MMBT6427LT3 Equivalent & Substitute Parts

Part Overview

The MMBT6427LT3 is an NPN Darlington bipolar junction transistor manufactured by onsemi, designed for surface mount applications in the SOT-23-3 package. This component operates at a maximum collector current of 500 mA with a 40 V collector-emitter breakdown voltage and 225 mW power dissipation capability. The part is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements.

Key Parameters

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

Substitute Part Grouping Explanation

Substitution of the MMBT6427LT3 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN - Darlington configuration
Maximum Collector Current (Ic): 500 mA or greater
Collector-Emitter Breakdown Voltage (Vce): 40 V or greater
Vce Saturation: 1.5V @ 500µA, 500mA or equivalent
DC Current Gain (hFE): 20000 @ 100mA, 5V or greater
Power Dissipation: 225 mW or greater
Package: SOT-23-3 (TO-236-3, SC-59) surface mount

Substitution Categories:

Direct Equivalents maintain all electrical specifications and package requirements, differing only in product status or compliance certifications. These parts are pin-compatible and functionally identical.

Similar Substitutes share the NPN Darlington topology and SOT-23-3 package but operate within reduced electrical parameters. These parts are suitable for applications where the lower current, voltage, or power ratings are acceptable within the circuit design constraints.

Parameter Comparison

Parameter	MMBT6427LT3 (Main)	MMBT6427LT1G (Direct)	MMBT6427-7-F (Direct)	2SD1383KT146B (Similar)	2SD2142KT146 (Similar)
Manufacturer	onsemi	onsemi	Diodes Incorporated	Rohm Semiconductor	Rohm Semiconductor
Transistor Type	NPN - Darlington	NPN - Darlington	NPN - Darlington	NPN - Darlington	NPN - Darlington
Current - Collector (Ic) (Max)	500 mA	500 mA	500 mA	300 mA	300 mA
Voltage - Collector Emitter Breakdown (Max)	40 V	40 V	40 V	32 V	30 V
Vce Saturation (Max) @ Ib, Ic	1.5V @ 500µA, 500mA	1.5V @ 500µA, 500mA	1.5V @ 500µA, 500mA	1.5V @ 400µA, 200mA	1.5V @ 100µA, 100mA
Current - Collector Cutoff (Max)	1 µA	1 µA	1 µA	1 µA (ICBO)	100 nA (ICBO)
DC Current Gain (hFE) (Min) @ Ic, Vce	20000 @ 100mA, 5V	20000 @ 100mA, 5V	20000 @ 100mA, 5V	5000 @ 100mA, 5V	10000 @ 100mA, 5V
Power - Max	225 mW	225 mW	300 mW	200 mW	200 mW
Frequency - Transition	—	—	—	250 MHz	200 MHz
Operating Temperature	—	-55°C ~ 150°C (TJ)	-55°C ~ 150°C (TJ)	150°C (TJ)	150°C (TJ)
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Direct Equivalent Selection:

MMBT6427LT1G is the primary direct equivalent to the MMBT6427LT3. This onsemi component maintains identical electrical specifications including 500 mA maximum collector current, 40 V breakdown voltage, 20000 hFE minimum gain, and 225 mW power dissipation. The part is active in production status and ROHS3 compliant, addressing the obsolescence of the original component. Operating temperature range of -55°C to 150°C (TJ) is specified.

MMBT6427-7-F, manufactured by Diodes Incorporated, provides an alternative direct equivalent with identical electrical performance. This part features 300 mW maximum power dissipation, exceeding the original specification. The component carries AEC-Q101 automotive qualification and ROHS3 compliance. Operating temperature range matches the onsemi equivalent at -55°C to 150°C (TJ).

Similar Substitute Selection:

2SD1383KT146B and 2SD2142KT146, both manufactured by Rohm Semiconductor, are similar substitutes suitable for applications where reduced electrical parameters are acceptable. These parts operate at 300 mA maximum collector current and reduced breakdown voltages (32 V and 30 V respectively), compared to the 500 mA and 40 V specifications of the main part. Both components are ROHS3 compliant and active in production. Selection of similar substitutes requires circuit-level analysis to confirm that the reduced current and voltage ratings do not compromise application performance.

Frequently Asked Questions (FAQ)

Q: Can MMBT6427LT1G be used as a direct replacement for MMBT6427LT3?

A: Yes. MMBT6427LT1G is a direct equivalent with identical electrical specifications and SOT-23-3 package. The primary difference is product status: MMBT6427LT1G is active and ROHS3 compliant, while MMBT6427LT3 is obsolete and RoHS non-compliant. Pin configuration and electrical performance are identical.

Q: What is the difference between MMBT6427-7-F and MMBT6427LT1G?

A: Both are direct equivalents with identical core electrical specifications. MMBT6427-7-F is manufactured by Diodes Incorporated and features 300 mW maximum power dissipation compared to 225 mW for MMBT6427LT1G. MMBT6427-7-F carries AEC-Q101 automotive qualification. Both operate at -55°C to 150°C (TJ) and are ROHS3 compliant.

Q: Can 2SD1383KT146B or 2SD2142KT146 replace MMBT6427LT3 in all applications?

A: These are similar substitutes, not direct equivalents. They operate at reduced maximum collector current (300 mA versus 500 mA) and lower breakdown voltages (32 V and 30 V versus 40 V). Substitution is valid only when circuit design margins accommodate these reduced ratings. Applications requiring the full 500 mA current or 40 V voltage capability must use direct equivalents.

Q: Are all substitute parts available in the same SOT-23-3 package?

A: Yes. All listed substitute parts use the SOT-23-3 package (also designated TO-236-3 or SC-59). Pin configuration is identical across all parts, enabling direct PCB footprint compatibility.

Q: What compliance certifications apply to the substitute parts?

A: MMBT6427LT1G and MMBT6427-7-F are ROHS3 compliant. MMBT6427-7-F additionally carries AEC-Q101 automotive qualification. All substitute parts are REACH unaffected and classified under ECCN EAR99. The original MMBT6427LT3 is RoHS non-compliant.

Q: Does operating temperature range affect substitution decisions?

A: MMBT6427LT1G and MMBT6427-7-F specify -55°C to 150°C (TJ) operating range. The original MMBT6427LT3 does not specify operating temperature. For applications requiring defined temperature performance, the direct equivalents provide explicit thermal specifications. Similar substitutes 2SD1383KT146B and 2SD2142KT146 specify 150°C (TJ) maximum.

Q: What is the significance of DC Current Gain (hFE) differences between parts?

A: MMBT6427LT3, MMBT6427LT1G, and MMBT6427-7-F all specify 20000 hFE minimum at 100 mA and 5 V. Similar substitutes specify lower hFE: 2SD1383KT146B at 5000 and 2SD2142KT146 at 10000. Higher hFE enables greater current amplification with lower base drive requirements. Applications sensitive to base current requirements must account for hFE differences when using similar substitutes.

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