MMBT3904LT3XT Equivalent & Substitute Parts

Part Overview

The MMBT3904LT3XT is a Surface Mount NPN Bipolar Junction Transistor manufactured by Infineon Technologies in SOT-23-3 package configuration. This component is rated for 40V collector-emitter breakdown voltage with 200mA maximum collector current and 300MHz transition frequency. The part is currently discontinued at DiGi Electronics, necessitating identification of equivalent substitute components that maintain electrical and mechanical compatibility for existing designs and new production requirements.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Collector-Emitter Breakdown Voltage (Max)	40	V
Collector Current (Max)	200	mA
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 50mA	—
Collector Cutoff Current (Max)	50	nA
DC Current Gain (hFE Min) @ Ic, Vce	100 @ 10mA, 1V	—
Power Dissipation (Max)	330	mW
Transition Frequency	300	MHz
Operating Temperature (Max)	150	°C
Package Type	SOT-23-3 (TO-236-3, SC-59)	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute components for the MMBT3904LT3XT are classified based on strict electrical and mechanical parameter alignment. The primary substitution criteria are:

Critical Parameters for Substitution:

Transistor Type: NPN
Collector-Emitter Breakdown Voltage: 40V minimum
Collector Current Rating: 200mA minimum
DC Current Gain (hFE): 100 minimum @ 10mA, 1V
Transition Frequency: 300MHz minimum
Package: SOT-23-3 (TO-236-3, SC-59) Surface Mount
RoHS3 Compliance
Moisture Sensitivity Level: 1

Secondary Parameters (Allowable Variation):

Power Dissipation: 200mW to 350mW (original 330mW)
Vce Saturation: 200mV to 300mV @ specified conditions
Collector Cutoff Current: 5nA to 100nA
Operating Temperature Range: Minimum -55°C to -65°C; Maximum 150°C

Substitute parts are grouped into two categories: Parametric Equivalents (same manufacturer, different packaging or product status) and Direct Manufacturer Equivalents (alternative manufacturers meeting all electrical specifications).

Parameter Comparison

Part Number	Manufacturer	Ic (Max) mA	Vce(br) V	Vce Sat mV	hFE Min	Freq MHz	Power mW	Temp °C	Package	Status
MMBT3904LT3XT	Infineon	200	40	300	100	300	330	150	SOT-23-3	Discontinued
MMBT3904LT1HTSA1	Infineon	200	40	300	100	300	330	150	SOT-23-3	Last Time Buy
SMBT3904E6327HTSA1	Infineon	200	40	300	100	300	330	150	SOT-23-3	Last Time Buy
BSR17A	onsemi	200	40	300	100	300	350	150	SOT-23-3	Active
CMPT3904E TR PBFREE	Central Semiconductor	200	40	200	100	300	350	150	SOT-23-3	Active
CMPT3904G TR PBFREE	Central Semiconductor	200	40	300	100	300	350	150	SOT-23-3	Active
MMBT3904,215	Nexperia USA Inc.	200	40	300	100	300	250	150	SOT-23-3	Active
MMBT3904-7-F	Diodes Incorporated	200	40	300	100	300	300	150	SOT-23-3	Active
MMBT3904-G	Comchip Technology	200	40	300	100	300	200	150	SOT-23-3	Active
MMBT3904-HF	Comchip Technology	200	40	300	100	300	200	150	SOT-23-3	Active
MMBT3904-TP	Micro Commercial Co	200	40	300	100	300	350	150	SOT-23-3	Active

Engineering Selection Recommendations

Infineon Parametric Equivalents (Recommended for Existing Designs):

MMBT3904LT1HTSA1 and SMBT3904E6327HTSA1 maintain identical electrical specifications to the original MMBT3904LT3XT. Both are Infineon products with Last Time Buy status, indicating limited availability. MMBT3904LT1HTSA1 offers 51,507 units in stock with Cut Tape packaging, while SMBT3904E6327HTSA1 provides 253,664 units in stock. These are optimal for designs requiring minimal qualification effort due to manufacturer continuity.

Active Production Alternatives (Recommended for New Designs):

MMBT3904-7-F (Diodes Incorporated) and MMBT3904-TP (Micro Commercial Co) are both in active production with substantial inventory levels (185,200 and 515,100 units respectively). Both meet all electrical parameters and carry AEC-Q101 automotive qualification where applicable. MMBT3904-7-F includes automotive grade certification; MMBT3904-TP offers the highest inventory availability.

