MMBT3904-7 Equivalent & Substitute Parts

Part Overview

The MMBT3904-7 is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for general-purpose switching and amplification applications. The device is rated for 40 V collector-emitter breakdown voltage with a maximum collector current of 200 mA and operates across a temperature range of -55°C to 150°C. The part is packaged in SOT-23-3 (TO-236-3, SC-59) surface mount configuration with 300 mW maximum power dissipation and 300 MHz transition frequency.

The MMBT3904-7 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 compatible performance within defined parameter tolerances suitable for direct board-level replacement.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	200	mA
Vce Saturation (Max) @ Ib, Ic	300 mV @ 5 mA, 50 mA	—
Current - Collector Cutoff (Max)	50	nA (ICBO)
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10 mA, 1 V	—
Power - Max	300	mW
Frequency - Transition	300	MHz
Operating Temperature	-55 to 150	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Grade	Automotive	—
Qualification	AEC-Q101	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMBT3904-7 is determined by electrical parameter compatibility and mechanical package equivalence. The critical parameters governing substitution are:

Electrical Parameters:

Collector-emitter breakdown voltage: 40 V minimum
Maximum collector current: 200 mA minimum
DC current gain (hFE): 100 minimum at specified bias conditions
Transition frequency: 300 MHz minimum
Power dissipation: 300 mW minimum
Saturation voltage: 300 mV maximum at specified conditions

Mechanical Parameters:

Package type: SOT-23-3 (TO-236-3, SC-59) surface mount configuration
Moisture sensitivity: MSL 1 (Unlimited)
Lead-free (RoHS3 compliant) preferred for new designs

Compliance Parameters:

Automotive grade with AEC-Q101 qualification preferred
REACH unaffected status required

Substitute parts are categorized as follows:

Parametric Equivalents: Parts with identical electrical specifications and active product status, offering direct replacement capability.

Direct Manufacturer Equivalents: Parts from alternative manufacturers meeting or exceeding all electrical parameters with compatible packaging.

Upgrade Options: Parts with enhanced specifications (higher power rating, extended temperature range, or improved performance metrics) suitable for applications requiring additional design margin.

Manufacturer Recommended Alternatives: Parts with modified electrical specifications (higher voltage or current ratings) for applications where the original specifications exceed actual circuit requirements.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce(br) V	Power mW	Freq MHz	Temp °C	Package	RoHS	AEC-Q101
MMBT3904-7	Diodes Inc.	Obsolete	200	40	300	300	-55 to 150	SOT-23-3	Non-compliant	Yes
MMBT3904-7-F	Diodes Inc.	Active	200	40	300	300	-55 to 150	SOT-23-3	ROHS3	Yes
CMPT3904G TR PBFREE	Central Semiconductor	Active	200	40	350	300	-65 to 150	SOT-23	ROHS3	No
SMMBT3904LT1G	onsemi	Active	200	40	300	300	-55 to 150	SOT-23-3	ROHS3	Yes
SMMBT3904LT3G	onsemi	Active	200	40	300	300	-55 to 150	SOT-23-3	ROHS3	Yes
MMBT3904,215	Nexperia USA Inc.	Active	200	40	250	300	-55 to 150	TO-236AB	ROHS3	Yes
SMBT3904E6327HTSA1	Infineon	Last Time Buy	200	40	330	300	-55 to 150	PG-SOT23	ROHS3	No
BC817-16,215	Nexperia USA Inc.	Active	500	45	250	100	-55 to 150	TO-236AB	ROHS3	Yes
BC817-16,235	Nexperia USA Inc.	Active	500	45	250	100	-55 to 150	TO-236AB	ROHS3	Yes
BC817-16LT1G	onsemi	Active	500	45	300	100	-65 to 150	SOT-23-3	ROHS3	No
BC817-16LT3G	onsemi	Active	500	45	300	100	-65 to 150	SOT-23-3	ROHS3	No

Engineering Selection Recommendations

Primary Equivalent Selection:

For direct replacement of MMBT3904-7 in active production, MMBT3904-7-F from Diodes Incorporated is the primary choice. This part maintains identical electrical specifications and automotive AEC-Q101 qualification while offering active product status and RoHS3 compliance. The parametric equivalence ensures pin-for-pin compatibility with no circuit redesign required.

Alternative Equivalents with Active Status:

SMMBT3904LT1G and SMMBT3904LT3G from onsemi provide full electrical and mechanical equivalence to the original part. Both devices maintain the 40 V breakdown voltage, 200 mA collector current, 300 mW power rating, and 300 MHz transition frequency. These parts carry automotive AEC-Q101 qualification and RoHS3 compliance. The primary distinction between LT1G and LT3G variants relates to packaging format (Cut Tape vs. Tape & Reel), with no electrical differences.

Enhanced Performance Option:

CMPT3904G TR PBFREE from Central Semiconductor offers increased power dissipation (350 mW vs. 300 mW) and extended lower operating temperature limit (-65°C vs. -55°C). This part maintains all critical electrical parameters and is suitable for applications requiring additional thermal margin. Note that this device does not carry AEC-Q101 automotive qualification.

Upgrade Consideration:

MMBT3904,215 from Nexperia USA Inc. provides automotive-grade AEC-Q101 qualification with identical electrical performance. The 250 mW power rating is lower than the original specification but remains adequate for most general-purpose switching applications. This part is suitable for cost-optimized designs where the reduced power rating does not impact circuit performance.

