MMBT3904_D87Z Equivalent & Substitute Parts

Part Overview

The MMBT3904_D87Z is an NPN bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features a 40 V collector-emitter breakdown voltage, 200 mA maximum collector current, and 300 MHz transition frequency in a surface mount SOT-23-3 package. The part is classified as obsolete, necessitating identification of active equivalent and substitute components for new designs and production continuity.

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	300mV @ 5mA, 50mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10mA, 1V	—
Power - Max	350	mW
Frequency - Transition	300	MHz
Operating Temperature Range	-55 to 150	°C
Package / Case	SOT-23-3 (TO-236-3, SC-59)	—
Mounting Type	Surface Mount	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the MMBT3904_D87Z is determined by strict electrical and mechanical parameter matching within the NPN bipolar transistor category. The critical parameters governing substitution are:

Electrical Parameters:

Voltage - Collector Emitter Breakdown: 40 V minimum
Current - Collector (Max): 200 mA minimum
DC Current Gain (hFE): 100 minimum @ 10mA, 1V
Frequency - Transition: 300 MHz minimum
Power dissipation capability: 300 mW minimum

Mechanical Parameters:

Package / Case: SOT-23-3 (TO-236-3, SC-59)
Mounting Type: Surface Mount
Moisture Sensitivity Level: 1 (Unlimited)

Substitution Categories:

Direct Equivalents maintain all electrical specifications and package requirements, differing only in manufacturer, product status (active vs. obsolete), or minor packaging variants (tape & reel vs. cut tape).

Similar Parts share the same base electrical specifications but may include automotive-grade qualifications (AEC-Q101) or enhanced temperature ranges, making them suitable for applications requiring higher reliability standards.

Parameter Comparison

Part Number	Manufacturer	Product Status	Ic (Max) mA	Vce(br) V	Vce Sat @ Ib, Ic	hFE (Min) @ Ic, Vce	Power (Max) mW	Freq (MHz)	Temp Range °C	Package	RoHS
MMBT3904_D87Z	onsemi	Obsolete	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	350	300	-55 to 150	SOT-23-3	—
BSR17A	onsemi	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	350	300	-55 to 150	SOT-23-3	ROHS3
MMBT3904LT1G	onsemi	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	300	300	-55 to 150	SOT-23-3	ROHS3
SMMBT3904LT1G	onsemi	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	300	300	-55 to 150	SOT-23-3	ROHS3
SMMBT3904LT3G	onsemi	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	300	300	-55 to 150	SOT-23-3	ROHS3
MMBT3904LT3G	onsemi	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	300	300	-55 to 150	SOT-23-3	ROHS3
CMPT3904E TR PBFREE	Central Semiconductor Corp	Active	200	40	200mV @ 5mA, 50mA	100 @ 10mA, 1V	350	300	-65 to 150	SOT-23-3	ROHS3
CMPT3904G TR PBFREE	Central Semiconductor Corp	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	350	300	-65 to 150	SOT-23-3	ROHS3
MMBT3904,215	Nexperia USA Inc.	Active	200	40	300mV @ 5mA, 50mA	100 @ 10mA, 1V	250	300	-55 to 150	SOT-23-3	ROHS3

Engineering Selection Recommendations

Primary Substitutes (Direct Equivalents):

The following parts are direct functional equivalents with active product status and full compliance certifications:

BSR17A (onsemi): Identical electrical specifications to the MMBT3904_D87Z with ROHS3 compliance. Active product status with high inventory availability (119,200 pcs).
MMBT3904LT1G (onsemi): Active equivalent with ROHS3 compliance. Packaging specified as Cut Tape & Digi-Reel. Inventory: 605,100 pcs.
MMBT3904LT3G (onsemi): Active equivalent with ROHS3 compliance. Packaging specified as Cut Tape & Digi-Reel. Inventory: 360,300 pcs.

Automotive-Grade Substitutes:

For applications requiring automotive qualification (AEC-Q101):

SMMBT3904LT1G (onsemi): Automotive-grade NPN transistor with AEC-Q101 qualification. Identical electrical specifications. Inventory: 287,300 pcs.
SMMBT3904LT3G (onsemi): Automotive-grade NPN transistor with AEC-Q101 qualification. Identical electrical specifications. Inventory: 400,400 pcs.
MMBT3904,215 (Nexperia USA Inc.): Automotive-grade with AEC-Q101 qualification. Power rating 250 mW (lower than original 350 mW). Limited inventory (4,100 pcs).