Alternative Manufacturers:

BSR17A (onsemi) and CMPT3904G TR PBFREE (Central Semiconductor) provide direct functional equivalence with active production status. BSR17A offers extended operating temperature range (-55°C to 150°C) and 119,200 units in stock. CMPT3904G provides 2,434 units with identical Vce saturation specification (300mV).

Nexperia Option:

MMBT3904,215 (Nexperia USA Inc.) is active production with automotive AEC-Q101 qualification. Power dissipation is rated at 250mW, which is lower than the original 330mW specification but remains within acceptable design margins for most applications.

Comchip Technology Options:

MMBT3904-G and MMBT3904-HF both offer active production status with extended temperature range (-55°C to 150°C). Power dissipation is rated at 200mW. MMBT3904-HF specifies collector cutoff current at 100nA versus the original 50nA specification.

Frequently Asked Questions (FAQ)

Q: Can MMBT3904LT1HTSA1 directly replace MMBT3904LT3XT in production?

A: Yes. MMBT3904LT1HTSA1 is a parametric equivalent from the same manufacturer (Infineon) with identical electrical specifications. The primary difference is packaging format (Cut Tape versus Tape & Reel). Both are SOT-23-3 surface mount packages with identical pin configuration and electrical performance. Verify tape reel compatibility with your assembly equipment.

Q: What is the difference between MMBT3904-7-F and MMBT3904-TP?

A: Both parts are functionally equivalent NPN transistors meeting the 40V/200mA/300MHz specification. MMBT3904-7-F is manufactured by Diodes Incorporated with AEC-Q101 automotive qualification and 185,200 units available. MMBT3904-TP is manufactured by Micro Commercial Co with 515,100 units available. Selection depends on supply chain preference and automotive qualification requirements.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts carry ROHS3 Compliance certification and Moisture Sensitivity Level 1 (Unlimited), matching the original MMBT3904LT3XT specifications.

Q: Can I use BSR17A as a substitute if my design operates at -55°C?

A: Yes. BSR17A supports operating temperature range of -55°C to 150°C, which exceeds the original MMBT3904LT3XT specification of 150°C maximum. All other electrical parameters are equivalent. Verify that your PCB assembly process is compatible with onsemi's BSR17A package specifications.

Q: What is the significance of "Last Time Buy" status for MMBT3904LT1HTSA1?

A: Last Time Buy status indicates that Infineon will discontinue this part after current inventory is exhausted. While 51,507 units are currently in stock, this part should not be selected for new long-term production designs. Use for existing design support or transition to active production alternatives such as MMBT3904-7-F or MMBT3904-TP.

Q: Does lower power dissipation rating (200mW vs 330mW) affect circuit performance?

A: Power dissipation rating indicates maximum allowable thermal stress. Lower ratings (MMBT3904-G, MMBT3904-HF at 200mW) are conservative specifications. If your circuit design dissipates less than 200mW in the transistor, these parts are suitable. If your design approaches or exceeds 200mW, select parts with 300mW or 350mW ratings (MMBT3904-7-F, MMBT3904-TP, BSR17A).

Q: Are there any differences in Vce saturation between substitute parts?

A: Yes. Most substitutes specify 300mV Vce saturation @ 5mA, 50mA (matching the original). CMPT3904E TR PBFREE specifies 200mV, which is lower and represents improved saturation performance. This difference is not significant for most switching applications but may affect linear amplifier designs operating near saturation.

Q: Can I mix different manufacturers in the same production batch?

A: All listed parts meet identical electrical specifications and SOT-23-3 package requirements. Mixing manufacturers in the same batch is technically feasible from an electrical standpoint. However, verify with your quality assurance procedures regarding supplier qualification, traceability requirements, and any design documentation that may specify single-source components.

Q: What packaging formats are available for substitutes?

A: Substitute parts are available in Tape & Reel (TR) and Cut Tape (CT) formats. MMBT3904LT3XT was originally Tape & Reel. MMBT3904LT1HTSA1 and SMBT3904E6327HTSA1 are Cut Tape. Most active production alternatives (MMBT3904-7-F, MMBT3904-TP) offer Cut Tape & Digi-Reel® format. Confirm your pick-and-place equipment compatibility with the selected packaging format.

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