, and SOT-323 package. Both parts are functionally equivalent for circuit applications.

Q: Can BF820W,115 replace MMSTA42-7 in all applications?

A: The BF820W,115 is suitable only for applications where the collector current does not exceed 50 mA. This part is rated for 50 mA maximum collector current compared to the MMSTA42-7's 200 mA rating. The BF820W,115 offers advantages including automotive-grade qualification (AEC-Q101) and higher transition frequency (60 MHz). Verify circuit current requirements before substitution.

Q: Why is MMBTA42-TP listed as a substitute if it uses a different package?

A: The MMBTA42-TP uses a SOT-23 package instead of SOT-323, requiring PCB layout modification. However, it is included as a parametric equivalent because it offers superior electrical specifications: 500 mA collector current (2.5× the original), 225 mW power dissipation, and identical saturation voltage characteristics. This part is suitable for designs where package footprint can be accommodated.

Q: Are all substitute parts RoHS compliant?

A: All substitute parts listed are ROHS3 Compliant. The original MMSTA42-7 is RoHS non-compliant. If RoHS compliance is a design requirement, any of the listed substitutes satisfy this criterion.

Q: What is the significance of AEC-Q101 qualification?

A: AEC-Q101 is an automotive industry qualification standard. The PMSTA42,115 and BF820W,115 carry this certification, making them suitable for automotive applications requiring qualified components. Non-automotive applications do not require this qualification.

Q: Can NSVMSD42WT1G be used in high-current applications?

A: The NSVMSD42WT1G is rated for 150 mA maximum collector current, which is lower than the MMSTA42-7's 200 mA rating. This part is suitable for applications requiring collector currents up to 150 mA. Its primary advantage is higher power dissipation capability (450 mW versus 200 mW), making it suitable for applications with higher power requirements at lower current levels.

Q: What is the operating temperature range for all substitute parts?

A: Most substitute parts operate from -55°C to 150°C, matching the MMSTA42-7. The PMSTA42,115 and BF820W,115 specify operation to 150°C without a lower temperature limit in the provided data. Verify specific temperature requirements for your application.

Q: Are there any differences in saturation voltage between substitutes?

A: The BF820W,115 specifies 600 mV saturation voltage at 5 mA base current and 30 mA collector current, compared to 500 mV for the MMSTA42-7 at 2 mA base current and 20 mA collector current. All other substitutes maintain the 500 mV saturation voltage specification. This difference may affect switching speed in saturation-mode applications.

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