MMBT4400 Equivalent & Substitute Parts

Part Overview

The MMBT4400 is an NPN bipolar junction transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This device is rated for 40 V collector-emitter breakdown voltage and 600 mA maximum collector current, with a maximum power dissipation of 350 mW. The MMBT4400 is classified as obsolete, necessitating identification of active substitute components for new designs and ongoing production requirements. Substitute parts must maintain electrical compatibility within the specified parameter ranges while offering active product status and current manufacturing availability.

Key Parameters

Parameter	MMBT4400 Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	600	mA
Power - Max	350	mW
Vce Saturation (Max) @ Ib, Ic	750mV @ 50mA, 500mA	V
DC Current Gain (hFE) (Min) @ Ic, Vce	50 @ 150mA, 10V	—
Operating Temperature	-55 to 150	°C
Package / Case	SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitute parts for the MMBT4400 are selected based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Critical Compatibility Parameters:

Transistor Type: NPN (must match)
Package / Case: SOT-23-3 (must match for mechanical compatibility)
Mounting Type: Surface Mount (must match)
Voltage - Collector Emitter Breakdown: Must equal or exceed 40 V
Current - Collector (Ic) (Max): Must equal or exceed 600 mA
Power - Max: Must equal or exceed 350 mW

Substitute parts are grouped into two categories based on collector current rating:

Category A - Full Current Rating (500 mA to 600 mA): BC817 series variants (BC817-16LT1G, BC817-16LT3G, BC817-25LT1G, BC817-25LT3G, BC817-40LT1G, BC817-40LT3G) provide 500 mA maximum collector current with 45 V breakdown voltage and 300 mW power rating. These parts meet or exceed the voltage and power requirements but operate at reduced maximum collector current.

Category B - Reduced Current Rating (100 mA): BC847 series variants (BC847ALT1G, BC847BLT1G, BC847BLT3G, BC847CLT1G) provide only 100 mA maximum collector current and are suitable only for applications where collector current does not exceed 100 mA.

All substitute parts are active products with RoHS3 compliance and unlimited moisture sensitivity level (MSL 1).

Parameter Comparison

Parameter	MMBT4400	BC817-16LT1G	BC817-25LT1G	BC817-40LT1G	BC847ALT1G	BC847BLT1G	BC847CLT1G
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	40 V	45 V	45 V	45 V	45 V	45 V	45 V
Current - Collector (Ic) (Max)	600 mA	500 mA	500 mA	500 mA	100 mA	100 mA	100 mA
Power - Max	350 mW	300 mW	300 mW	300 mW	300 mW	300 mW	300 mW
Vce Saturation (Max) @ Ib, Ic	750mV @ 50mA, 500mA	700mV @ 50mA, 500mA	700mV @ 50mA, 500mA	700mV @ 50mA, 500mA	600mV @ 5mA, 100mA	600mV @ 5mA, 100mA	600mV @ 5mA, 100mA
DC Current Gain (hFE) (Min)	50 @ 150mA, 10V	100 @ 100mA, 1V	160 @ 100mA, 1V	250 @ 100mA, 1V	110 @ 2mA, 5V	200 @ 2mA, 5V	420 @ 2mA, 5V
Frequency - Transition	—	100 MHz	100 MHz	100 MHz	100 MHz	100 MHz	100 MHz
Operating Temperature	-55 to 150°C	-65 to 150°C	-65 to 150°C	-65 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C
Package / Case	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Applications Requiring 500 mA to 600 mA Collector Current:

The BC817 series (BC817-16LT1G, BC817-16LT3G, BC817-25LT1G, BC817-25LT3G, BC817-40LT1G, BC817-40LT3G) provides the closest electrical substitution for the MMBT4400. All variants share identical maximum ratings: 45 V breakdown voltage, 500 mA collector current, and 300 mW power dissipation. These parts are active products with ROHS3 compliance and unlimited moisture sensitivity level. Selection among BC817 variants depends on required DC current gain (hFE) specification: BC817-16 series offers minimum hFE of 100, BC817-25 series offers minimum hFE of 160, and BC817-40 series offers minimum hFE of 250. Packaging variants (LT1G for Cut Tape & Digi-Reel, LT3G for Tape & Reel) are available based on procurement requirements.

For Applications Requiring 100 mA or Less Collector Current:

The BC847 series (BC847ALT1G, BC847BLT1G, BC847BLT3G, BC847CLT1G) is suitable only when maximum collector current does not exceed 100 mA. These parts offer 45 V breakdown voltage and 300 mW power dissipation with active product status and ROHS3 compliance. DC current gain varies by variant: BC847A offers minimum hFE of 110, BC847B offers minimum hFE of 200, and BC847C offers minimum hFE of 420.

Compliance and Availability:

All substitute parts are manufactured by onsemi with active product status, ensuring long-term availability and supply chain continuity. All parts carry ROHS3 compliance and REACH Unaffected status, matching the regulatory requirements of the obsolete MMBT4400.

Frequently Asked Questions (FAQ)

Q: Can BC817 series transistors directly replace MMBT4400 in all applications?

A: BC817 series transistors are electrically compatible with MMBT4400 in applications where collector current does not exceed 500 mA. The BC817 series provides higher breakdown voltage (45 V versus 40 V) and identical SOT-23-3 packaging. However, maximum power dissipation is reduced from 350 mW to 300 mW. Applications operating at the upper limits of MMBT4400 specifications require circuit analysis to confirm BC817 suitability.

Q: What is the difference between BC817-16, BC817-25, and BC817-40 variants?

A: The numeric suffix indicates the minimum DC current gain (hFE) specification. BC817-16 specifies minimum hFE of 100 at 100 mA collector current and 1 V collector-emitter voltage. BC817-25 specifies minimum hFE of 160 under identical conditions. BC817-40 specifies minimum hFE of 250. All other electrical parameters are identical across variants. Selection depends on circuit requirements for current gain.

Q: Are BC847 series transistors suitable as MMBT4400 replacements?

A: BC847 series transistors are suitable only for applications where maximum collector current does not exceed 100 mA. The MMBT4400 is rated for 600 mA maximum collector current, while BC847 series is rated for only 100 mA. Using BC847 in circuits designed for higher collector currents results in device failure or degraded performance.

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

A: Cut Tape & Digi-Reel packaging (LT1G suffix) is supplied on cut tape with reel options for automated handling. Tape & Reel packaging (LT3G suffix) is supplied on continuous tape on reel for high-volume automated assembly. Both packaging formats contain identical components; selection depends on manufacturing process requirements and procurement volume.

Q: Does the higher breakdown voltage of BC817 (45 V versus 40 V) affect circuit operation?

A: Higher breakdown voltage provides additional safety margin and does not negatively affect circuit operation. The BC817 breakdown voltage of 45 V exceeds the MMBT4400 specification of 40 V, making it suitable for applications designed for 40 V operation. No circuit modifications are required.

Q: Are all substitute parts RoHS3 compliant?

A: All BC817 and BC847 series substitute parts listed are ROHS3 compliant. The obsolete MMBT4400 does not carry RoHS3 compliance information. Substitution with active BC817 or BC847 parts ensures compliance with current environmental regulations.

Q: What is the operating temperature range difference between MMBT4400 and substitute parts?

A: MMBT4400 operates from -55°C to 150°C. BC817 series operates from -65°C to 150°C, providing extended low-temperature capability. BC847 series operates from -55°C to 150°C, matching the MMBT4400 range. Extended temperature range of BC817 series provides additional design flexibility without circuit modification.

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