FZT749 Equivalent & Substitute Parts

Part Overview

The FZT749 is a PNP bipolar junction transistor manufactured by onsemi, rated for 25 V collector-emitter breakdown voltage and 3 A maximum collector current in a surface mount SOT-223-4 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The FZT749 operates across a temperature range of -55°C to 150°C and delivers 2 W maximum power dissipation with a 100 MHz transition frequency.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	25	V
Current - Collector (Ic) (Max)	3	A
Vce Saturation (Max) @ Ib, Ic	600 mV @ 300 mA, 3 A	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 1 A, 2 V	—
Power - Max	2	W
Frequency - Transition	100	MHz
Operating Temperature	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-261-4, TO-261AA	—
Current - Collector Cutoff (Max)	100	nA

Substitute Part Grouping Explanation

Substitution of the FZT749 is determined by the following critical parameters:

Mandatory Compatibility Criteria:

Transistor type must be PNP
Collector-emitter breakdown voltage must be greater than or equal to 25 V
Maximum collector current must be greater than or equal to 3 A
Maximum power dissipation must be greater than or equal to 2 W
Operating temperature range must encompass -55°C to 150°C
Mounting type must be surface mount
Package must be compatible with TO-261-4 or TO-261AA footprints

Substitution Categories:

Direct Equivalents maintain identical electrical specifications and package configurations:

FZT749TA (Diodes Incorporated)
FZT749TC (Diodes Incorporated)

Enhanced Performance Substitutes exceed the FZT749 specifications while maintaining backward compatibility:

NSS40300MZ4T1G (onsemi): Higher voltage rating (40 V), improved saturation characteristics
FZT789ATA (Diodes Incorporated): Improved DC current gain and saturation performance
FZT789AQTA (Diodes Incorporated): Higher voltage rating (35 V), enhanced saturation characteristics
STN790A (STMicroelectronics): Higher voltage rating (30 V)
PBSS5350Z,135 (Nexperia USA Inc.): Highest voltage rating (50 V), superior saturation characteristics

Higher Current Capability Substitute:

FZT1149ATA (Diodes Incorporated): 4 A maximum collector current, 2.5 W power rating

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce(br) [V]	Vce Sat [mV]	hFE (Min)	Power [W]	fT [MHz]	Package	Status
FZT749	onsemi	3	25	600 @ 300mA, 3A	100 @ 1A, 2V	2	100	SOT-223-4	Obsolete
FZT749TA	Diodes Incorporated	3	25	600 @ 300mA, 3A	100 @ 1A, 2V	2	160	SOT-223-3	Active
FZT749TC	Diodes Incorporated	3	25	600 @ 300mA, 3A	100 @ 1A, 2V	2	160	SOT-223-3	Active
FZT789ATA	Diodes Incorporated	3	25	500 @ 100mA, 3A	300 @ 10mA, 2V	2	100	SOT-223-3	Active
FZT789AQTA	Diodes Incorporated	3	35	500 @ 100mA, 3A	300 @ 10mA, 2V	1.2	100	SOT-223-3	Active
FZT1149ATA	Diodes Incorporated	4	25	350 @ 140mA, 4A	250 @ 500mA, 2V	2.5	135	SOT-223-3	Active
NSS40300MZ4T1G	onsemi	3	40	400 @ 300mA, 3A	175 @ 1A, 1V	2	160	SOT-223	Active
STN790A	STMicroelectronics	3	30	700 @ 100mA, 3A	100 @ 500mA, 2V	1.6	100	SOT-223	Active
PBSS5350Z,135	Nexperia USA Inc.	3	50	300 @ 200mA, 2A	100 @ 2A, 2V	2	100	SOT-223	Active

Engineering Selection Recommendations

For Direct Replacement with Active Product Status:

FZT749TA and FZT749TC (both Diodes Incorporated) are the primary direct substitutes. Both devices maintain identical electrical specifications to the FZT749 across collector current, breakdown voltage, saturation voltage, and DC current gain. Both are RoHS3 compliant and carry active product status, ensuring long-term availability and supply chain stability. The distinction between FZT749TA and FZT749TC is packaging format: FZT749TA is supplied in Cut Tape with Digi-Reel, while FZT749TC is supplied in Tape & Reel. Selection between these two depends on procurement and assembly requirements.

For Enhanced Voltage Margin Applications:

NSS40300MZ4T1G (onsemi) provides a 40 V collector-emitter breakdown rating compared to the FZT749's 25 V, offering additional voltage headroom in circuits subject to transient overvoltage conditions. This device maintains the 3 A collector current specification and 2 W power rating. The improved saturation characteristics (400 mV versus 600 mV) and higher transition frequency (160 MHz) provide performance enhancements. Active product status and RoHS3 compliance are confirmed.

