KSB1149OS Equivalent & Substitute Parts

Part Overview

The KSB1149OS is a PNP Darlington bipolar junction transistor manufactured by onsemi, rated for 100 V collector-emitter breakdown voltage and 3 A maximum collector current in a TO-126-3 through-hole package. This device is classified as obsolete product status. Locating equivalent substitute parts is necessary due to the obsolete classification, which may result in limited availability or discontinuation of the original component from standard distribution channels.

Key Parameters

Parameter	Value
Transistor Type	PNP - Darlington
Voltage - Collector Emitter Breakdown (Max)	100 V
Current - Collector (Ic) (Max)	3 A
Power - Max	1.3 W
Vce Saturation (Max)	1.2 V @ 1.5 mA, 1.5 A
DC Current Gain (hFE) (Min)	2000 @ 1.5 A, 2 V
Current - Collector Cutoff (Max)	10 µA
Mounting Type	Through Hole
Package / Case	TO-126-3
Operating Temperature (Max)	150°C

Substitute Part Grouping Explanation

Substitution of the KSB1149OS is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor type must be PNP - Darlington configuration
Voltage - Collector Emitter Breakdown rating must be equal to or greater than 100 V
Current - Collector (Ic) maximum rating must be equal to or greater than 3 A
Mounting type must be Through Hole
Package must be compatible with TO-126-3 footprint

Secondary Compatibility Factors:

Operating temperature range must support maximum junction temperature of 150°C
Vce saturation characteristics must be suitable for the application circuit
DC current gain (hFE) specifications must meet circuit design requirements

The BD682 qualifies as a substitute part because it maintains the same transistor type (PNP - Darlington), exceeds the voltage rating (100 V), exceeds the current rating (4 A versus 3 A), uses compatible through-hole mounting, and is housed in a TO-126 package compatible with TO-126-3 footprints.

Parameter Comparison

Parameter	KSB1149OS	BD682
Transistor Type	PNP - Darlington	PNP - Darlington
Voltage - Collector Emitter Breakdown (Max)	100 V	100 V
Current - Collector (Ic) (Max)	3 A	4 A
Power - Max	1.3 W	40 W
Vce Saturation (Max)	1.2 V @ 1.5 mA, 1.5 A	2.5 V @ 30 mA, 1.5 A
Current - Collector Cutoff (Max)	10 µA	500 µA
DC Current Gain (hFE) (Min)	2000 @ 1.5 A, 2 V	750 @ 1.5 A, 3 V
Operating Temperature (Max)	150°C	150°C
Mounting Type	Through Hole	Through Hole
Package / Case	TO-126-3	TO-126
Product Status	Obsolete	Obsolete

Engineering Selection Recommendations

BD682 as Substitute:

The BD682 is electrically and mechanically compatible with the KSB1149OS for applications requiring PNP Darlington transistor functionality at 100 V and 3 A operating points. The BD682 provides higher current capacity (4 A versus 3 A) and significantly higher power dissipation capability (40 W versus 1.3 W), making it suitable for applications where the KSB1149OS is specified.

Both parts share obsolete product status classification. The KSB1149OS carries REACH Unaffected compliance status. The BD682 is classified as RoHS non-compliant, which may be a consideration in applications subject to RoHS requirements.

The BD682 exhibits higher collector cutoff current (500 µA versus 10 µA) and lower DC current gain (750 versus 2000), which may affect circuit behavior in applications with tight leakage or gain specifications. The higher Vce saturation voltage of the BD682 (2.5 V versus 1.2 V) results in increased power dissipation during saturation conditions.

Frequently Asked Questions (FAQ)

Q: Can the BD682 directly replace the KSB1149OS in all applications?

A: The BD682 is electrically and mechanically compatible for applications operating at or below the KSB1149OS specifications. However, differences in DC current gain (hFE), collector cutoff current (ICBO), and Vce saturation voltage must be evaluated against circuit design requirements. Applications with tight gain or leakage specifications may require circuit analysis.

Q: Are the TO-126 and TO-126-3 packages physically interchangeable?

A: Both packages use the same TO-126 footprint for through-hole mounting. The TO-126-3 designation indicates a three-lead configuration, which is standard for transistor packages. Physical board-level compatibility is maintained between these package variants.

Q: What is the significance of the higher power rating of the BD682?

A: The BD682 is rated for 40 W maximum power dissipation compared to 1.3 W for the KSB1149OS. This higher rating provides thermal margin in applications with elevated power dissipation. However, the actual power dissipation in a given circuit is determined by circuit design, not the component rating.

Q: How do the DC current gain differences affect circuit operation?

A: The KSB1149OS specifies a minimum hFE of 2000 at 1.5 A and 2 V, while the BD682 specifies 750 at 1.5 A and 3 V. Lower gain in the BD682 requires higher base current to achieve the same collector current. Applications using base current limiting or gain-dependent biasing must account for this difference.

Q: What compliance considerations apply to substitution?

A: The KSB1149OS is REACH Unaffected. The BD682 is RoHS non-compliant. Applications subject to RoHS directives or REACH regulations must verify compliance requirements before substitution.

Q: Why is the collector cutoff current (ICBO) higher in the BD682?

A: The BD682 specifies maximum ICBO of 500 µA compared to 10 µA for the KSB1149OS. Higher leakage current may affect circuit performance in applications sensitive to base-emitter leakage, such as precision switching or low-power standby circuits.

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