SS8550BBU Equivalent & Substitute Parts

Part Overview

The SS8550BBU is a PNP bipolar junction transistor manufactured by onsemi, rated for 25 V collector-emitter breakdown voltage and 1.5 A maximum collector current. This device is packaged in a TO-92-3 through-hole configuration and is designed for general-purpose switching and amplification applications requiring 1 W power dissipation capability.

The SS8550BBU is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this component.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) (Max)	1.5	A
Voltage - Collector Emitter Breakdown (Max)	25	V
Vce Saturation (Max) @ Ib, Ic	500mV @ 80mA, 800mA	—
Current - Collector Cutoff (Max)	100	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	85	@ 100mA, 1V
Power - Max	1	W
Frequency - Transition	200	MHz
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the SS8550BBU is determined by the following critical parameters:

Mandatory Matching Criteria:

Transistor Type: PNP
Voltage - Collector Emitter Breakdown (Max): 25 V minimum
Current - Collector (Ic) (Max): 1.5 A minimum
Mounting Type: Through Hole
Package Compatibility: TO-92-3 or TO-92 compatible form factor

Acceptable Variation Criteria:

DC Current Gain (hFE): May exceed minimum specification
Frequency - Transition: May be lower than 200 MHz
Maximum Collector Current: May exceed 1.5 A
Operating Temperature Range: May be wider than specified
Vce Saturation: Must not exceed specified values at rated conditions
Product Status: Active status preferred for ongoing availability

The identified substitute parts meet or exceed the mandatory matching criteria while maintaining electrical and mechanical compatibility with the original SS8550BBU design.

Parameter Comparison

Parameter	SS8550BBU	SS8550DTA	ZTX749
Manufacturer	onsemi	onsemi	Diodes Incorporated
Transistor Type	PNP	PNP	PNP
Current - Collector (Ic) (Max)	1.5 A	1.5 A	2 A
Voltage - Collector Emitter Breakdown (Max)	25 V	25 V	25 V
Vce Saturation (Max) @ Ib, Ic	500mV @ 80mA, 800mA	500mV @ 80mA, 800mA	500mV @ 200mA, 2A
Current - Collector Cutoff (Max)	100 nA	100 nA	100 nA
DC Current Gain (hFE) (Min) @ Ic, Vce	85 @ 100mA, 1V	160 @ 100mA, 1V	100 @ 1A, 2V
Power - Max	1 W	1 W	1 W
Frequency - Transition	200 MHz	200 MHz	160 MHz
Operating Temperature (TJ)	150°C	150°C	-55°C ~ 200°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	E-Line-3 (TO-92 compatible)
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

SS8550DTA (onsemi)

The SS8550DTA is the direct equivalent to the SS8550BBU, sharing identical electrical specifications and package configuration. This part is manufactured by the same supplier (onsemi) and maintains active product status, ensuring long-term availability. The SS8550DTA is supplied in cut tape packaging and is suitable for direct substitution in all applications currently using the SS8550BBU. Both parts are ROHS3 compliant and carry identical regulatory certifications.

ZTX749 (Diodes Incorporated)

The ZTX749 is a cross-manufacturer substitute manufactured by Diodes Incorporated. This device exceeds the SS8550BBU specifications in maximum collector current (2 A versus 1.5 A) and provides an extended operating temperature range (-55°C to 200°C versus 150°C maximum). The ZTX749 is packaged in an E-Line-3 form factor that is mechanically compatible with TO-92 configurations. This part is active and ROHS3 compliant. The ZTX749 operates at a lower transition frequency (160 MHz versus 200 MHz) but maintains all critical electrical parameters required for substitution. The higher current rating and extended temperature range provide additional design margin for applications requiring enhanced thermal or current performance.

Frequently Asked Questions (FAQ)

Q: Can the SS8550DTA be used as a direct replacement for the SS8550BBU?

A: Yes. The SS8550DTA is electrically and mechanically identical to the SS8550BBU. Both devices share the same collector current rating (1.5 A), breakdown voltage (25 V), saturation characteristics, and TO-92-3 package configuration. The primary difference is product status: SS8550DTA is active while SS8550BBU is obsolete.

Q: What are the key differences between the SS8550DTA and ZTX749?

A: The SS8550DTA and ZTX749 differ in maximum collector current (1.5 A versus 2 A), transition frequency (200 MHz versus 160 MHz), and operating temperature range (150°C maximum versus -55°C to 200°C). Both devices maintain the same 25 V breakdown voltage and 1 W power rating. The ZTX749 is manufactured by Diodes Incorporated and uses an E-Line-3 package, while the SS8550DTA is an onsemi product in TO-92-3 packaging.

Q: Are there packaging considerations when substituting the ZTX749 for the SS8550BBU?

A: The ZTX749 uses an E-Line-3 package form factor that is mechanically compatible with TO-92 configurations. Pin assignments and lead spacing are compatible with standard TO-92 through-hole PCB layouts. Physical dimensions may vary slightly, but the device is suitable for direct PCB mounting in applications designed for TO-92-3 components.

Q: Do all substitute parts meet the same compliance requirements as the SS8550BBU?

A: Yes. Both the SS8550DTA and ZTX749 are ROHS3 compliant and carry REACH Unaffected status, matching the regulatory certifications of the SS8550BBU. All three parts are classified under ECCN EAR99 and share the same HTSUS code (8541.29.0075).

Q: Which substitute part should be selected for applications requiring maximum current capacity?

A: The ZTX749 is rated for 2 A maximum collector current, exceeding the 1.5 A rating of the SS8550BBU. This device is suitable for applications requiring higher current handling capability. The SS8550DTA maintains the original 1.5 A specification and is appropriate for applications with current requirements at or below this level.

Q: Can the SS8550BBU be used interchangeably with either substitute in all circuit configurations?

A: The SS8550DTA is a direct equivalent and can be used interchangeably in all applications. The ZTX749 can be substituted in applications where the 1.5 A current requirement is not exceeded and where the 160 MHz transition frequency is acceptable. Circuit designs that depend on the 200 MHz frequency specification should use either the SS8550BBU or SS8550DTA.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message