Alternative Manufacturer Substitutes:

CMPT3904G TR PBFREE (Central Semiconductor Corp): Active equivalent with extended temperature range (-65°C to 150°C). ROHS3 compliant. Inventory: 2,434 pcs.
CMPT3904E TR PBFREE (Central Semiconductor Corp): Active equivalent with extended temperature range (-65°C to 150°C) and improved Vce saturation (200mV). ROHS3 compliant. Inventory: 140,270 pcs.

Selection Criteria:

For standard applications, select from onsemi MMBT3904LT1G or MMBT3904LT3G based on packaging requirements and inventory needs. For automotive applications, select SMMBT3904LT1G or SMMBT3904LT3G. For extended temperature operation, select CMPT3904E TR PBFREE or CMPT3904G TR PBFREE from Central Semiconductor Corp.

Frequently Asked Questions (FAQ)

Q: Can MMBT3904LT1G directly replace MMBT3904_D87Z in existing designs?

A: Yes. MMBT3904LT1G maintains identical electrical specifications (40 V, 200 mA, 300 MHz, 100 hFE minimum) and SOT-23-3 package. The primary difference is product status (active vs. obsolete) and ROHS3 compliance certification.

Q: What is the difference between MMBT3904LT1G and SMMBT3904LT1G?

A: SMMBT3904LT1G includes automotive-grade qualification (AEC-Q101) and is designated for automotive applications. Electrical specifications are identical. SMMBT3904LT1G is suitable for applications requiring automotive reliability standards.

Q: Are there any power dissipation differences between substitutes?

A: Yes. Most onsemi substitutes (MMBT3904LT1G, SMMBT3904LT1G, SMMBT3904LT3G, MMBT3904LT3G) specify 300 mW maximum power, compared to the original 350 mW. CMPT3904E and CMPT3904G maintain 350 mW. MMBT3904,215 specifies 250 mW. Verify power dissipation requirements in your application before selection.

Q: What is the significance of the "LT1G" and "LT3G" suffixes?

A: These suffixes indicate packaging and tape configuration variants. Both LT1G and LT3G are supplied in Cut Tape & Digi-Reel format. The numeric difference (1 vs. 3) reflects internal onsemi manufacturing designations and does not affect electrical performance or compatibility.

Q: Can CMPT3904 parts from Central Semiconductor Corp be used as direct replacements?

A: Yes, with considerations. CMPT3904E TR PBFREE and CMPT3904G TR PBFREE maintain all critical electrical specifications and SOT-23-3 packaging. Both offer extended temperature range (-65°C to 150°C vs. -55°C to 150°C). CMPT3904E provides improved Vce saturation (200mV vs. 300mV), which may affect switching performance in saturation-mode applications.

Q: Is RoHS compliance a requirement for substitution?

A: ROHS3 compliance is standard across all active substitutes listed. The original MMBT3904_D87Z does not specify RoHS status. If RoHS compliance is required for your application, all listed active substitutes meet this requirement.

Q: What inventory considerations should guide part selection?

A: MMBT3904LT1G offers the highest inventory (605,100 pcs), followed by SMMBT3904LT3G (400,400 pcs) and MMBT3904LT3G (360,300 pcs). For long-term supply assurance, these three options provide the best availability. MMBT3904,215 has limited inventory (4,100 pcs) and should be selected only when automotive qualification is mandatory.

Q: Are there electrical performance differences in switching speed between substitutes?

A: All substitutes maintain 300 MHz transition frequency, identical to the original part. Switching speed performance is equivalent across all listed direct equivalents and automotive-grade variants.

Q: Can SMMBT4401LT1G or MMBT6429LT1G be used as substitutes?

A: No. SMMBT4401LT1G specifies 600 mA maximum collector current (3× higher than MMBT3904_D87Z) and is designed for higher-current applications. MMBT6429LT1G specifies 45 V breakdown voltage and 700 MHz transition frequency, representing a different device class. These parts are not direct substitutes and should not be used for MMBT3904_D87Z replacement.

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