KSE803S Equivalent & Substitute Parts

Part Overview

The KSE803S is an NPN Darlington bipolar junction transistor manufactured by onsemi, rated for 80 V collector-emitter breakdown voltage and 4 A maximum collector current in a TO-126-3 through-hole package. This component is classified as obsolete, necessitating identification of active equivalent parts for ongoing design requirements and production continuity. Substitute parts must maintain electrical performance within the specified parameter ranges while accommodating available packaging and supplier options.

Substiute Parts

KSE803S

onsemiIn Stock: 786KSE803S Datasheet

Current PartRFQ

BD679AS

onsemiIn Stock: 1998BD679AS Datasheet

DirectRFQ

BD679A

STMicroelectronicsIn Stock: 1566BD679A Datasheet

DirectRFQ

BD679

STMicroelectronicsIn Stock: 23392BD679 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the KSE803S is determined by strict equivalence across the following critical parameters: transistor type (NPN - Darlington), maximum collector current (4 A), collector-emitter breakdown voltage (80 V), maximum power dissipation (40 W), and operating temperature rating (150°C TJ). All substitute parts must maintain these electrical specifications to ensure functional compatibility within the original circuit design.

The substitute parts identified—BD679AS, BD679A, and BD679—are classified as direct or similar equivalents based on matching these core electrical parameters. Packaging variations exist between the main part (TO-126-3) and certain substitutes (SOT-32-3), which affects physical board layout but does not alter electrical performance when pin assignments are preserved. Manufacturer differences (onsemi versus STMicroelectronics) and product status variations (obsolete versus active) are noted to support procurement decisions.

Parameter Comparison

Engineering Selection Recommendations

BD679AS (onsemi) is the primary direct substitute for the KSE803S. This part maintains identical electrical specifications, operates at active product status, and is supplied in the original TO-126-3 package format. BD679AS carries ROHS3 compliance certification, supporting modern manufacturing and environmental standards. Inventory availability (1956 pcs) ensures procurement reliability.

BD679A (STMicroelectronics) provides electrical equivalence with identical core parameters but differs in package format (SOT-32-3 instead of TO-126-3). This substitution requires physical board layout modification to accommodate the alternative through-hole package. ROHS3 compliance and active product status support long-term availability. Inventory (1475 pcs) is adequate for production requirements.

BD679 (STMicroelectronics) operates as a similar equivalent with minor variations in saturation voltage specifications (2.5V @ 30mA, 1.5A versus 2.8V @ 40mA, 2A) and current gain measurement conditions (750 @ 1.5A, 3V versus 750 @ 2A, 3V). This part is supplied in SOT-32-3 package and requires board layout revision. Highest inventory availability (23300 pcs) supports high-volume production. ROHS3 compliance and active status confirm regulatory alignment.

All substitute parts maintain the 80 V breakdown voltage, 4 A maximum collector current, 40 W power rating, and 150°C operating temperature required for functional equivalence. Selection between BD679AS, BD679A, and BD679 depends on packaging constraints, manufacturer preference, and inventory requirements rather than electrical performance.

Frequently Asked Questions (FAQ)

Q: Can the BD679AS directly replace the KSE803S without circuit modification?

A: Yes. The BD679AS maintains identical electrical specifications and is supplied in the same TO-126-3 package. No circuit or board layout changes are required for direct substitution.

Q: What is the primary difference between BD679AS and BD679A?

A: The BD679AS is supplied in TO-126-3 package (matching the original KSE803S), while BD679A uses SOT-32-3 package. Both are manufactured by different suppliers (onsemi versus STMicroelectronics) and maintain equivalent electrical performance. Package selection determines board layout compatibility.

Q: Are there electrical differences between BD679A and BD679?

A: Both parts are NPN Darlington transistors with 80 V breakdown voltage and 4 A maximum collector current. Minor variations exist in saturation voltage test conditions and current gain measurement points. These differences do not affect functional equivalence in typical circuit applications operating within the specified parameter ranges.

Q: Does the KSE803S obsolescence affect the availability of substitute parts?

A: No. All identified substitutes (BD679AS, BD679A, BD679) maintain active product status with confirmed inventory availability. BD679 shows the highest stock level (23300 pcs), ensuring long-term procurement continuity.

Q: Are all substitute parts RoHS compliant?

A: BD679AS, BD679A, and BD679 are all ROHS3 compliant. The original KSE803S does not specify RoHS status. Compliance certification for substitute parts supports modern manufacturing and environmental regulatory requirements.

Q: What packaging considerations apply when selecting between substitute options?

A: BD679AS maintains the original TO-126-3 through-hole package, requiring no board layout changes. BD679A and BD679 use SOT-32-3 package, which is also through-hole but with different pin spacing and physical dimensions. Board layout modification is necessary when switching to SOT-32-3 packages.

Q: Can I use BD679 instead of BD679A in the same application?

A: Yes. Both parts are electrically equivalent NPN Darlington transistors with matching voltage and current ratings. The choice between them depends on manufacturer preference, inventory availability, and package compatibility with your board design.