FMMT449 Equivalent & Substitute Parts

Part Overview

The FMMT449 is an NPN bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This device is rated for 30 V collector-emitter breakdown voltage, 1 A maximum collector current, and 500 mW power dissipation. The FMMT449 is classified as obsolete, necessitating identification of active substitute components for new designs and ongoing production requirements. Equivalent parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	30	V
Current - Collector (Ic) (Max)	1	A
Power - Max	500	mW
Frequency - Transition	150	MHz
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

Substitution of the FMMT449 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN configuration
Voltage - Collector Emitter Breakdown (Max): Minimum 30 V
Current - Collector (Ic) (Max): Minimum 1 A
Power - Max: Minimum 500 mW
Package / Case: SOT-23-3 (TO-236-3, SC-59)
Mounting Type: Surface Mount
Operating Temperature Range: -55°C to 150°C (TJ)

The substitute parts identified fall into two distinct categories based on current-handling capability:

Category A: Lower Current Devices (100 mA Maximum) Parts BC848ALT1G, BC848BLT1G, BC848BLT3G, BC848CLT1G, BC848CLT3G, BC849BLT1G, and BC849CLT1G operate at reduced maximum collector current (100 mA) compared to the FMMT449 (1 A). These devices are suitable only for applications where collector current does not exceed 100 mA.

Category B: Higher Current Devices (800 mA Maximum) Part BCW65ALT1G operates at 800 mA maximum collector current, approaching but not fully matching the FMMT449 specification of 1 A. This device is suitable for applications requiring current levels between 100 mA and 800 mA.

Category C: Voltage-Rated Devices (32 V Breakdown) Parts BCW32LT1G and BCW33LT1G feature 32 V collector-emitter breakdown voltage, exceeding the FMMT449 specification of 30 V. These devices are electrically compatible for applications rated at 30 V or lower.

All substitute parts maintain SOT-23-3 package compatibility, surface mount configuration, -55°C to 150°C operating temperature range, ROHS3 compliance, and MSL 1 rating.

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vce Breakdown (Max)	Power (Max)	Frequency - Transition	Package	Product Status
FMMT449	onsemi	1 A	30 V	500 mW	150 MHz	SOT-23-3	Obsolete
BC848ALT1G	onsemi	100 mA	30 V	300 mW	100 MHz	SOT-23-3	Active
BC848BLT1G	onsemi	100 mA	30 V	300 mW	100 MHz	SOT-23-3	Active
BC848BLT3G	onsemi	100 mA	30 V	300 mW	100 MHz	SOT-23-3	Active
BC848CLT1G	onsemi	100 mA	30 V	300 mW	100 MHz	SOT-23-3	Active
BC848CLT3G	onsemi	100 mA	30 V	225 mW	100 MHz	100 MHz	Active
BC849BLT1G	onsemi	100 mA	30 V	300 mW	100 MHz	SOT-23-3	Active
BC849CLT1G	onsemi	100 mA	30 V	300 mW	100 MHz	SOT-23-3	Active
BCW32LT1G	onsemi	100 mA	32 V	225 mW	—	SOT-23-3	Active
BCW33LT1G	onsemi	100 mA	32 V	300 mW	—	SOT-23-3	Active
BCW65ALT1G	onsemi	800 mA	32 V	225 mW	100 MHz	SOT-23-3	Active

Engineering Selection Recommendations

For Direct Replacement (1 A Current Capability): No active substitute part maintains the full 1 A collector current specification of the FMMT449 within the SOT-23-3 package. BCW65ALT1G provides the highest current capability at 800 mA but does not achieve the original 1 A rating.

For Applications ≤ 100 mA: BC848ALT1G, BC848BLT1G, BC848BLT3G, BC848CLT1G, BC848CLT3G, BC849BLT1G, and BC849CLT1G are electrically and mechanically compatible. All devices are active products with ROHS3 compliance and MSL 1 rating. Selection among these parts depends on packaging format (Cut Tape vs. Tape & Reel) and DC current gain requirements.

For Applications 100 mA to 800 mA: BCW65ALT1G is the only substitute providing current capability above 100 mA. This device features 32 V collector-emitter breakdown voltage (exceeding the 30 V FMMT449 specification), 800 mA maximum collector current, and active product status with full compliance certifications.

For Voltage-Margin Applications: BCW32LT1G and BCW33LT1G provide 32 V collector-emitter breakdown voltage, offering additional voltage margin over the FMMT449 specification. These devices are limited to 100 mA collector current and are suitable for low-current applications requiring enhanced voltage rating.

All recommended substitutes maintain surface mount SOT-23-3 package compatibility, -55°C to 150°C operating temperature range, ROHS3 compliance, and MSL 1 moisture sensitivity rating.

Frequently Asked Questions (FAQ)

Q: Can BC848 series transistors directly replace the FMMT449 in all applications?

A: No. BC848 series devices are rated for maximum 100 mA collector current, while the FMMT449 is rated for 1 A. Direct replacement is limited to applications where collector current does not exceed 100 mA. Applications requiring the full 1 A capability require alternative solutions outside the SOT-23-3 package family.

Q: What is the difference between BC848ALT1G, BC848BLT1G, and BC848CLT1G?

A: These devices differ in DC current gain (hFE) specification. BC848ALT1G specifies minimum hFE of 110 at 2 mA and 5 V. BC848BLT1G and BC849BLT1G specify minimum hFE of 200. BC848CLT1G and BC849CLT1G specify minimum hFE of 420. All three maintain identical voltage, current, and power ratings.

Q: Are packaging format differences (Cut Tape vs. Tape & Reel) electrically significant?

A: No. Packaging format differences (CT & Digi-Reel versus Tape & Reel) affect only handling and supply logistics. Electrical and thermal characteristics remain identical. Selection depends on manufacturing process requirements and inventory management.

Q: Why do BCW32LT1G and BCW33LT1G have 32 V breakdown voltage instead of 30 V?

A: BCW32 and BCW33 series devices are rated for 32 V collector-emitter breakdown voltage, which exceeds the FMMT449 specification of 30 V. This higher rating provides additional voltage margin and does not prevent substitution in 30 V applications.

Q: Can BCW65ALT1G fully replace the FMMT449?

A: BCW65ALT1G provides 800 mA maximum collector current, which approaches but does not fully match the FMMT449 specification of 1 A. This device is suitable for applications requiring current levels up to 800 mA. Applications requiring the full 1 A specification cannot be satisfied by BCW65ALT1G.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All identified substitute parts are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, matching the FMMT449 environmental and regulatory specifications.

Q: What is the significance of transition frequency differences between FMMT449 (150 MHz) and substitute parts (100 MHz)?

A: The FMMT449 specifies 150 MHz transition frequency, while most BC848 and BC849 series devices specify 100 MHz. BCW65ALT1G also specifies 100 MHz. BCW32LT1G and BCW33LT1G do not specify transition frequency. Lower transition frequency may limit high-frequency switching applications. Applications operating below 100 MHz are unaffected.

Q: Is the SOT-23-3 package identical across all listed parts?

A: Yes. All parts use SOT-23-3 (also designated TO-236-3 or SC-59) surface mount package with identical pinout and footprint compatibility.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message