FMMTA14TC Equivalent & Substitute Parts

Part Overview

The FMMTA14TC is an NPN Darlington bipolar junction transistor manufactured by Diodes Incorporated, designed for surface mount applications in the SOT-23-3 package. This device is rated for 40 V collector-emitter breakdown voltage and 300 mA maximum collector current with 330 mW power dissipation capability. The FMMTA14TC is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and ongoing production requirements. Substitute parts must maintain functional compatibility across critical electrical parameters including voltage rating, current capacity, and thermal operating range.

Key Parameters

Parameter	FMMTA14TC	Unit
Transistor Type	NPN - Darlington	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	300	mA
Power - Max	330	mW
DC Current Gain (hFE) (Min) @ Ic, Vce	20000 @ 100mA, 5V	—
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the FMMTA14TC is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN - Darlington configuration
Voltage Rating: Minimum 40 V collector-emitter breakdown voltage
Current Capacity: Minimum 300 mA collector current rating
Package: SOT-23-3 surface mount form factor
Operating Temperature: Support for -55°C to 150°C range
DC Current Gain: Minimum 20000 hFE at specified test conditions

Substitution Logic: Parts are grouped into two categories based on electrical performance:

Category A - Direct Current Equivalents (300 mA rated): Parts maintaining the exact 300 mA collector current specification with 40 V voltage rating. These provide pin-for-pin compatibility with identical electrical performance envelope.

Category B - Enhanced Current Capability (500 mA rated): Parts rated for 500 mA collector current with 40 V voltage rating. These provide superior current handling capacity while maintaining voltage compatibility and are suitable for applications where additional current margin is beneficial.

Secondary Consideration - Reduced Voltage Ratings (30-32 V): Parts with reduced voltage ratings below 40 V are listed for reference but require circuit voltage verification before substitution.

Parameter Comparison

Parameter	FMMTA14TC	MMBT6427-7-F	MMBT6427LT1G	SMMBT6427LT1G	2SD2142KT146	2SD1383KT146B
Manufacturer	Diodes Inc.	Diodes Inc.	onsemi	onsemi	Rohm Semi.	Rohm Semi.
Transistor Type	NPN - Darlington	NPN - Darlington	NPN - Darlington	NPN - Darlington	NPN - Darlington	NPN - Darlington
Voltage - Collector Emitter Breakdown (Max)	40 V	40 V	40 V	40 V	30 V	32 V
Current - Collector (Ic) (Max)	300 mA	500 mA	500 mA	500 mA	300 mA	300 mA
Power - Max	330 mW	300 mW	225 mW	225 mW	200 mW	200 mW
DC Current Gain (hFE) (Min) @ Ic, Vce	20000 @ 100mA, 5V	20000 @ 100mA, 5V	20000 @ 100mA, 5V	20000 @ 100mA, 5V	10000 @ 100mA, 5V	5000 @ 100mA, 5V
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 150°C	Not specified	150°C (Max)	150°C (Max)
Package / Case	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes (Recommended for New Designs):

The MMBT6427-7-F (Diodes Incorporated) and MMBT6427LT1G (onsemi) are the preferred substitutes for the FMMTA14TC. Both devices are active products with full production support, maintain the 40 V voltage rating, provide enhanced 500 mA current capacity, and support the complete -55°C to 150°C operating temperature range. The MMBT6427-7-F carries AEC-Q101 automotive qualification, suitable for applications requiring automotive-grade reliability. The MMBT6427LT1G provides equivalent electrical performance with standard industrial qualification. Both maintain the SOT-23-3 package form factor and achieve the required 20000 hFE minimum gain specification.

Secondary Substitutes (Conditional Use):

The SMMBT6427LT1G (onsemi) provides identical electrical specifications to the MMBT6427LT1G with Tape & Reel packaging. Operating temperature range is not specified for this variant; verification against application requirements is necessary before selection.

The 2SD2142KT146 (Rohm Semiconductor) maintains 300 mA current rating and 40 V voltage compatibility but operates at reduced maximum temperature (150°C maximum only, not -55°C minimum specified). This part is suitable for applications operating within 0°C to 150°C range.

The 2SD1383KT146B (Rohm Semiconductor) provides 300 mA current rating but operates at reduced 32 V voltage rating and exhibits lower DC current gain (5000 hFE minimum). This part is suitable only for applications with voltage requirements of 32 V or lower.

Compliance Status:

All substitute parts maintain ROHS3 compliance, REACH unaffected status, and EAR99 export classification consistent with the original FMMTA14TC.

Frequently Asked Questions (FAQ)

Q: Can the MMBT6427-7-F directly replace the FMMTA14TC in existing designs?

A: Yes. The MMBT6427-7-F maintains the 40 V voltage rating, SOT-23-3 package, and -55°C to 150°C operating temperature range. The enhanced 500 mA current rating provides additional design margin. Pin configuration is identical for NPN Darlington SOT-23-3 devices (Base, Collector, Emitter).

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

A: Both devices provide identical electrical specifications: 40 V rating, 500 mA current capacity, 20000 hFE minimum gain, and SOT-23-3 package. The primary difference is manufacturer (Diodes Incorporated versus onsemi) and packaging format (Cut Tape & Digi-Reel versus standard Cut Tape & Digi-Reel). The MMBT6427-7-F includes AEC-Q101 automotive qualification.

Q: Why is the 2SD1383KT146B listed if it has lower voltage rating?

A: The 2SD1383KT146B is included for reference in applications where circuit voltage requirements are 32 V or lower. This part is not recommended as a direct substitute for the FMMTA14TC in 40 V rated circuits.

Q: Are there package compatibility concerns with SOT-23-3 substitutes?

A: No. All listed substitute parts use the SOT-23-3 (TO-236-3, SC-59) package form factor. PCB footprints and land patterns are identical across all substitutes.

Q: What is the significance of the 20000 hFE specification?

A: The DC current gain (hFE) of 20000 at 100 mA collector current and 5 V collector-emitter voltage is a critical Darlington transistor parameter. This high gain enables efficient base current control and is maintained across the MMBT6427 series and 2SD2142KT146. The 2SD1383KT146B exhibits lower gain (5000 hFE), affecting base drive requirements.

Q: Can SMMBT6427LT1G be used in temperature-critical applications?

A: The SMMBT6427LT1G operating temperature range is not specified in available data. Applications requiring confirmed -55°C to 150°C operation should use MMBT6427-7-F or MMBT6427LT1G instead.

Q: What packaging options are available for the MMBT6427 series?

A: The MMBT6427-7-F is supplied in Cut Tape (CT) & Digi-Reel format. The MMBT6427LT1G is supplied in Cut Tape (CT) & Digi-Reel format. The SMMBT6427LT1G is supplied in Tape & Reel (TR) format for higher-volume automated assembly.

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