ZTX855STOA Equivalent & Substitute Parts

Part Overview

The ZTX855STOA is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 4 A, collector-emitter breakdown voltage of 150 V, and maximum power dissipation of 1.2 W in a Through Hole E-Line (TO-92 compatible) package.

The ZTX855STOA is classified as an obsolete product. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure component availability, and support ongoing production and repair requirements for systems utilizing this transistor.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	4	A
Voltage - Collector Emitter Breakdown (Max)	150	V
Vce Saturation (Max) @ Ib, Ic	260 mV @ 400 mA, 4 A	—
Current - Collector Cutoff (Max)	50	nA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 1 A, 5 V	—
Power - Max	1.2	W
Frequency - Transition	90	MHz
Operating Temperature	-55 to 200	°C
Mounting Type	Through Hole	—
Package / Case	E-Line-3	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the ZTX855STOA are determined by electrical and mechanical parameter equivalence. All substitute parts must satisfy the following criteria:

Electrical Parameters (Must Match):

Transistor Type: NPN
Current - Collector (Ic) (Max): 4 A
Voltage - Collector Emitter Breakdown (Max): 150 V
Vce Saturation (Max) @ Ib, Ic: 260 mV @ 400 mA, 4 A
Current - Collector Cutoff (Max): 50 nA (ICBO)
DC Current Gain (hFE) (Min) @ Ic, Vce: 100 @ 1 A, 5 V
Power - Max: 1.2 W
Frequency - Transition: 90 MHz
Operating Temperature: -55°C to 200°C

Mechanical Parameters (Must Match):

Mounting Type: Through Hole
Package / Case: E-Line-3
Supplier Device Package: E-Line (TO-92 compatible)

Compliance Parameters (Must Match):

RoHS Status: ROHS3 Compliant
Moisture Sensitivity Level (MSL): 1 (Unlimited)

The substitute parts ZTX855 and ZTX855STZ are direct electrical equivalents of the ZTX855STOA. Both parts share identical electrical specifications and mechanical packaging. The primary differences are product status and packaging format.

Parameter Comparison

Parameter	ZTX855STOA	ZTX855	ZTX855STZ
Manufacturer	Diodes Incorporated	Diodes Incorporated	Diodes Incorporated
Transistor Type	NPN	NPN	NPN
Current - Collector (Ic) (Max)	4 A	4 A	4 A
Voltage - Collector Emitter Breakdown (Max)	150 V	150 V	150 V
Vce Saturation (Max) @ Ib, Ic	260 mV @ 400 mA, 4 A	260 mV @ 400 mA, 4 A	260 mV @ 400 mA, 4 A
Current - Collector Cutoff (Max)	50 nA	50 nA	50 nA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 1 A, 5 V	100 @ 1 A, 5 V	100 @ 1 A, 5 V
Power - Max	1.2 W	1.2 W	1.2 W
Frequency - Transition	90 MHz	90 MHz	90 MHz
Operating Temperature	-55 to 200 °C	-55 to 200 °C	-55 to 200 °C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	E-Line-3	E-Line-3	E-Line-3
Supplier Device Package	E-Line (TO-92 compatible)	E-Line (TO-92 compatible)	E-Line (TO-92 compatible)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)
Product Status	Obsolete	Active	Active
Packaging Format	Tube	Bulk	Tape & Box (TB)

Engineering Selection Recommendations

The ZTX855STOA is an obsolete product. For new designs and ongoing production requirements, selection between the active substitute parts should be based on packaging and supply considerations:

ZTX855 (Bulk Packaging): This part is the base product number in bulk packaging format. It is suitable for applications where individual component handling and custom packaging are acceptable. Current inventory availability is 4150 pieces.

ZTX855STZ (Tape & Box Packaging): This part is supplied in industry-standard Tape & Box format, optimized for automated assembly and high-volume production environments. Current inventory availability is 111900 pieces, indicating superior long-term availability.

Both substitute parts maintain full electrical and mechanical equivalence to the ZTX855STOA and carry identical ROHS3 compliance and MSL ratings. Selection between these two active alternatives should be determined by assembly process requirements and supply chain strategy rather than technical performance criteria.

Frequently Asked Questions (FAQ)

Q: Can ZTX855 and ZTX855STZ be used interchangeably with ZTX855STOA in existing designs?

A: Yes. Both substitute parts are electrically and mechanically identical to the ZTX855STOA. All three parts share the same NPN transistor type, 4 A maximum collector current, 150 V breakdown voltage, 1.2 W power rating, 90 MHz transition frequency, and E-Line (TO-92 compatible) Through Hole package. The differences are limited to product status and packaging format.

Q: What is the difference between ZTX855 and ZTX855STZ?

A: Both parts are electrically identical. The primary difference is packaging format. ZTX855 is supplied in bulk packaging, while ZTX855STZ is supplied in Tape & Box (TB) format. ZTX855STZ is optimized for automated assembly processes and high-volume production. ZTX855 is suitable for manual assembly or custom packaging requirements.

Q: Why is ZTX855STOA listed as obsolete?

A: The ZTX855STOA is classified as obsolete by the manufacturer. However, the base product ZTX855 and its variant ZTX855STZ remain active products with full manufacturer support and availability.

Q: Are there any compliance differences between the three parts?

A: No. All three parts—ZTX855STOA, ZTX855, and ZTX855STZ—are ROHS3 compliant, carry MSL rating of 1 (Unlimited), and are REACH unaffected. Compliance certifications are identical across all variants.

Q: Which substitute part should be selected for new production?

A: For new production, ZTX855STZ is recommended due to its Tape & Box packaging format, which is standard for automated assembly environments, and its significantly higher inventory availability (111900 pieces). ZTX855 in bulk packaging is an alternative if custom packaging or manual assembly processes are employed.

Q: Is the E-Line (TO-92 compatible) package the same across all three parts?

A: Yes. All three parts use the identical E-Line-3 package in E-Line (TO-92 compatible) Through Hole configuration. Pin assignments, lead spacing, and mechanical dimensions are identical, ensuring direct board-level compatibility.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message