Last Time Buy Status:

SMBT3904E6327HTSA1 from Infineon is designated Last Time Buy, indicating discontinued production with limited inventory availability. This part offers enhanced 330 mW power dissipation but should not be selected for new designs due to supply constraints.

Manufacturer Recommended Alternatives:

BC817-16 series devices from Nexperia USA Inc. and onsemi represent higher-performance alternatives with 500 mA collector current and 45 V breakdown voltage. These parts are suitable for applications where the MMBT3904-7 specifications exceed actual circuit requirements. The BC817-16 series exhibits lower transition frequency (100 MHz vs. 300 MHz), which may impact high-frequency switching performance. Selection of BC817-16 variants should be limited to applications where the reduced frequency response is acceptable and the higher current capability provides design margin.

Frequently Asked Questions (FAQ)

Q: Can MMBT3904-7-F be used as a direct replacement for MMBT3904-7?

A: Yes. MMBT3904-7-F maintains identical electrical specifications including 40 V breakdown voltage, 200 mA maximum collector current, 300 mW power dissipation, and 300 MHz transition frequency. The part is packaged in the same SOT-23-3 configuration with identical pin assignments. MMBT3904-7-F is active product status with RoHS3 compliance, making it the preferred direct replacement.

Q: What is the difference between SMMBT3904LT1G and SMMBT3904LT3G?

A: Both parts are electrically identical with the same 40 V breakdown voltage, 200 mA collector current, 300 mW power rating, and 300 MHz transition frequency. The designation suffix indicates packaging format: LT1G is supplied in Cut Tape with Digi-Reel format, while LT3G is supplied in standard Tape & Reel format. Selection between these variants depends on procurement and assembly requirements rather than electrical performance.

Q: Can BC817-16 series devices replace MMBT3904-7?

A: BC817-16 devices are electrically compatible but represent an upgrade rather than a direct equivalent. The BC817-16 series offers higher collector current (500 mA vs. 200 mA) and higher breakdown voltage (45 V vs. 40 V), providing additional design margin. However, the transition frequency is reduced to 100 MHz compared to 300 MHz for MMBT3904-7. BC817-16 selection is appropriate only for applications where the lower frequency response does not impact circuit performance and where the higher current capability is beneficial.

Q: Is automotive AEC-Q101 qualification required for my application?

A: Automotive AEC-Q101 qualification is mandatory for components used in automotive applications subject to automotive industry standards. For non-automotive applications, parts without AEC-Q101 qualification (such as CMPT3904G TR PBFREE or BC817-16LT1G) are acceptable. Verify application requirements before selecting non-qualified alternatives.

Q: What is the significance of RoHS3 compliance?

A: RoHS3 compliance indicates the part meets Restriction of Hazardous Substances regulations, restricting lead and other hazardous materials. MMBT3904-7 is RoHS non-compliant, while all active substitute parts listed are RoHS3 compliant. For new designs and applications subject to environmental regulations, RoHS3 compliant parts are required. MMBT3904-7-F, SMMBT3904LT1G, SMMBT3904LT3G, MMBT3904,215, and BC817 series variants all meet RoHS3 requirements.

Q: Can CMPT3904G TR PBFREE be used in automotive applications?

A: CMPT3904G TR PBFREE does not carry AEC-Q101 automotive qualification. While the part meets electrical specifications and RoHS3 compliance, it is not qualified for automotive applications requiring AEC-Q101 certification. Use this part only in non-automotive applications or where automotive qualification is not mandated.

Q: What is Last Time Buy status and why is SMBT3904E6327HTSA1 designated this way?

A: Last Time Buy status indicates the manufacturer has announced end-of-life production with a final order cutoff date. SMBT3904E6327HTSA1 is no longer in active production, and inventory is limited. This part should not be selected for new designs. Existing designs using this part should transition to active alternatives such as MMBT3904-7-F or SMMBT3904LT1G to ensure long-term supply availability.

Q: Are there any package differences between substitute parts?

A: Most substitute parts use SOT-23-3 (TO-236-3, SC-59) packaging identical to MMBT3904-7. MMBT3904,215 uses TO-236AB packaging, which is mechanically compatible with SOT-23-3 but may have minor dimensional variations. CMPT3904G TR PBFREE uses SOT-23 packaging, which is functionally equivalent but may have slight footprint differences. Verify PCB footprint compatibility before selecting parts with package designation variations.

Q: What is the operating temperature range difference between parts?

A: MMBT3904-7 operates from -55°C to 150°C. CMPT3904G TR PBFREE extends the lower limit to -65°C, providing operation in more extreme cold environments. BC817-16LT1G and BC817-16LT3G also support -65°C minimum temperature. For applications requiring extended low-temperature operation, these alternatives provide additional capability. Most other substitutes maintain the -55°C to 150°C range.

Q: What power dissipation differences exist among substitute parts?

A: MMBT3904-7 is rated for 300 mW maximum power dissipation. CMPT3904G TR PBFREE offers 350 mW, providing 17% additional thermal capacity. SMBT3904E6327HTSA1 provides 330 mW. MMBT3904,215 is rated for 250 mW, which is lower than the original but adequate for most general-purpose switching applications. BC817-16 series devices are rated for 250-300 mW depending on variant. Select parts with higher power ratings for applications with marginal thermal design.

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