BD436S Equivalent & Substitute Parts

Part Overview

The BD436S is a PNP 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 TO-126-3 through-hole configuration and is designed for general-purpose switching and amplification applications requiring 36 W power dissipation capability.

The BD436S is classified as an obsolete product. Identification of equivalent and substitute parts is necessary to support ongoing maintenance, repair, and production requirements for systems utilizing this component. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) (Max)	4	A
Voltage - Collector Emitter Breakdown (Max)	32	V
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 BD436S is determined by the following critical parameters:

Electrical Compatibility Requirements:

Transistor type must be PNP
Maximum collector current must be greater than or equal to 4 A
Maximum collector-emitter breakdown voltage must be greater than or equal to 32 V
Maximum power dissipation must be greater than or equal to 36 W
Transition frequency must be greater than or equal to 3 MHz

Mechanical Compatibility Requirements:

Mounting type must be through-hole
Package must be compatible with TO-126-3 footprint

Compliance Requirements:

RoHS3 compliance required
REACH unaffected status required

The BD438G meets all electrical and mechanical compatibility criteria. This device provides higher voltage rating (45 V) and improved DC current gain characteristics while maintaining identical maximum collector current (4 A), power dissipation (36 W), and transition frequency (3 MHz). The BD438G is classified as an active product, ensuring continued availability and supply chain support.

Parameter Comparison

Parameter	BD436S	BD438G	Unit
Transistor Type	PNP	PNP	—
Current - Collector (Ic) (Max)	4	4	A
Voltage - Collector Emitter Breakdown (Max)	32	45	V
Current - Collector Cutoff (Max)	100	100	µA
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	—
Product Status	Obsolete	Active	—

Engineering Selection Recommendations

The BD438G is a direct substitute for the BD436S in applications where the circuit design accommodates the higher collector-emitter breakdown voltage rating of 45 V. Both devices share identical maximum collector current (4 A), power dissipation (36 W), transition frequency (3 MHz), and through-hole TO-126-3 packaging.

The BD438G offers the advantage of active product status, ensuring long-term availability and supply chain continuity. Both devices maintain ROHS3 compliance and REACH unaffected status, satisfying regulatory requirements for new designs and legacy system support.

Selection of the BD438G is appropriate for new designs and replacement applications. The higher voltage rating provides additional design margin in circuits operating below 32 V. In applications where the circuit design is voltage-constrained to 32 V operation, the BD438G remains functionally compatible due to its higher voltage capability.

Frequently Asked Questions (FAQ)

Q: Can the BD438G directly replace the BD436S in existing circuit designs?

A: The BD438G is electrically compatible with the BD436S for applications operating at or below 32 V. The BD438G's higher breakdown voltage rating (45 V) does not create incompatibility in circuits designed for 32 V operation. Both devices share identical maximum collector current, power dissipation, and transition frequency specifications. Physical footprint compatibility is maintained through identical TO-126-3 through-hole packaging.

Q: What are the key differences between the BD436S and BD438G?

A: The primary difference is the maximum collector-emitter breakdown voltage: BD436S is rated at 32 V, while BD438G is rated at 45 V. The BD438G also exhibits higher DC current gain (85 @ 500mA, 1V compared to 40 @ 10mA, 5V) and higher saturation voltage (700mV @ 300mA, 3A compared to 500mV @ 200mA, 2A). The BD438G is an active product, whereas the BD436S is obsolete.

Q: Are there any package compatibility concerns when substituting the BD438G for the BD436S?

A: No. Both devices utilize the TO-126-3 through-hole package configuration. Pin assignments and mechanical dimensions are compatible, allowing direct board-level substitution without layout modifications.

Q: Does the BD438G meet the same compliance standards as the BD436S?

A: Yes. Both the BD436S and BD438G are ROHS3 compliant and REACH unaffected. Regulatory compliance is maintained when substituting the BD438G for the BD436S.

Q: Why is the BD436S classified as obsolete?

A: The BD436S is listed as an obsolete product by the manufacturer. The BD438G represents the active equivalent in onsemi's current product portfolio, offering improved specifications and continued manufacturing support.

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