BD435STU Equivalent & Substitute Parts

Part Overview

The BD435STU is an NPN bipolar junction transistor manufactured by onsemi, rated for 32 V collector-emitter breakdown voltage and 4 A maximum collector current. This device is packaged in a TO-126-3 through-hole configuration and is rated for 36 W maximum power dissipation with a transition frequency of 3 MHz. The BD435STU is classified as obsolete, making identification of equivalent substitute parts necessary for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	32	V
Current - Collector (Ic) (Max)	4	A
Power - Max	36	W
Frequency - Transition	3	MHz
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—
Operating Temperature (Max)	150	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the BD435STU is determined by electrical and mechanical parameter equivalence within the NPN bipolar transistor category. The critical parameters governing substitution are:

Transistor Type: NPN configuration
Voltage Rating: 32 V collector-emitter breakdown voltage (maximum)
Current Rating: 4 A maximum collector current
Power Dissipation: 36 W maximum
Frequency Response: 3 MHz transition frequency
Package Type: TO-126-3 through-hole mounting
Compliance: ROHS3 compliance and REACH unaffected status

The BD435G qualifies as a direct substitute based on matching all primary electrical ratings and through-hole packaging. Both devices share the same base product number (BD435) and are manufactured by onsemi. The BD435G maintains identical voltage, current, and power specifications while offering expanded operating temperature range and improved DC current gain characteristics.

Parameter Comparison

Parameter	BD435STU	BD435G	Unit
Transistor Type	NPN	NPN	—
Voltage - Collector Emitter Breakdown (Max)	32	32	V
Current - Collector (Ic) (Max)	4	4	A
Vce Saturation (Max) @ Ib, Ic	500mV @ 200mA, 2A	500mV @ 200mA, 2A	—
Current - Collector Cutoff (Max)	100µA	100µA	—
Power - Max	36	36	W
Frequency - Transition	3	3	MHz
Operating Temperature (Max)	150	150	°C
Mounting Type	Through Hole	Through Hole	—
Package / Case	TO-126-3	TO-126-3	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	—
REACH Status	REACH Unaffected	REACH Unaffected	—

Engineering Selection Recommendations

The BD435G is a direct electrical and mechanical equivalent to the BD435STU. Both devices are manufactured by onsemi and maintain identical ratings for voltage, current, power, and frequency specifications. Both are ROHS3 compliant and REACH unaffected, satisfying regulatory requirements for modern applications.

The BD435STU is classified as obsolete, whereas the BD435G maintains the same obsolete status. Selection between these devices should be based on availability and procurement lead times. The BD435G offers expanded operating temperature range (-55°C to 150°C versus 150°C maximum for the BD435STU), providing additional thermal margin in applications requiring lower temperature operation.

Both devices are suitable for direct substitution in through-hole PCB designs requiring NPN transistor functionality at 32 V, 4 A ratings. No circuit modifications are required when transitioning from BD435STU to BD435G.

Frequently Asked Questions (FAQ)

Q: Can the BD435G replace the BD435STU in existing designs?

A: Yes. The BD435G is a direct substitute for the BD435STU. Both devices share identical electrical ratings (32 V, 4 A, 36 W, 3 MHz) and are packaged in TO-126-3 through-hole configuration. No circuit modifications are required.

Q: What is the primary difference between BD435STU and BD435G?

A: The BD435G provides expanded operating temperature range (-55°C to 150°C) compared to the BD435STU (maximum 150°C). Both devices maintain identical electrical specifications and compliance certifications.

Q: Are both devices RoHS compliant?

A: Yes. Both the BD435STU and BD435G are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements for electronic components.

Q: Can these devices be used interchangeably on the same PCB?

A: Yes. Both devices use identical TO-126-3 through-hole packaging and pin configuration, allowing direct PCB footprint compatibility without layout modifications.

Q: Why is the BD435STU classified as obsolete?

A: The BD435STU is listed as obsolete by the manufacturer. The BD435G serves as the current equivalent for ongoing procurement and design support.

Q: What applications are suitable for these transistors?

A: These NPN transistors are suitable for general-purpose switching and amplification applications requiring 32 V, 4 A ratings. Specific application suitability depends on circuit design requirements and thermal management provisions.

Q: Are there other substitute options beyond BD435G?

A: The BD435G documentation references BD437G as an additional substitute. Verification of BD437G electrical specifications against application requirements is necessary for substitution consideration.

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