For Superior Saturation Performance:

FZT789ATA (Diodes Incorporated) delivers improved saturation voltage (500 mV at 100 mA, 3 A versus 600 mV at 300 mA, 3 A) and significantly higher DC current gain (300 @ 10 mA, 2 V versus 100 @ 1 A, 2 V). These characteristics reduce power dissipation in switching applications. Active product status and RoHS3 compliance are confirmed.

For Higher Voltage Applications:

FZT789AQTA (Diodes Incorporated) extends the voltage rating to 35 V while maintaining 3 A collector current. PBSS5350Z,135 (Nexperia USA Inc.) provides the highest voltage rating at 50 V with superior saturation characteristics (300 mV at 200 mA, 2 A). Both devices are active and RoHS3 compliant.

For Higher Current Requirements:

FZT1149ATA (Diodes Incorporated) increases the maximum collector current to 4 A and power dissipation to 2.5 W while maintaining the 25 V voltage rating. This device is suitable for applications requiring higher current handling capacity. Active product status and RoHS3 compliance are confirmed.

Compliance Considerations:

All substitute parts listed carry RoHS3 compliance and REACH Unaffected status, matching the regulatory profile of the FZT749. All devices maintain the -55°C to 150°C operating temperature range. Moisture sensitivity level is MSL 1 (Unlimited) across all parts.

Frequently Asked Questions (FAQ)

Q: Can FZT749TA or FZT749TC be used as direct replacements for FZT749?

A: Yes. FZT749TA and FZT749TC maintain identical electrical specifications for collector current (3 A), breakdown voltage (25 V), saturation voltage (600 mV @ 300 mA, 3 A), and DC current gain (100 @ 1 A, 2 V). Both are active products with RoHS3 compliance. The primary difference is packaging format: FZT749TA is Cut Tape with Digi-Reel, while FZT749TC is Tape & Reel. Both are compatible with TO-261-4 and TO-261AA footprints.

Q: What is the difference between SOT-223-4 and SOT-223-3 packages?

A: The FZT749 uses SOT-223-4 packaging, while most substitute parts use SOT-223-3 packaging. Both are surface mount packages compatible with TO-261-4 and TO-261AA footprints. The primary difference is the number of leads and internal configuration. Verify PCB layout compatibility before substitution.

Q: Can NSS40300MZ4T1G replace FZT749 in all applications?

A: NSS40300MZ4T1G is a suitable substitute for applications where the 25 V voltage rating of FZT749 is adequate. The 40 V rating provides additional voltage margin. The device maintains 3 A collector current and 2 W power dissipation. Improved saturation characteristics (400 mV versus 600 mV) and higher transition frequency (160 MHz versus 100 MHz) may benefit switching performance. Verify circuit requirements before substitution.

Q: What are the advantages of FZT789ATA over FZT749?

A: FZT789ATA provides improved saturation voltage (500 mV at 100 mA, 3 A versus 600 mV at 300 mA, 3 A) and significantly higher DC current gain (300 @ 10 mA, 2 V versus 100 @ 1 A, 2 V). These characteristics reduce power dissipation in switching applications. The device maintains the 25 V voltage rating and 3 A collector current. Transition frequency remains at 100 MHz.

Q: When should FZT1149ATA be selected instead of FZT749?

A: FZT1149ATA is selected when applications require collector current exceeding 3 A. This device is rated for 4 A maximum collector current and 2.5 W power dissipation compared to FZT749's 3 A and 2 W. The 25 V voltage rating matches FZT749. DC current gain is higher (250 @ 500 mA, 2 V), and saturation voltage is lower (350 mV @ 140 mA, 4 A), providing improved efficiency in higher-current switching circuits.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed carry RoHS3 compliance status. The FZT749 is REACH Unaffected, and all substitute parts maintain this regulatory status. Moisture sensitivity level is MSL 1 (Unlimited) across all parts.

Q: What is the operating temperature range for substitute parts?

A: All substitute parts maintain the -55°C to 150°C operating temperature range of the FZT749. This ensures thermal compatibility across the full operating envelope.

Q: Can PBSS5350Z,135 be used in place of FZT749?

A: PBSS5350Z,135 is a suitable substitute for applications where higher voltage margin is required. This device is rated for 50 V collector-emitter breakdown voltage compared to FZT749's 25 V. The 3 A collector current and 2 W power rating match FZT749. Superior saturation characteristics (300 mV at 200 mA, 2 A) provide improved switching performance. Verify circuit requirements before substitution.

Q: What packaging options are available for FZT749 substitutes?

A: Substitute parts are available in multiple packaging formats: Cut Tape (CT) with Digi-Reel, Tape & Reel (TR), and Cut Tape (CT). All devices use SOT-223 or SOT-223-3 packages compatible with TO-261-4 and TO-261AA footprints. Selection depends on procurement and assembly line requirements.

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