KSA1381ES Equivalent & Substitute Parts

Part Overview

The KSA1381ES is a PNP bipolar junction transistor manufactured by onsemi, rated for 300 V collector-emitter breakdown voltage and 100 mA maximum collector current in a TO-126-3 through-hole package. This device is classified as obsolete, necessitating identification of active equivalent and substitute components for ongoing design requirements and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Voltage - Collector Emitter Breakdown (Max)	300	V
Current - Collector (Ic) (Max)	100	mA
Vce Saturation (Max) @ Ib, Ic	600mV @ 2mA, 20mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10mA, 10V	—
Power - Max	7	W
Frequency - Transition	150	MHz
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—

Substitute Part Grouping Explanation

Substitution of the KSA1381ES is determined by the following critical parameters: transistor type (PNP), collector-emitter breakdown voltage (300 V minimum), collector current rating, power dissipation capability, DC current gain, and through-hole mounting compatibility.

Direct Equivalent (Identical Electrical and Mechanical Specifications): The KSA1381ESTU maintains all electrical specifications of the KSA1381ES with identical ratings for voltage, current, gain, and power. The primary distinction is packaging format (tube versus loose) and active product status.

Similar Substitutes (Higher Current and Power Ratings): The MJE350 series devices (MJE350 and MJE350G) share the 300 V collector-emitter breakdown voltage and PNP configuration but feature higher maximum collector current (500 mA) and power dissipation (20 W and 20.8 W respectively). These components are suitable for applications where the KSA1381ES current and power ratings are insufficient, provided circuit design accommodates the higher ratings.

Parameter Comparison

Parameter	KSA1381ES	KSA1381ESTU	MJE350G (onsemi)	MJE350 (STMicroelectronics)
Manufacturer	onsemi	onsemi	onsemi	STMicroelectronics
Product Status	Obsolete	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP
Voltage - Collector Emitter Breakdown (Max)	300 V	300 V	300 V	300 V
Current - Collector (Ic) (Max)	100 mA	100 mA	500 mA	500 mA
Power - Max	7 W	7 W	20 W	20.8 W
Frequency - Transition	150 MHz	150 MHz	—	—
Operating Temperature Range	-55 to 150 °C	-55 to 150 °C	-65 to 150 °C	—
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Supplier Device Package	TO-126-3	TO-126-3	TO-126	SOT-32-3
RoHS Status	—	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications): The KSA1381ESTU is the primary substitute for the obsolete KSA1381ES. Both components share identical electrical ratings and through-hole mounting configuration. The KSA1381ESTU carries active product status and ROHS3 compliance, making it suitable for new designs and production continuity without circuit modification.

For Higher Current/Power Applications: The MJE350G (onsemi) and MJE350 (STMicroelectronics) are suitable substitutes when application requirements exceed the 100 mA collector current or 7 W power dissipation limits of the KSA1381ES. Both MJE350 variants maintain the 300 V breakdown voltage specification and through-hole mounting. The MJE350G maintains the TO-126 package footprint compatibility, while the STMicroelectronics MJE350 uses a SOT-32-3 package requiring PCB layout modification. All substitute options carry active product status and ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can the KSA1381ESTU be used as a direct replacement for the KSA1381ES?

A: Yes. The KSA1381ESTU maintains identical electrical specifications including 300 V breakdown voltage, 100 mA maximum collector current, 7 W power rating, 150 MHz transition frequency, and -55 to 150 °C operating temperature range. Both use TO-126-3 through-hole packaging. The primary difference is packaging format (tube) and active product status.

Q: What are the limitations when substituting MJE350 series devices for the KSA1381ES?

A: The MJE350 series devices feature higher collector current (500 mA) and power dissipation (20 W and 20.8 W) ratings. While these higher ratings do not prevent substitution in circuits designed for the KSA1381ES specifications, circuit designers must verify that the higher current and power capabilities do not introduce unintended operational changes. The MJE350 series lacks specified transition frequency data.

Q: Are there package compatibility considerations between substitute options?

A: The KSA1381ESTU and MJE350G (onsemi) both use TO-126 package variants suitable for existing TO-126-3 PCB layouts. The MJE350 (STMicroelectronics) uses SOT-32-3 packaging, which requires PCB layout modification and is not pin-compatible with the original TO-126-3 footprint.

Q: Do all substitute parts meet current regulatory compliance requirements?

A: The KSA1381ESTU, MJE350G, and MJE350 (STMicroelectronics) all carry ROHS3 compliance and REACH Unaffected status. The original KSA1381ES does not specify RoHS status but maintains REACH Unaffected classification.

Q: What is the temperature operating range difference between the KSA1381ES and MJE350 variants?

A: The KSA1381ES and KSA1381ESTU operate from -55 to 150 °C. The MJE350G extends the lower temperature limit to -65 °C. The STMicroelectronics MJE350 specifies only a maximum temperature of 150 °C without a defined minimum range.

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