FMMT558TC Equivalent & Substitute Parts

Part Overview

The FMMT558TC is a PNP bipolar junction transistor manufactured by Diodes Incorporated, designed for surface mount applications in the SOT-23-3 package. This device operates at 400 V collector-emitter breakdown voltage with a maximum collector current of 150 mA and 500 mW power dissipation. The FMMT558TC is classified as obsolete, necessitating identification of active equivalent and substitute parts for new designs and ongoing production requirements. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts offer comparable performance within defined parameter tolerances suitable for the same application circuits.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	400	V
Current - Collector (Ic) (Max)	150	mA
Power - Max	500	mW
Frequency - Transition	50	MHz
Vce Saturation (Max) @ Ib, Ic	500mV @ 6mA, 50mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 50mA, 10V	—
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the FMMT558TC is determined by strict adherence to the following electrical and mechanical parameters:

Primary Equivalence Criteria:

Transistor Type: PNP
Voltage - Collector Emitter Breakdown (Max): 400 V minimum
Current - Collector (Ic) (Max): 150 mA minimum
Power - Max: 500 mW minimum
Frequency - Transition: 50 MHz minimum
Package / Case: SOT-23-3 compatible
Mounting Type: Surface Mount

Parametric Equivalent Parts maintain all electrical specifications and package requirements identical to the FMMT558TC. These parts are direct replacements with no circuit modifications required.

Manufacturer Recommended Substitute Parts provide comparable performance with variations in one or more electrical parameters. These substitutes remain functionally suitable for applications where the specified parameter variations do not compromise circuit operation. Variations include differences in maximum collector current, power dissipation, saturation voltage, or DC current gain, provided the substitute meets or exceeds the minimum requirements of the application circuit.

Parameter Comparison

Parameter	FMMT558TC	FMMT558TA	FMMT558QTA	MMBTA94-TP	PBHV9040T,215	TSA884CX RFG
Manufacturer	Diodes Inc.	Diodes Inc.	Diodes Inc.	Micro Commercial Co	Nexperia USA Inc.	Taiwan Semiconductor
Product Status	Obsolete	Active	Active	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	400 V	400 V	400 V	400 V	400 V	500 V
Current - Collector (Ic) (Max)	150 mA	150 mA	150 mA	100 mA	250 mA	150 mA
Power - Max	500 mW	500 mW	500 mW	350 mW	300 mW	300 mW
Frequency - Transition	50 MHz	50 MHz	50 MHz	50 MHz	55 MHz	50 MHz
Vce Saturation (Max) @ Ib, Ic	500mV @ 6mA, 50mA	500mV @ 6mA, 50mA	500mV @ 6mA, 50mA	300mV @ 5mA, 50mA	200mV @ 20mA, 100mA	500mV @ 10mA, 50mA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 50mA, 10V	100 @ 50mA, 10V	100 @ 50mA, 10V	80 @ 10mA, 5V	80 @ 100mA, 10V	150 @ 1mA, 10V
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	to 150°C	to 150°C
Package / Case	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23	TO-236AB	SOT-23
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not specified	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	Not specified	1 (Unlimited)	3 (168 Hours)

Engineering Selection Recommendations

Parametric Equivalent Selection:

FMMT558TA and FMMT558QTA are parametric equivalents to the FMMT558TC, maintaining identical electrical specifications and package configuration. Both parts are manufactured by Diodes Incorporated with Active product status. FMMT558TA is available in Cut Tape and Digi-Reel packaging with 95,300 units in stock. FMMT558QTA is available in Tape & Reel packaging with 12,863 units in stock. Both parts carry ROHS3 compliance and MSL 1 rating, matching the original part specifications. These parts are direct replacements requiring no circuit modifications.

Manufacturer Recommended Substitute Selection:

MMBTA94-TP (Micro Commercial Co) operates within the 400 V breakdown voltage specification with reduced maximum collector current of 100 mA and power dissipation of 350 mW. This part is suitable for applications where collector current does not exceed 100 mA. The lower saturation voltage of 300 mV provides improved switching characteristics in certain circuit topologies.

