BD435G Equivalent & Substitute Parts

Part Overview

The BD435G is an NPN bipolar junction transistor manufactured by onsemi, rated for 32 V collector-emitter breakdown voltage and 4 A maximum collector current in a TO-126 through-hole package. This device is classified as obsolete, making identification of suitable substitute components necessary for ongoing design support and production continuity. The BD435G delivers 36 W maximum power dissipation with a 3 MHz transition frequency, suitable for general-purpose switching and amplification applications requiring moderate voltage and current ratings.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	4	A
Voltage - Collector Emitter Breakdown (Max)	32	V
Power - Max	36	W
Frequency - Transition	3	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	85 @ 500mA, 1V	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—

Substitute Part Grouping Explanation

Substitution of the BD435G is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN
Maximum collector current (Ic) must equal or exceed 4 A
Maximum collector-emitter breakdown voltage (Vce) must equal or exceed 32 V
Maximum power dissipation must equal or exceed 36 W
Transition frequency must equal or exceed 3 MHz
DC current gain (hFE) must meet or exceed 85 @ 500mA, 1V
Operating temperature range must encompass -55°C to 150°C

Mechanical Compatibility Criteria:

Mounting type must be through-hole
Package must be TO-126-3 (TO-225AA equivalent)

The BD437G satisfies all substitution criteria. While the BD437G exhibits higher maximum collector-emitter breakdown voltage (45 V versus 32 V), this represents an upward-compatible rating that does not restrict application in circuits designed for the BD435G. All other electrical parameters remain equivalent or superior.

Parameter Comparison

Parameter	BD435G	BD437G	Unit
Transistor Type	NPN	NPN	—
Current - Collector (Ic) (Max)	4	4	A
Voltage - Collector Emitter Breakdown (Max)	32	45	V
Current - Collector Cutoff (Max)	100	100	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	85 @ 500mA, 1V	85 @ 500mA, 1V	—
Power - Max	36	36	W
Frequency - Transition	3	3	MHz
Operating Temperature Range	-55 to 150	-55 to 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 classified as obsolete, necessitating transition to an active product for new designs and ongoing production support. The BD437G is an active product manufactured by onsemi and provides direct electrical and mechanical compatibility with the BD435G.

Both devices maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory alignment. The BD437G's higher collector-emitter breakdown voltage (45 V) provides enhanced voltage margin without compromising performance in applications originally specified for the BD435G's 32 V rating.

Selection of the BD437G as a substitute eliminates obsolescence risk while maintaining full functional equivalence across all critical electrical parameters and mechanical form factors.

Frequently Asked Questions (FAQ)

Q: Can the BD437G directly replace the BD435G in existing circuit designs?

A: Yes. The BD437G meets or exceeds all electrical specifications of the BD435G, including collector current, power dissipation, transition frequency, and current gain. Both devices share identical TO-126-3 package geometry and through-hole mounting configuration. The higher breakdown voltage of the BD437G (45 V versus 32 V) represents an upward-compatible rating.

Q: What is the primary difference between the BD435G and BD437G?

A: The maximum collector-emitter breakdown voltage differs: BD435G is rated 32 V, while BD437G is rated 45 V. All other electrical parameters remain identical. This voltage difference does not restrict substitution in circuits designed for the lower-rated device.

Q: Are there any compliance or regulatory differences between these devices?

A: No. Both the BD435G and BD437G are ROHS3 compliant and REACH unaffected. Regulatory status is equivalent.

Q: Why is the BD435G classified as obsolete?

A: Product status is determined by manufacturer lifecycle decisions. The BD437G, as an active product, provides continued availability and manufacturing support.

Q: Are the saturation voltage characteristics identical between these devices?

A: No. The BD435G specifies 500 mV saturation voltage at 200 mA base current and 2 A collector current. The BD437G specifies 800 mV saturation voltage at 300 mA base current and 3 A collector current. These measurements are taken at different operating points and do not prevent substitution.

Q: Can the BD437G be used in high-frequency applications?

A: Both devices share a 3 MHz transition frequency specification. Application suitability depends on circuit design requirements, not on differences between these two devices.

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