2N5550G Equivalent & Substitute Parts

Part Overview

The 2N5550G is an NPN bipolar junction transistor manufactured by onsemi, rated for 140 V collector-emitter breakdown voltage and 600 mA maximum collector current. This device is packaged in a through-hole TO-92 (TO-226-3) configuration and is designed for general-purpose switching and amplification applications. The 2N5550G is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity. Substitute parts must maintain electrical compatibility across critical parameters including voltage rating, current capacity, and thermal operating range while accommodating different packaging technologies.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	140	V
Current - Collector (Ic) (Max)	600	mA
Power - Max	625	mW
DC Current Gain (hFE) (Min) @ Ic, Vce	60 @ 10mA, 5V	—
Vce Saturation (Max) @ Ib, Ic	250mV @ 5mA, 50mA	—
Frequency - Transition	300	MHz
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226-3)	—

Substitute Part Grouping Explanation

Substitution of the 2N5550G is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Electrical Compatibility Requirements:

Voltage - Collector Emitter Breakdown (Max) must equal or exceed 140 V
Current - Collector (Ic) (Max) must equal or exceed 600 mA
DC Current Gain (hFE) must support the intended bias conditions
Vce Saturation characteristics must be compatible with circuit switching requirements
Operating temperature range must encompass -55°C to 150°C minimum

Mechanical Compatibility Requirements:

Transistor type must be NPN
Package form factor must be compatible with board layout and thermal requirements
Mounting technology (through-hole or surface-mount) determines PCB integration method

The 2N5550G has two identified substitute parts: MMBT5550LT1G (onsemi, surface-mount SOT-23-3) and ZTX455 (Diodes Incorporated, through-hole E-Line). Both maintain the 140 V voltage rating and 600 mA minimum current capacity. The MMBT5550LT1G provides electrical equivalence with surface-mount packaging, while the ZTX455 offers enhanced current capacity (1 A) and power rating (1 W) in a through-hole compatible form factor.

Parameter Comparison

Parameter	2N5550G	MMBT5550LT1G	ZTX455
Manufacturer	onsemi	onsemi	Diodes Incorporated
Transistor Type	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	140 V	140 V	140 V
Current - Collector (Ic) (Max)	600 mA	600 mA	1 A
Power - Max	625 mW	225 mW	1 W
DC Current Gain (hFE) (Min) @ Ic, Vce	60 @ 10mA, 5V	60 @ 10mA, 5V	100 @ 150mA, 10V
Vce Saturation (Max) @ Ib, Ic	250mV @ 5mA, 50mA	250mV @ 5mA, 50mA	700mV @ 15mA, 150mA
Frequency - Transition	300 MHz	—	100 MHz
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 200°C
Mounting Type	Through Hole	Surface Mount	Through Hole
Package / Case	TO-92-3 (TO-226-3)	SOT-23-3 (TO-236)	E-Line-3 (TO-92 compatible)
Product Status	Obsolete	Active	Active
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

MMBT5550LT1G Selection Criteria: The MMBT5550LT1G is an active product from onsemi with ROHS3 compliance. This substitute maintains identical electrical specifications to the 2N5550G (140 V, 600 mA, 60 hFE @ 10mA/5V, 250mV Vce saturation). The primary distinction is packaging: SOT-23-3 surface-mount versus TO-92 through-hole. The MMBT5550LT1G is suitable for new designs or board redesigns that accommodate surface-mount technology. Power dissipation is reduced to 225 mW, which may require thermal evaluation in high-power applications. This part is recommended when PCB layout permits surface-mount integration and when the 2N5550G through-hole footprint is not a constraint.

ZTX455 Selection Criteria: The ZTX455 is an active product from Diodes Incorporated with ROHS3 compliance and extended operating temperature range (-55 to 200°C). This substitute maintains the 140 V voltage rating and exceeds the 600 mA current requirement with a 1 A maximum rating. The ZTX455 offers higher power dissipation (1 W) and improved current gain (100 hFE @ 150mA/10V). The E-Line package is through-hole compatible with TO-92 footprints. Vce saturation is higher (700mV @ 15mA/150mA) compared to the 2N5550G (250mV @ 5mA/50mA), which may affect switching performance in saturation-mode applications. The ZTX455 is recommended for through-hole designs requiring higher current capacity or extended temperature operation.

Both substitute parts are active products with current manufacturing support and regulatory compliance, providing long-term design continuity beyond the obsolete 2N5550G.

Frequently Asked Questions (FAQ)

Q: Can the MMBT5550LT1G directly replace the 2N5550G in an existing through-hole design?

A: No. The MMBT5550LT1G uses SOT-23-3 surface-mount packaging, while the 2N5550G uses TO-92 through-hole packaging. PCB layout and assembly process modifications are required. Pin configuration differs between packages. If through-hole mounting is mandatory, the ZTX455 is the appropriate substitute.

Q: What is the primary electrical difference between the 2N5550G and ZTX455?

A: Both devices maintain the 140 V voltage rating and support 600 mA minimum collector current. The ZTX455 provides higher maximum current (1 A) and power dissipation (1 W). Vce saturation differs: 2N5550G is 250mV @ 5mA/50mA, while ZTX455 is 700mV @ 15mA/150mA. This saturation difference affects switching speed and power loss in saturation-mode circuits.

Q: Is the MMBT5550LT1G electrically equivalent to the 2N5550G?

A: Yes, for the specified electrical parameters. Both devices have 140 V breakdown voltage, 600 mA maximum collector current, 60 hFE @ 10mA/5V, and 250mV Vce saturation @ 5mA/50mA. The MMBT5550LT1G operates over the same temperature range (-55 to 150°C). Transition frequency is not specified for the MMBT5550LT1G, so high-frequency performance comparison is not available from provided data.

Q: Can the ZTX455 be used in applications requiring 300 MHz transition frequency?

A: The ZTX455 has a transition frequency of 100 MHz, which is lower than the 2N5550G specification of 300 MHz. Applications requiring 300 MHz operation must evaluate whether 100 MHz is sufficient for the intended circuit function. High-frequency switching applications may experience performance degradation.

Q: What are the compliance and availability advantages of the substitute parts?

A: Both MMBT5550LT1G and ZTX455 are active products with current manufacturing support. Both are ROHS3 compliant, addressing regulatory requirements. The 2N5550G is obsolete, creating supply chain risk. The MMBT5550LT1G has 605,400 units in stock, and the ZTX455 has 1,583 units in stock, providing immediate availability for production.

Q: Which substitute is recommended for a new design?

A: Selection depends on packaging requirements. For surface-mount designs, the MMBT5550LT1G provides direct electrical equivalence with active product status. For through-hole designs, the ZTX455 offers enhanced current and power ratings with through-hole compatibility. Both are active products with long-term support.

Q: Are there thermal considerations when substituting the 2N5550G?

A: The MMBT5550LT1G has reduced power dissipation (225 mW vs. 625 mW), which may improve thermal performance in power-limited applications but may require verification in high-power circuits. The ZTX455 has higher power dissipation (1 W), providing better thermal margin. The ZTX455 also supports extended temperature operation (-55 to 200°C vs. -55 to 150°C), offering wider thermal operating range.

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