PBHV9040T,215 (Nexperia USA Inc.) provides enhanced current handling capability at 250 mA maximum collector current, exceeding the original specification. Power dissipation is reduced to 300 mW. This part is suitable for applications requiring higher current capacity within the same voltage class. The improved saturation voltage of 200 mV at specified test conditions offers superior switching performance.

TSA884CX RFG (Taiwan Semiconductor Corporation) operates at an elevated breakdown voltage of 500 V, providing additional voltage margin. Maximum collector current and transition frequency match the original specification at 150 mA and 50 MHz. Power dissipation is reduced to 300 mW. This part carries MSL 3 rating requiring controlled moisture exposure during storage and handling. Selection of this part is appropriate for applications requiring enhanced voltage headroom.

All substitute parts maintain ROHS3 compliance and REACH unaffected status. Selection between parametric equivalents and manufacturer recommended substitutes depends on specific application requirements regarding current capacity, power dissipation, and voltage margin.

Frequently Asked Questions (FAQ)

Q: Can FMMT558TA and FMMT558QTA be used interchangeably with FMMT558TC?

A: Yes. FMMT558TA and FMMT558QTA are parametric equivalents with identical electrical specifications and package configuration. The difference between these parts is packaging format: FMMT558TA is supplied in Cut Tape and Digi-Reel format, while FMMT558QTA is supplied in Tape & Reel format. Both are direct replacements for the obsolete FMMT558TC.

Q: What are the key differences between MMBTA94-TP and the original FMMT558TC?

A: MMBTA94-TP has a reduced maximum collector current of 100 mA compared to 150 mA in the FMMT558TC. Power dissipation is also reduced to 350 mW versus 500 mW. The saturation voltage is lower at 300 mV. This part is suitable for applications where collector current remains below 100 mA. The lower saturation voltage may provide improved switching performance in certain circuits.

Q: Is PBHV9040T,215 suitable as a direct replacement?

A: PBHV9040T,215 is a manufacturer recommended substitute with enhanced specifications. Maximum collector current is increased to 250 mA, providing greater current capacity. Power dissipation is reduced to 300 mW. The saturation voltage is significantly lower at 200 mV. This part is suitable for applications requiring higher current handling within the same 400 V voltage class. No circuit modifications are required, but the improved current capacity and lower saturation voltage should be verified as compatible with the application.

Q: What is the advantage of TSA884CX RFG?

A: TSA884CX RFG provides an elevated breakdown voltage of 500 V compared to 400 V in the FMMT558TC. This additional voltage margin is beneficial in applications subject to voltage transients or where design margin is critical. Collector current and transition frequency specifications match the original part. Power dissipation is reduced to 300 mW. This part carries MSL 3 rating, requiring controlled moisture exposure during storage and handling compared to MSL 1 for the original part.

Q: Are all substitute parts ROHS3 compliant?

A: FMMT558TA, FMMT558QTA, PBHV9040T,215, and TSA884CX RFG are all ROHS3 compliant. MMBTA94-TP does not specify RoHS status in the provided data. All parts carry REACH unaffected status.

Q: What is the difference in moisture sensitivity between the substitute parts?

A: FMMT558TA, FMMT558QTA, PBHV9040T,215, and the original FMMT558TC carry MSL 1 rating, indicating unlimited moisture sensitivity level. TSA884CX RFG carries MSL 3 rating, requiring controlled moisture exposure for 168 hours maximum. Parts with MSL 3 require baking prior to reflow soldering if moisture absorption limits are exceeded during storage.

Q: Can MMBTA94-TP be used in high-current applications?

A: MMBTA94-TP has a maximum collector current rating of 100 mA, which is lower than the original FMMT558TC at 150 mA. This part is not suitable for applications requiring collector currents above 100 mA. Verify that application current requirements do not exceed this limit before selection.

Q: What packaging options are available for equivalent parts?

A: FMMT558TA is available in Cut Tape and Digi-Reel packaging. FMMT558QTA is available in Tape & Reel packaging. Both maintain the SOT-23-3 package configuration. MMBTA94-TP is supplied in Bulk packaging. PBHV9040T,215 is supplied in Cut Tape and Digi-Reel packaging. TSA884CX RFG is supplied in Tape & Reel packaging. Selection of packaging format depends on production volume and assembly equipment compatibility.

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