MPS918 Equivalent & Substitute Parts

Part Overview

The MPS918 is an NPN bipolar junction transistor (BJT) manufactured by onsemi, designed for general-purpose switching and amplification applications. The device is rated for 15 V collector-emitter breakdown voltage with a maximum collector current of 50 mA and operates across a temperature range of -55°C to 150°C. The MPS918 is packaged in a through-hole TO-92 (TO-226-3) configuration with a maximum power dissipation of 350 mW and a transition frequency of 600 MHz.

The MPS918 is classified as obsolete. Locating equivalent substitute parts is necessary to support ongoing maintenance, repair, and redesign requirements for legacy systems and applications currently utilizing this component.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	15	V
Current - Collector (Ic) (Max)	50	mA
Vce Saturation (Max) @ Ib, Ic	400 mV @ 1 mA, 10 mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	20 @ 3 mA, 10 V	—
Power - Max	350	mW
Frequency - Transition	600	MHz
Operating Temperature	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-226-3, TO-92-3 Long Body	—

Substitute Part Grouping Explanation

Substitution of the MPS918 is determined by electrical and mechanical parameter compatibility within the NPN BJT category. The following parameters establish the substitution criteria:

Electrical Parameters (Required Match):

Transistor Type: NPN
Voltage - Collector Emitter Breakdown (Max): 15 V minimum
Current - Collector (Ic) (Max): 50 mA minimum
DC Current Gain (hFE) (Min) @ Ic, Vce: 20 or greater
Frequency - Transition: 600 MHz minimum
Operating Temperature Range: -55°C to 150°C (TJ)

Mechanical Parameters:

Package compatibility: Through-hole or surface-mount variants of the same base device family

The MMBT918LT1G is a direct functional equivalent of the MPS918, sharing the same base product number (MMBT918 vs. MPS918) and manufactured by the same supplier (onsemi). The primary distinction is the package format: the MMBT918LT1G uses a surface-mount SOT-23-3 (TO-236) package instead of the through-hole TO-92 configuration.

Parameter Comparison

Parameter	MPS918	MMBT918LT1G	Match Status
Transistor Type	NPN	NPN	Match
Voltage - Collector Emitter Breakdown (Max)	15 V	15 V	Match
Current - Collector (Ic) (Max)	50 mA	50 mA	Match
DC Current Gain (hFE) (Min) @ Ic, Vce	20 @ 3 mA, 10 V	20 @ 3 mA, 1 V	Compatible
Frequency - Transition	600 MHz	600 MHz	Match
Operating Temperature	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	Match
Power - Max	350 mW	225 mW	Substitute lower
Mounting Type	Through Hole	Surface Mount	Different
Package / Case	TO-226-3, TO-92-3	TO-236-3, SC-59, SOT-23-3	Different

Engineering Selection Recommendations

Product Status Consideration: The MPS918 is classified as obsolete, while the MMBT918LT1G is active and in production. The MMBT918LT1G maintains full electrical compatibility with the MPS918 across all critical parameters: NPN type, 15 V breakdown voltage, 50 mA maximum collector current, 600 MHz transition frequency, and identical operating temperature range.

Compliance and Certification: The MPS918 is RoHS non-compliant. The MMBT918LT1G is ROHS3 compliant. Both devices are REACH unaffected and classified under ECCN EAR99. The MMBT918LT1G is the preferred selection for new designs and applications requiring RoHS compliance.

Power Dissipation: The MMBT918LT1G has a maximum power rating of 225 mW compared to the MPS918's 350 mW. Applications requiring power dissipation above 225 mW must verify that the MMBT918LT1G operates within acceptable thermal limits for the specific circuit design.

Package Consideration: The MMBT918LT1G uses a surface-mount SOT-23-3 package, requiring PCB layout and assembly modifications from the through-hole TO-92 configuration of the MPS918. Circuit board redesign is necessary for direct substitution.

Frequently Asked Questions (FAQ)

Q: Can the MMBT918LT1G directly replace the MPS918 without circuit modification?

A: The MMBT918LT1G is electrically equivalent to the MPS918 across all critical parameters. However, package format differs: the MPS918 uses through-hole TO-92 mounting, while the MMBT918LT1G uses surface-mount SOT-23-3 mounting. PCB layout and assembly process modifications are required.

Q: What is the significance of the power rating difference between the MPS918 (350 mW) and MMBT918LT1G (225 mW)?

A: The lower power rating of the MMBT918LT1G reflects the thermal characteristics of the smaller SOT-23-3 package. Applications must verify that circuit operating conditions maintain power dissipation within 225 mW limits. Circuits designed for the full 350 mW capability of the MPS918 require thermal analysis before substitution.

Q: Are there differences in DC current gain specifications between these devices?

A: Both devices specify a minimum DC current gain (hFE) of 20. The MPS918 specifies this at 3 mA collector current and 10 V collector-emitter voltage, while the MMBT918LT1G specifies it at 3 mA collector current and 1 V collector-emitter voltage. Both meet the minimum gain requirement for equivalent circuit performance.

Q: What is the inventory status of these parts?

A: The MPS918 has 1,185 pieces in stock as new original inventory. The MMBT918LT1G has 60,200 pieces in stock as new original inventory. The MMBT918LT1G offers significantly higher availability for ongoing production and support requirements.

Q: Does the MMBT918LT1G meet RoHS compliance requirements?

A: Yes. The MMBT918LT1G is ROHS3 compliant. The MPS918 is RoHS non-compliant. Applications requiring RoHS compliance must use the MMBT918LT1G.

Q: Are the operating temperature ranges identical?

A: Yes. Both the MPS918 and MMBT918LT1G operate across the same temperature range of -55°C to 150°C (junction temperature). No thermal performance differences exist between the devices.

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