MMBT6427LT3G Equivalent & Substitute Parts

Part Overview

The MMBT6427LT3G is an NPN Darlington bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 (TO-236) surface mount package. This component is rated for 40 V collector-emitter breakdown voltage and 500 mA maximum collector current, with a maximum power dissipation of 225 mW. The part is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Direct equivalents and functional alternatives are available from multiple manufacturers with identical or enhanced electrical specifications.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Darlington	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	500	mA
Vce Saturation (Max) @ Ib, Ic	1.5V @ 500µA, 500mA	V
DC Current Gain (hFE) (Min) @ Ic, Vce	20000 @ 100mA, 5V	—
Power - Max	225	mW
Current - Collector Cutoff (Max)	1	µA
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMBT6427LT3G is determined by strict adherence to the following electrical and mechanical parameters:

Critical Matching Parameters:

Transistor Type: NPN - Darlington configuration
Voltage - Collector Emitter Breakdown (Max): 40 V minimum
Current - Collector (Ic) (Max): 500 mA minimum
Vce Saturation: 1.5V @ 500µA, 500mA
DC Current Gain (hFE) (Min): 20000 @ 100mA, 5V minimum
Power - Max: 225 mW minimum
Package / Case: SOT-23-3 (TO-236) or equivalent surface mount package

Substitution Categories:

Direct Equivalents (Identical Electrical Specifications): Parts meeting all critical parameters with identical or superior ratings in the same package family (SOT-23-3).

Functional Alternatives (Similar Electrical Specifications): Parts with reduced voltage or current ratings but maintaining Darlington configuration and surface mount packaging. These are suitable for applications with lower voltage or current requirements.

Package Variants (Different Surface Mount Package): Parts with identical electrical specifications but housed in alternative surface mount packages (SOT-323) requiring PCB layout modification.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce Breakdown (Max) V	hFE (Min) @ 100mA, 5V	Power (Max) mW	Package	Operating Temp °C	RoHS Status
MMBT6427LT3G	onsemi	Obsolete	500	40	20000	225	SOT-23-3	—	—
SMMBT6427LT1G	onsemi	Active	500	40	20000	225	SOT-23-3	—	ROHS3 Compliant
MMBT6427-7-F	Diodes Incorporated	Active	500	40	20000	300	SOT-23-3	-55 ~ 150	ROHS3 Compliant
MMST6427-7-F	Diodes Incorporated	Active	500	40	20000	200	SOT-323	-55 ~ 150	ROHS3 Compliant
2SD2142KT146	Rohm Semiconductor	Active	300	30	10000	200	SOT-23-3	150	ROHS3 Compliant
2SD1383KT146B	Rohm Semiconductor	Active	300	32	5000	200	SOT-23-3	150	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation - Direct Equivalent:

SMMBT6427LT1G (onsemi) is the direct equivalent replacement for the obsolete MMBT6427LT3G. This part maintains identical electrical specifications across all critical parameters: 500 mA collector current, 40 V breakdown voltage, 20000 hFE minimum, and 225 mW power rating. The SMMBT6427LT1G is active in production status and ROHS3 compliant, making it suitable for new designs and production continuity.

Secondary Recommendation - Enhanced Specification:

MMBT6427-7-F (Diodes Incorporated) provides identical electrical performance to the main part with enhanced power dissipation capability (300 mW versus 225 mW). This part is active, ROHS3 compliant, and qualified to AEC-Q101 automotive standards. The extended operating temperature range (-55°C to 150°C) provides additional thermal margin for demanding applications.

Alternative for Space-Constrained Designs:

MMST6427-7-F (Diodes Incorporated) offers identical electrical specifications in a smaller SOT-323 package. This part is suitable for applications requiring reduced PCB footprint. The SOT-323 package requires PCB layout modification and is not a direct pin-compatible replacement.

Functional Alternatives for Reduced-Specification Applications:

2SD2142KT146 and 2SD1383KT146B are functional alternatives suitable only for applications with reduced voltage (30-32 V) or current (300 mA) requirements. These parts are not direct substitutes for the full-specification MMBT6427LT3G but may be used in designs with lower electrical demands.

Frequently Asked Questions (FAQ)

Q: Can SMMBT6427LT1G be used as a direct replacement for MMBT6427LT3G?

A: Yes. SMMBT6427LT1G is a direct equivalent with identical electrical specifications. Both parts are NPN Darlington transistors with 500 mA collector current, 40 V breakdown voltage, and 20000 hFE minimum. The primary difference is product status: SMMBT6427LT1G is active in production, while MMBT6427LT3G is obsolete. SMMBT6427LT1G is ROHS3 compliant and suitable for new designs.

Q: What is the difference between MMBT6427-7-F and SMMBT6427LT1G?

A: Both parts have identical electrical specifications and are pin-compatible in SOT-23-3 packages. MMBT6427-7-F offers higher power dissipation (300 mW versus 225 mW), extended operating temperature range (-55°C to 150°C), and AEC-Q101 automotive qualification. SMMBT6427LT1G is the standard industrial-grade equivalent. Selection depends on application thermal requirements and automotive qualification needs.

Q: Can MMST6427-7-F replace MMBT6427LT3G in existing designs?

A: MMST6427-7-F has identical electrical specifications but uses a different package (SOT-323 versus SOT-23-3). This part is not pin-compatible and requires PCB layout modification. Use MMST6427-7-F only in new designs where the smaller SOT-323 footprint is beneficial.

Q: Are 2SD2142KT146 and 2SD1383KT146B suitable replacements?

A: These parts are functional alternatives only for applications with reduced electrical requirements. Both have lower maximum collector current (300 mA versus 500 mA) and lower breakdown voltage (30-32 V versus 40 V). They are not direct substitutes for the full-specification MMBT6427LT3G. Use these parts only when application specifications permit reduced voltage and current ratings.

Q: What packaging options are available?

A: The MMBT6427LT3G and its direct equivalents use SOT-23-3 (TO-236) surface mount packaging. MMST6427-7-F provides an alternative in SOT-323 (SC-70) packaging with smaller footprint. All substitute parts listed are surface mount devices suitable for automated assembly.

Q: Are all substitute parts ROHS3 compliant?

A: SMMBT6427LT1G, MMBT6427-7-F, MMST6427-7-F, 2SD2142KT146, and 2SD1383KT146B are all ROHS3 compliant. The original MMBT6427LT3G does not specify RoHS status. For applications requiring RoHS compliance, use any of the listed active substitutes.

Q: What is the moisture sensitivity level for these parts?

A: All listed parts have Moisture Sensitivity Level (MSL) 1, indicating unlimited shelf life without moisture control requirements. Standard handling and storage practices are sufficient.

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