MMBT3904T-7 Equivalent & Substitute Parts

Part Overview

The MMBT3904T-7 is a surface mount NPN bipolar junction transistor manufactured by Diodes Incorporated in SOT-523 package. This device is rated for 40 V collector-emitter breakdown voltage, 200 mA maximum collector current, and 150 mW power dissipation. The part is classified as obsolete, which necessitates identification of active equivalent and substitute components for ongoing design support and procurement.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	150	mW
Frequency - Transition	300	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10mA, 1V	—
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 50mA	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	SOT-523	—

Substitute Part Grouping Explanation

Substitution of the MMBT3904T-7 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Transistor Type: NPN
Voltage - Collector Emitter Breakdown (Max): 40 V minimum
Current - Collector (Ic) (Max): 200 mA minimum
DC Current Gain (hFE) (Min) @ Ic, Vce: 100 @ 10mA, 1V minimum
Vce Saturation (Max) @ Ib, Ic: 300mV @ 5mA, 50mA maximum
Frequency - Transition: 300 MHz minimum
Operating Temperature Range: -55°C to 150°C minimum

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount
Package / Case: SOT-523 or equivalent footprint-compatible packages (SOT-23, SOT-323, SC-75)

Substitute parts are grouped into two categories:

Category 1: Direct Electrical and Package Equivalents Parts maintaining identical electrical specifications and SOT-523 package footprint.

Category 2: Functional Equivalents with Package Variants Parts meeting or exceeding electrical specifications but utilizing alternative surface mount packages (SOT-23, SOT-323, SC-75) that require PCB layout modification.

Category 3: Partial Specification Matches Parts meeting core electrical requirements but with reduced maximum collector current or transition frequency, suitable only for reduced-performance applications.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce Breakdown (Max) V	Power (Max) mW	Frequency MHz	hFE (Min)	Package	RoHS Status
MMBT3904T-7	Diodes Incorporated	Obsolete	200	40	150	300	100	SOT-523	Non-compliant
MMBT3904T-7-F	Diodes Incorporated	Active	200	40	150	300	100	SOT-523	ROHS3 Compliant
MMBT3904T-TP	Micro Commercial Co	Active	200	40	150	300	100	SOT-523	ROHS3 Compliant
CMUT3904 TR PBFREE	Central Semiconductor Corp	Active	200	40	250	300	100	SOT-523	ROHS3 Compliant
MMST3904-7-F	Diodes Incorporated	Active	200	40	200	300	100	SOT-323	ROHS3 Compliant
MMST3904-TP	Micro Commercial Co	Active	200	40	200	300	100	SOT-323	ROHS3 Compliant
MMBT3904-TP	Micro Commercial Co	Active	200	40	350	300	100	SOT-23	ROHS3 Compliant
MMBT3904TT1G	onsemi	Active	200	40	300	300	100	SC-75, SOT-416	ROHS3 Compliant
BSR17A	onsemi	Active	200	40	350	300	100	SOT-23-3	ROHS3 Compliant
MMBT2222AT-TP	Micro Commercial Co	Active	600	40	150	300	75	SOT-523	ROHS3 Compliant
PMBS3904,215	Nexperia USA Inc.	Active	100	40	250	180	100	TO-236AB	ROHS3 Compliant

Engineering Selection Recommendations

Primary Substitutes (Direct Equivalents):

MMBT3904T-7-F (Diodes Incorporated) and MMBT3904T-TP (Micro Commercial Co) are direct electrical and mechanical equivalents. Both maintain identical electrical specifications and SOT-523 package compatibility. Both parts are active products with ROHS3 compliance, providing immediate procurement viability for designs currently using the obsolete MMBT3904T-7.

Secondary Substitutes (Package Variants with Enhanced Specifications):

MMST3904-7-F (Diodes Incorporated) and MMST3904-TP (Micro Commercial Co) provide identical electrical performance with increased power dissipation capability (200 mW versus 150 mW). These parts utilize SOT-323 package, requiring PCB layout modification but offering improved thermal performance.

MMBT3904-TP (Micro Commercial Co) and BSR17A (onsemi) provide identical electrical performance with significantly increased power dissipation (350 mW). These parts utilize SOT-23 package, requiring PCB layout modification.

