KSC2688OS Equivalent & Substitute Parts

Part Overview

The KSC2688OS is an NPN bipolar junction transistor manufactured by onsemi, rated for 300 V collector-emitter breakdown voltage and 200 mA maximum collector current. This device is packaged in a TO-126 through-hole configuration and is designed for general-purpose switching and amplification applications requiring moderate voltage and current ratings.

The KSC2688OS is classified as obsolete. Locating equivalent substitute parts is necessary to maintain design continuity and ensure component availability for new production runs, repairs, and system upgrades where this transistor was originally specified.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	1.25	W
Frequency - Transition	80	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	60 @ 10mA, 10V	—
Vce Saturation (Max) @ Ib, Ic	1.5V @ 5mA, 50mA	—
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—

Substitute Part Grouping Explanation

Substitution of the KSC2688OS is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN
Collector-emitter breakdown voltage must be equal to or greater than 300 V
Maximum collector current must be equal to or greater than 200 mA
DC current gain (hFE) must meet or exceed 60 @ 10mA, 10V
Vce saturation characteristics must support the original circuit requirements

Mechanical Compatibility Criteria:

Mounting type must be through-hole
Package must be TO-126 or TO-126-3 configuration
Pin configuration must be compatible with existing PCB layouts

The KSC3503DS meets these substitution criteria and is identified as an equivalent part for the KSC2688OS.

Parameter Comparison

Parameter	KSC2688OS	KSC3503DS	Compatibility
Transistor Type	NPN	NPN	Match
Voltage - Collector Emitter Breakdown (Max)	300 V	300 V	Match
Current - Collector (Ic) (Max)	200 mA	100 mA	Substitute rated lower
Power - Max	1.25 W	7 W	Substitute rated higher
Frequency - Transition	80 MHz	150 MHz	Substitute rated higher
DC Current Gain (hFE) (Min) @ Ic, Vce	60 @ 10mA, 10V	60 @ 10mA, 10V	Match
Vce Saturation (Max) @ Ib, Ic	1.5V @ 5mA, 50mA	600mV @ 2mA, 20mA	Substitute performs better
Mounting Type	Through Hole	Through Hole	Match
Package / Case	TO-126-3	TO-126-3	Match
Operating Temperature	150°C (TJ)	-55°C ~ 150°C (TJ)	Substitute range wider
Product Status	Obsolete	Active	Substitute actively produced

Engineering Selection Recommendations

The KSC3503DS is an active production substitute for the obsolete KSC2688OS. Both devices share identical voltage ratings (300 V), matching DC current gain specifications (60 @ 10mA, 10V), and compatible through-hole TO-126-3 packaging.

The KSC3503DS exhibits superior performance characteristics in several areas: maximum power dissipation is rated at 7 W compared to 1.25 W, transition frequency is 150 MHz versus 80 MHz, and Vce saturation is lower at 600 mV. The KSC3503DS operates across a wider temperature range (-55°C to 150°C) and carries RoHS3 compliance certification.

The primary design consideration is that the KSC3503DS has a maximum collector current rating of 100 mA, which is lower than the KSC2688OS specification of 200 mA. Circuit designs operating at collector currents exceeding 100 mA require evaluation to confirm the substitute part remains within safe operating limits.

Both parts carry REACH Unaffected status and EAR99 export classification. The KSC3503DS is currently in active production with confirmed inventory availability.

Frequently Asked Questions (FAQ)

Q: Can the KSC3503DS directly replace the KSC2688OS in all applications?

A: Direct substitution is valid for circuits operating at collector currents of 100 mA or below. Applications requiring the full 200 mA collector current rating of the KSC2688OS must be re-evaluated, as the KSC3503DS is rated for a maximum of 100 mA. Voltage ratings, current gain, and package compatibility are identical.

Q: What are the key electrical differences between these parts?

A: The KSC3503DS provides higher power dissipation capability (7 W versus 1.25 W), higher transition frequency (150 MHz versus 80 MHz), and lower saturation voltage (600 mV versus 1.5 V). The maximum collector current is lower in the substitute (100 mA versus 200 mA).

Q: Are the packages physically identical?

A: Both the KSC2688OS and KSC3503DS use the TO-126-3 through-hole package configuration. Pin assignments and PCB footprints are compatible, allowing direct physical substitution without layout modifications.

Q: What is the product status difference, and why does it matter?

A: The KSC2688OS is classified as obsolete, meaning onsemi no longer manufactures this part. The KSC3503DS is in active production status, ensuring long-term availability and supply chain continuity for new designs and ongoing production requirements.

Q: Does the KSC3503DS meet current compliance standards?

A: The KSC3503DS is RoHS3 compliant and carries REACH Unaffected status. Both parts are classified as EAR99 for export purposes. The substitute part meets current environmental and regulatory requirements.

Q: What should I verify before implementing this substitution?

A: Confirm that your circuit design operates at collector currents not exceeding 100 mA. Verify that the improved saturation voltage and higher transition frequency do not negatively impact circuit performance. Validate thermal management, as the higher power rating may affect heat dissipation requirements.

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