ZTX857STZ Equivalent & Substitute Parts

Part Overview

The ZTX857STZ is an NPN bipolar junction transistor manufactured by Diodes Incorporated, designed for high-voltage switching and amplification applications. This device operates at collector-emitter breakdown voltages up to 300 V with a maximum collector current of 3 A and power dissipation of 1.2 W. The transistor is packaged in an E-Line (TO-92 compatible) configuration with formed leads suitable for through-hole mounting. The ZTX857STZ is classified as an active product with full RoHS3 compliance and unlimited moisture sensitivity rating. Substitute parts are identified when electrical characteristics, mechanical packaging, and operational parameters align within specified tolerances, enabling direct replacement in circuit designs without functional degradation.

Substiute Parts

ZTX857STZ

Diodes IncorporatedIn Stock: 1137ZTX857STZ Datasheet

Current PartRFQ

ZTX857

Diodes IncorporatedIn Stock: 6240ZTX857 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the ZTX857STZ is determined by strict equivalence across the following critical parameters:

Electrical Characteristics: Collector current rating (3 A maximum), collector-emitter breakdown voltage (300 V maximum), power dissipation capability (1.2 W), transition frequency (80 MHz), and DC current gain (100 minimum at specified conditions) must be identical or superior.

Mechanical Compatibility: Package type must be E-Line (TO-92 compatible) with through-hole mounting configuration to ensure physical fit and lead compatibility in existing PCB designs.

Operational Range: Operating temperature range of -55°C to 200°C must be maintained.

Regulatory Compliance: RoHS3 compliance and REACH unaffected status must be preserved.

Transistor Polarity: NPN configuration is mandatory; no PNP substitutes are applicable.

The ZTX857STZ in Cut Tape packaging is directly substitutable with the ZTX857 in Bulk packaging, as both share identical electrical specifications and E-Line package geometry.

Parameter Comparison

Engineering Selection Recommendations

The ZTX857 (Bulk packaging) is a direct functional equivalent to the ZTX857STZ (Cut Tape packaging). Both parts are manufactured by Diodes Incorporated and maintain active product status with full regulatory compliance. The electrical performance parameters are identical across all critical specifications including voltage, current, power, and frequency ratings. The substitute part exhibits superior collector cutoff current characteristics (50 nA versus 1 µA), representing an improvement in leakage performance.

Selection between these parts is determined by packaging and supply requirements rather than electrical performance. The ZTX857STZ in Cut Tape format is suitable for automated assembly processes requiring pre-formed tape reels. The ZTX857 in Bulk packaging accommodates manual assembly, kit builds, or applications where tape packaging is not required. Both parts satisfy identical circuit design requirements and thermal management specifications.

Frequently Asked Questions (FAQ)

Q: Can the ZTX857 (Bulk) directly replace the ZTX857STZ (Cut Tape) in production assembly?

A: Yes. Both parts are electrically identical with matching electrical specifications, package geometry, and pin configuration. The difference is packaging format only. Cut Tape packaging is optimized for automated pick-and-place equipment, while Bulk packaging is suitable for manual assembly or alternative handling methods. Circuit performance is unaffected by this substitution.

Q: Are there any thermal or power handling differences between these parts?

A: No. Both the ZTX857STZ and ZTX857 are rated for identical maximum power dissipation of 1.2 W and operate across the same temperature range of -55°C to 200°C. Thermal management requirements and heat sink considerations remain unchanged.

Q: Does the ZTX857 substitute have better leakage characteristics?

A: The ZTX857 in Bulk packaging specifies a maximum collector cutoff current (ICBO) of 50 nanoamperes, compared to 1 microampere for the ZTX857STZ. This represents superior leakage performance in the substitute part, which may provide marginal benefits in low-power or precision applications, though both values are within acceptable ranges for standard switching applications.

Q: Are both parts RoHS3 compliant?

A: Yes. Both the ZTX857STZ and ZTX857 carry full RoHS3 compliance certification and REACH unaffected status, meeting all current environmental and regulatory requirements for commercial and industrial applications.

Q: What is the physical package compatibility between these parts?

A: Both parts use the E-Line (TO-92 compatible) package with through-hole mounting. The physical lead configuration, spacing, and PCB footprint are identical, ensuring direct mechanical compatibility without PCB redesign or rework.

Q: Can these parts be used interchangeably in high-frequency switching applications?

A: Yes. Both parts maintain an 80 MHz transition frequency specification, supporting identical switching speed performance in high-frequency circuit designs. No frequency-dependent circuit modifications are required when substituting between these parts.