KSE702S Equivalent & Substitute Parts

Part Overview

The KSE702S is a PNP 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 equivalent substitute parts for ongoing design support and procurement continuity. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP - Darlington	—
Current - Collector (Ic) (Max)	4	A
Voltage - Collector Emitter Breakdown (Max)	80	V
Power - Max	40	W
DC Current Gain (hFE) (Min)	750	—
Mounting Type	Through Hole	—
Operating Temperature (Max)	150	°C (TJ)

Substitute Part Grouping Explanation

Substitute parts for the KSE702S are qualified based on the following electrical and mechanical parameters:

Electrical Compatibility Criteria:

Transistor type: PNP - Darlington configuration
Maximum collector current: 4 A or greater
Maximum collector-emitter breakdown voltage: 80 V or greater
Maximum power dissipation: 40 W or greater
DC current gain (hFE): 750 or greater at specified operating conditions
Maximum collector cutoff current: within acceptable range

Mechanical Compatibility Criteria:

Mounting type: Through Hole
Package compatibility: TO-126-3 or equivalent footprint (TO-225AA, SOT-32-3)

All substitute parts listed maintain these electrical and mechanical parameters, ensuring functional equivalence within the KSE702S application envelope.

Parameter Comparison

Parameter	KSE702S	MJE702G	MJE703G	BD680
Manufacturer	onsemi	onsemi	onsemi	STMicroelectronics
Transistor Type	PNP - Darlington	PNP - Darlington	PNP - Darlington	PNP - Darlington
Current - Collector (Ic) (Max)	4 A	4 A	4 A	4 A
Voltage - Collector Emitter Breakdown (Max)	80 V	80 V	80 V	80 V
Power - Max	40 W	40 W	40 W	40 W
DC Current Gain (hFE) (Min) @ Ic, Vce	750 @ 1.5A, 3V	750 @ 1.5A, 3V	750 @ 2A, 3V	750 @ 1.5A, 3V
Current - Collector Cutoff (Max)	100 µA	100 µA	100 µA	500 µA
Vce Saturation (Max)	2.5V @ 30mA, 1.5A	2.5V @ 30mA, 1.5A	2.8V @ 40mA, 2A	2.5V @ 30mA, 1.5A
Operating Temperature (Max)	150°C (TJ)	150°C (TJ)	150°C (TJ)	150°C (TJ)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-225AA, TO-126-3	TO-225AA, TO-126-3	TO-225AA, TO-126-3	TO-225AA, TO-126-3
Supplier Device Package	TO-126-3	TO-126	TO-126	SOT-32-3
Product Status	Obsolete	Obsolete	Obsolete	Active
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

MJE702G (onsemi): This part provides direct electrical equivalence to the KSE702S with identical maximum ratings and DC current gain specifications. MJE702G is ROHS3 compliant and operates across an extended temperature range of -55°C to 150°C, compared to the KSE702S specification of 150°C maximum. The part is classified as obsolete but maintains higher inventory availability (37,790 units) relative to the KSE702S (737 units).

MJE703G (onsemi): This part meets all electrical requirements with identical maximum ratings. MJE703G is ROHS3 compliant and operates across -55°C to 150°C. The DC current gain specification is measured at 2A collector current versus 1.5A for the KSE702S, and Vce saturation is specified at 2.8V versus 2.5V. These variations remain within acceptable substitution parameters. Inventory availability is 2,400 units.

BD680 (STMicroelectronics): This part maintains electrical equivalence across all critical parameters and is classified as active product status, providing long-term procurement assurance. BD680 is ROHS3 compliant and operates at 150°C maximum junction temperature. The collector cutoff current specification is 500µA compared to 100µA for the KSE702S. The package is supplied as SOT-32-3 rather than TO-126-3, requiring verification of mechanical compatibility with existing PCB layouts. Inventory availability is 8,200 units.

Frequently Asked Questions (FAQ)

Q: Can MJE702G be used as a direct replacement for KSE702S?

A: Yes. MJE702G maintains identical electrical specifications for maximum collector current (4 A), collector-emitter breakdown voltage (80 V), power dissipation (40 W), and DC current gain (750 minimum). Both parts use TO-126-3 packaging and through-hole mounting. The extended operating temperature range of MJE702G (-55°C to 150°C) provides additional margin compared to the KSE702S specification.

Q: What is the difference between MJE702G and MJE703G?

A: Both parts meet the KSE702S electrical requirements. MJE703G specifies DC current gain measurement at 2A collector current and 2.8V Vce saturation, compared to MJE702G at 1.5A and 2.5V respectively. Both operate across -55°C to 150°C. Selection between these parts depends on specific circuit operating point requirements.

Q: Is BD680 mechanically compatible with KSE702S?

A: BD680 uses SOT-32-3 packaging while KSE702S uses TO-126-3. Although both are through-hole packages with TO-225AA compatibility, the physical pin configuration and PCB footprint differ. Mechanical compatibility must be verified against the specific PCB layout before substitution.

Q: Why is BD680 recommended despite different packaging?

A: BD680 is the only substitute part with active product status, ensuring long-term availability and manufacturing continuity. All electrical parameters remain equivalent to KSE702S. The packaging difference requires PCB layout verification but does not affect electrical performance.

Q: Are all substitute parts RoHS compliant?

A: MJE702G, MJE703G, and BD680 are all ROHS3 compliant. The KSE702S RoHS status is not specified in the provided data.

Q: What is the significance of collector cutoff current differences?

A: BD680 specifies maximum collector cutoff current at 500µA compared to 100µA for KSE702S and the onsemi substitutes. This parameter affects leakage current behavior in off-state conditions. The higher specification for BD680 remains acceptable for most applications but should be evaluated for circuits with stringent leakage requirements.

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