FMMT491QTC Equivalent & Substitute Parts

Part Overview

The FMMT491QTC is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for general-purpose switching and amplification applications. This surface mount device operates at 60 V collector-emitter breakdown voltage with a maximum collector current of 1 A and 500 mW power dissipation. The part is classified as Active product status with AEC-Q101 automotive qualification and ROHS3 compliance. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to inventory constraints, manufacturing discontinuation, or design flexibility needs.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	60	V
Current - Collector (Ic) (Max)	1	A
Power - Max	500	mW
Frequency - Transition	150	MHz
Vce Saturation (Max) @ Ib, Ic	250mV @ 100mA, 1A	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 500mA, 5V	—
Current - Collector Cutoff (Max)	100	nA
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the FMMT491QTC are classified into two categories based on electrical and mechanical compatibility:

Parametric Equivalents (Diodes Incorporated FMMT491 Series): Parts FMMT491QTA, FMMT491TA, and FMMT491TC share identical electrical specifications with the main part. These substitutes maintain the same collector-emitter breakdown voltage (60 V), maximum collector current (1 A), saturation voltage (250 mV @ 100mA, 1A), transition frequency (150 MHz), power dissipation (500 mW), DC current gain (100 @ 500mA, 5V), and operating temperature range (-55°C to 150°C). The primary differences are packaging format (Tape & Reel versus Cut Tape & Digi-Reel) and inventory availability. All parts use the SOT-23-3 package and maintain ROHS3 compliance and MSL 1 rating.

Manufacturer Recommended Alternatives (Nexperia PBSS4160 Series): Parts PBSS4160T,215 and PBSS4160TVL are manufacturer-recommended substitutes from Nexperia USA Inc. These parts maintain the same collector-emitter breakdown voltage (60 V), maximum collector current (1 A), and saturation voltage (250 mV @ 100mA, 1A). However, they feature higher transition frequency (220 MHz versus 150 MHz) and lower maximum power dissipation (400 mW versus 500 mW). DC current gain specifications differ: PBSS4160T,215 specifies 200 @ 500mA, 5V, while PBSS4160TVL specifies 250 @ 1mA, 5V. Operating temperature maximum is 150°C. Both use TO-236AB package designation and maintain ROHS3 compliance and MSL 1 rating.

Parameter Comparison

Parameter	FMMT491QTC	FMMT491QTA	FMMT491TA	FMMT491TC	PBSS4160T,215	PBSS4160TVL
Manufacturer	Diodes Inc.	Diodes Inc.	Diodes Inc.	Diodes Inc.	Nexperia USA Inc.	Nexperia USA Inc.
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	60 V	60 V	60 V	60 V	60 V	60 V
Current - Collector (Ic) (Max)	1 A	1 A	1 A	1 A	1 A	1 A
Power - Max	500 mW	500 mW	500 mW	500 mW	400 mW	400 mW
Frequency - Transition	150 MHz	150 MHz	150 MHz	150 MHz	220 MHz	220 MHz
Vce Saturation (Max) @ Ib, Ic	250mV @ 100mA, 1A	250mV @ 100mA, 1A	250mV @ 100mA, 1A	250mV @ 100mA, 1A	250mV @ 100mA, 1A	250mV @ 100mA, 1A
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 500mA, 5V	100 @ 500mA, 5V	100 @ 500mA, 5V	100 @ 500mA, 5V	200 @ 500mA, 5V	250 @ 1mA, 5V
Current - Collector Cutoff (Max)	100 nA	100 nA	100 nA	100 nA	100 nA	100 nA
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-23-3	TO-236AB	TO-236AB
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Packaging Format	Tape & Reel (TR)	Tape & Reel (TR)	Cut Tape & Digi-Reel	Tape & Reel (TR)	Tape & Reel (TR)	Tape & Reel (TR)

Engineering Selection Recommendations

Diodes Incorporated FMMT491 Series (FMMT491QTA, FMMT491TA, FMMT491TC): These parts are direct parametric equivalents to the FMMT491QTC and are the primary substitution choice. All three maintain identical electrical specifications and are Active product status with ROHS3 compliance and AEC-Q101 automotive qualification. Selection among these three is determined by packaging format requirements: FMMT491QTC and FMMT491QTA are supplied in Tape & Reel format, while FMMT491TA is supplied in Cut Tape & Digi-Reel format. Inventory availability differs significantly, with FMMT491TA offering the highest stock level (102,610 pcs).

Nexperia PBSS4160 Series (PBSS4160T,215, PBSS4160TVL): These manufacturer-recommended alternatives are suitable when higher transition frequency (220 MHz) is beneficial or when Nexperia sourcing is preferred. Both parts maintain the critical electrical parameters: 60 V breakdown voltage, 1 A maximum collector current, and 250 mV saturation voltage. The reduced power dissipation rating (400 mW versus 500 mW) requires thermal design verification in applications approaching the original 500 mW specification. DC current gain is higher in both Nexperia parts, which may affect biasing calculations in current-dependent circuits. Both parts are Active product status with ROHS3 compliance and MSL 1 rating. PBSS4160T,215 offers higher inventory (5,700 pcs) compared to PBSS4160TVL (1,038 pcs).

Frequently Asked Questions (FAQ)

Q: Can FMMT491QTA, FMMT491TA, and FMMT491TC be used interchangeably with FMMT491QTC?

A: Yes. These three parts are parametric equivalents with identical electrical specifications. The differences are packaging format (Tape & Reel versus Cut Tape & Digi-Reel) and inventory levels. PCB layout and assembly process requirements determine which packaging format is appropriate.

Q: What are the key differences between the Diodes FMMT491 series and the Nexperia PBSS4160 series?

A: The primary differences are transition frequency (150 MHz for FMMT491 versus 220 MHz for PBSS4160) and maximum power dissipation (500 mW for FMMT491 versus 400 mW for PBSS4160). DC current gain specifications also differ. Both series maintain the same 60 V breakdown voltage, 1 A maximum collector current, and 250 mV saturation voltage.

Q: Are the SOT-23-3 and TO-236AB packages physically compatible?

A: SOT-23-3 and TO-236AB are equivalent package designations for the same physical form factor. Both are three-lead surface mount packages with identical pin spacing and dimensions. PCB footprints designed for one package accommodate the other.

Q: Can I use PBSS4160T,215 or PBSS4160TVL in a design specified for 500 mW power dissipation?

A: The PBSS4160 series has a maximum power dissipation rating of 400 mW. Applications requiring sustained operation at 500 mW must use the FMMT491 series. Applications operating below 400 mW can use either series.

Q: What is the significance of the different DC current gain specifications?

A: DC current gain (hFE) affects base current requirements for saturation. FMMT491QTC specifies 100 @ 500mA, 5V. PBSS4160T,215 specifies 200 @ 500mA, 5V, and PBSS4160TVL specifies 250 @ 1mA, 5V. Higher gain reduces base current requirements. Circuits with fixed base current biasing may require adjustment when switching between these parts.

Q: Are all substitute parts AEC-Q101 qualified?

A: The Diodes FMMT491 series (FMMT491QTC, FMMT491QTA, FMMT491TA, FMMT491TC) carries AEC-Q101 automotive qualification. The Nexperia PBSS4160 series qualification status is not specified in the provided parameters.

Q: What is the inventory status of each substitute part?

A: FMMT491TA has the highest inventory (102,610 pcs), followed by FMMT491TC (25,400 pcs), FMMT491QTA (20,200 pcs), PBSS4160T,215 (5,700 pcs), FMMT491QTC (765 pcs), and PBSS4160TVL (1,038 pcs).

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