MMBT3904TT1G (onsemi) provides identical electrical performance with 300 mW power dissipation in SC-75/SOT-416 package, requiring PCB layout modification.

Tertiary Substitutes (Partial Specification Matches):

CMUT3904 TR PBFREE (Central Semiconductor Corp) maintains identical electrical specifications in SOT-523 package with enhanced power dissipation (250 mW) and extended lower operating temperature (-65°C versus -55°C).

PMBS3904,215 (Nexperia USA Inc.) provides reduced maximum collector current (100 mA versus 200 mA) and reduced transition frequency (180 MHz versus 300 MHz). This part is suitable only for applications with reduced current and frequency requirements.

MMBT2222AT-TP (Micro Commercial Co) provides increased maximum collector current (600 mA) but reduced DC current gain (75 versus 100). This part is suitable for applications requiring higher current capacity with modified gain characteristics.

Compliance Considerations:

The original MMBT3904T-7 is RoHS non-compliant. All recommended substitutes are ROHS3 compliant, meeting current environmental and regulatory requirements. All substitute parts maintain AEC-Q101 automotive qualification or equivalent reliability standards where applicable.

Frequently Asked Questions (FAQ)

Q: Can MMBT3904T-7-F directly replace MMBT3904T-7 without PCB modification?

A: Yes. MMBT3904T-7-F is a direct equivalent with identical electrical specifications and SOT-523 package footprint. No PCB layout changes are required.

Q: What is the difference between MMBT3904T-7-F and MMST3904-7-F?

A: Both parts are manufactured by Diodes Incorporated with identical electrical specifications. The primary difference is package: MMBT3904T-7-F uses SOT-523, while MMST3904-7-F uses SOT-323. MMST3904-7-F provides higher power dissipation (200 mW versus 150 mW) but requires PCB layout modification.

Q: Can I use MMBT3904-TP (SOT-23 package) as a substitute for MMBT3904T-7 (SOT-523 package)?

A: MMBT3904-TP provides identical electrical specifications and enhanced power dissipation (350 mW). However, SOT-23 and SOT-523 packages have different footprints and pin configurations. PCB layout modification is required.

Q: Is PMBS3904,215 suitable for all applications using MMBT3904T-7?

A: No. PMBS3904,215 has reduced maximum collector current (100 mA versus 200 mA) and reduced transition frequency (180 MHz versus 300 MHz). This part is suitable only for applications with current requirements not exceeding 100 mA and frequency requirements not exceeding 180 MHz.

Q: What is the advantage of CMUT3904 TR PBFREE over MMBT3904T-7-F?

A: CMUT3904 TR PBFREE maintains identical electrical specifications with enhanced power dissipation (250 mW versus 150 mW) and extended lower operating temperature range (-65°C versus -55°C). Both parts use SOT-523 package.

Q: Are all substitute parts RoHS compliant?

A: Yes. All recommended substitute parts are ROHS3 compliant. The original MMBT3904T-7 is RoHS non-compliant.

Q: Can MMBT2222AT-TP replace MMBT3904T-7 in high-current applications?

A: MMBT2222AT-TP provides higher maximum collector current (600 mA) but with reduced DC current gain (75 versus 100). This part is suitable for applications requiring higher current capacity where the reduced gain characteristic is acceptable. Both parts use SOT-523 package.

Q: What is the difference between Tape & Reel (TR) and Cut Tape (CT) packaging?

A: Tape & Reel packaging supplies components on continuous tape suitable for automated pick-and-place assembly. Cut Tape & Digi-Reel packaging supplies components on tape segments or reel formats. Both formats are compatible with standard surface mount assembly processes. Selection depends on production volume and assembly equipment capability.

Q: Do all substitute parts maintain the same thermal characteristics?

A: No. Power dissipation ratings vary among substitutes. MMBT3904T-7 and MMBT3904T-TP are rated at 150 mW. MMST3904-7-F and MMST3904-TP are rated at 200 mW. MMBT3904-TP and BSR17A are rated at 350 mW. CMUT3904 TR PBFREE is rated at 250 mW. Higher power ratings indicate improved thermal performance.

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