KSE701STU Equivalent & Substitute Parts

Part Overview

The KSE701STU is a PNP Darlington bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 4 A maximum collector current in a TO-126-3 through-hole package. This device is classified as obsolete, necessitating identification of active equivalent components for new designs and ongoing production requirements. Substitute parts must maintain electrical performance within the specified parameter ranges while accommodating packaging and compliance differences.

Substiute Parts

KSE701STU

onsemiIn Stock: 2250KSE701STU Datasheet

Current PartRFQ

BD678

STMicroelectronicsIn Stock: 1259BD678 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the KSE701STU is determined by strict equivalence across the following electrical and mechanical parameters:

Critical Matching Parameters:

• Transistor topology: PNP Darlington configuration
• Maximum collector current: 4 A
• Maximum collector-emitter breakdown voltage: 60 V
• Maximum power dissipation: 40 W
• Operating temperature range: 150°C (TJ)
• Mounting classification: Through Hole
• Minimum DC current gain (hFE): 750 @ specified Ic and Vce conditions

Package Compatibility: Substitute parts must be compatible with through-hole mounting applications. Physical package differences (TO-126-3 versus SOT-32-3) are acceptable provided the electrical specifications remain within tolerance and the device footprint accommodates the application circuit board layout.

The BD678 manufactured by STMicroelectronics meets all critical electrical parameters and maintains through-hole mounting compatibility, qualifying it as a direct functional equivalent despite packaging designation differences.

Parameter Comparison

Engineering Selection Recommendations

Primary Selection: BD678 (STMicroelectronics)

The BD678 is the qualified substitute for the obsolete KSE701STU. Selection rationale is based on the following factors:

Electrical Equivalence: The BD678 maintains all critical electrical specifications within the KSE701STU parameter envelope. Maximum collector current (4 A), collector-emitter breakdown voltage (60 V), power dissipation (40 W), and operating temperature (150°C) are identical. DC current gain minimum specification (750) is matched. Vce saturation and collector cutoff current specifications show minor variations within acceptable engineering tolerances for Darlington transistor applications.

Product Status and Compliance: The BD678 carries Active product status, ensuring continued availability and manufacturing support. The device is RoHS3 Compliant and REACH Unaffected, meeting current regulatory requirements. Both REACH and ECCN classifications are equivalent to the original part.

Packaging and Mounting: Both devices are through-hole mounted components. The BD678 is supplied in SOT-32-3 packaging versus the KSE701STU TO-126-3 designation. Through-hole mounting compatibility is maintained, though circuit board layout verification is required to confirm physical footprint accommodation.

Inventory and Supply: The BD678 is available in active production with 1245 units in stock, providing supply continuity for the obsolete KSE701STU.

Frequently Asked Questions (FAQ)

Q: Can the BD678 be used as a direct replacement for the KSE701STU in existing designs?

A: The BD678 is electrically equivalent across all critical parameters (collector current, breakdown voltage, power rating, and current gain). Through-hole mounting is maintained. Physical package differences (SOT-32-3 versus TO-126-3) require verification that the circuit board footprint accommodates the substitute device. No circuit redesign is necessary if physical mounting can be accommodated.

Q: What are the key differences between the KSE701STU and BD678?

A: The primary differences are product status (obsolete versus active), manufacturer (onsemi versus STMicroelectronics), and supplier device package designation (TO-126-3 versus SOT-32-3). Electrical specifications are equivalent. Collector cutoff current is higher in the BD678 (500µA versus 100µA), and Vce saturation is measured at slightly different base current and collector current conditions, but both remain within acceptable operating ranges for Darlington applications.

Q: Are there any compliance or certification differences between these parts?

A: The BD678 is RoHS3 Compliant, while the KSE701STU compliance status is not specified in the provided data. Both devices are REACH Unaffected and carry identical ECCN (EAR99) and HTSUS classifications. Moisture sensitivity level is equivalent (MSL 1 - Unlimited) for both parts.

Q: What should be verified before implementing the BD678 as a substitute?

A: Circuit board layout must accommodate the SOT-32-3 package footprint. Electrical performance under the specific application's operating conditions (collector current, base current, and temperature) should be confirmed within the BD678 parameter specifications. Physical mounting clearance and thermal management provisions should be assessed if the original design utilized specific TO-126-3 package characteristics.

Q: Is the BD678 available in the same packaging as the KSE701STU?

A: No. The BD678 is supplied in SOT-32-3 packaging, while the KSE701STU uses TO-126-3. Both are through-hole mounted, but the physical dimensions and pin spacing differ. PCB layout modification may be required.

Q: What is the minimum DC current gain for both devices?

A: Both the KSE701STU and BD678 specify a minimum DC current gain (hFE) of 750. The KSE701STU measurement is taken at 2 A collector current and 3 V Vce, while the BD678 measurement is at 1.5 A collector current and 3 V Vce. Both values meet the 750 minimum specification.