ZTX449 Equivalent & Substitute Parts

Part Overview

The ZTX449 is a Bipolar (BJT) NPN transistor manufactured by Diodes Incorporated, rated for 30V collector-emitter breakdown voltage and 1A maximum collector current. This component is designed for through-hole mounting in the E-Line (TO-92 compatible) package format. The ZTX449 is classified as obsolete, necessitating identification of equivalent substitute parts for ongoing design requirements and production continuity. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Substiute Parts

ZTX449

Diodes IncorporatedIn Stock: 25474ZTX449 Datasheet

Current PartRFQ

KSD471ACYBU

onsemiIn Stock: 10776KSD471ACYBU Datasheet

MFR RecommendedRFQ

PN2222ABU

onsemiIn Stock: 2929PN2222ABU Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the ZTX449 are selected based on the following critical parameters that determine functional equivalence:

Primary Compatibility Criteria:

• Transistor Type: NPN (must match)
• Current - Collector (Ic) Max: 1 A (must equal or exceed)
• Voltage - Collector Emitter Breakdown: 30 V minimum (must equal or exceed)
• Mounting Type: Through Hole (must match)
• Package Format: TO-92 compatible pinout (must match)

Secondary Considerations:

• Power dissipation capability
• Frequency response characteristics
• Operating temperature range
• RoHS and REACH compliance status

The identified substitute parts KSD471ACYBU and PN2222ABU meet the primary compatibility criteria. Both are NPN transistors with 1A collector current rating, through-hole mounting, and TO-92-3 package compatibility. Both maintain ROHS3 compliance and REACH unaffected status.

Parameter Comparison

Engineering Selection Recommendations

KSD471ACYBU (onsemi): This substitute maintains electrical equivalence with the ZTX449 across primary parameters: 1A collector current, 30V breakdown voltage, and through-hole TO-92-3 package. The KSD471ACYBU exhibits lower saturation voltage (500mV vs. 1V) and higher DC current gain (120 vs. 100), providing improved switching characteristics. Power dissipation is reduced to 800mW compared to the original 1W specification. The product status is Last Time Buy, indicating limited future availability. ROHS3 compliance and REACH unaffected status are maintained. Operating temperature maximum is 150°C, which is lower than the ZTX449 specification of 200°C.

PN2222ABU (onsemi): This substitute exceeds the primary electrical requirements with a 40V breakdown voltage rating (vs. 30V required) and maintains 1A collector current and through-hole TO-92-3 package compatibility. The PN2222ABU offers superior frequency response at 300MHz (vs. 150MHz) and lower collector cutoff current (10nA vs. 100nA). Power dissipation is 625mW. The product status is Active, ensuring ongoing availability. ROHS3 compliance and REACH unaffected status are maintained. Operating temperature range is -55°C to 150°C, matching the lower temperature limit of the ZTX449 but with a reduced maximum of 150°C.

Selection Basis:

• Both substitutes are ROHS3 compliant and REACH unaffected, meeting regulatory requirements
• Both maintain through-hole mounting and TO-92-3 package compatibility
• PN2222ABU is recommended for new designs requiring long-term component availability (Active status)
• KSD471ACYBU is suitable for applications where exact parameter matching is prioritized, with awareness of Last Time Buy status
• Applications requiring operation above 150°C require design review, as both substitutes have reduced maximum operating temperature compared to ZTX449

Frequently Asked Questions (FAQ)

Q: Can KSD471ACYBU and PN2222ABU be used interchangeably with ZTX449?

A: Both parts are functionally equivalent for applications within their specified parameter ranges. They share identical collector current (1A) and through-hole TO-92-3 package compatibility. However, differences in power dissipation, frequency response, and maximum operating temperature must be evaluated against specific circuit requirements.

Q: What is the primary difference between KSD471ACYBU and PN2222ABU?

A: The PN2222ABU has a higher breakdown voltage rating (40V vs. 30V) and superior frequency response (300MHz vs. 130MHz). The KSD471ACYBU provides lower saturation voltage and higher DC current gain. PN2222ABU has Active product status, while KSD471ACYBU is Last Time Buy.

Q: Are the packages physically identical?

A: Both substitute parts use TO-92-3 (TO-226AA) package format, which is compatible with the ZTX449 E-Line-3 (TO-92 compatible) package. Physical pinout and lead spacing are compatible for through-hole mounting applications.

Q: What is the impact of reduced power dissipation in substitute parts?

A: KSD471ACYBU is rated at 800mW and PN2222ABU at 625mW, compared to ZTX449 at 1W. Applications requiring continuous operation at maximum collector current and voltage must ensure thermal design accommodates the reduced power budget of substitute parts.

Q: Are there temperature limitations when substituting?

A: Both substitute parts have maximum operating temperature of 150°C, compared to ZTX449 at 200°C. Applications requiring operation above 150°C require alternative component selection or circuit redesign.

Q: Do the substitutes maintain compliance certifications?

A: Yes. Both KSD471ACYBU and PN2222ABU are ROHS3 compliant and REACH unaffected, matching the ZTX449 compliance status.

Q: Which substitute is recommended for new production designs?

A: PN2222ABU is recommended for new designs due to Active product status, ensuring long-term availability. KSD471ACYBU is suitable for legacy system support with awareness of Last Time Buy status.