BD440G Equivalent & Substitute Parts

Part Overview

The BD440G is a PNP bipolar junction transistor manufactured by onsemi, rated for 60 V collector-emitter breakdown voltage and 4 A maximum collector current. This device is packaged in TO-126 through-hole configuration and is designed for general-purpose switching and amplification applications requiring 36 W power dissipation capability.

The BD440G is classified as an obsolete product. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for legacy systems utilizing this component.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	4	A
Voltage - Collector Emitter Breakdown (Max)	60	V
Power - Max	36	W
Frequency - Transition	3	MHz
Mounting Type	Through Hole	—
Operating Temperature Range	-55 to 150	°C
DC Current Gain (hFE) Min	40	@ 500mA, 1V

Substitute Part Grouping Explanation

Substitution eligibility for the BD440G is determined by the following critical parameters:

Primary Matching Criteria:

Transistor type: PNP polarity
Maximum collector current: 4 A minimum
Maximum power dissipation: 36 W minimum
Transition frequency: 3 MHz minimum
Mounting type: Through hole configuration
Operating temperature range: Support for upper limit of 150°C

Secondary Compatibility Factors:

Collector-emitter breakdown voltage: 60 V or higher
DC current gain (hFE): 40 or higher at specified test conditions
Collector cutoff current (ICBO): 100 µA maximum
Vce saturation characteristics within acceptable operating margins

Parts are grouped as direct equivalents when all primary criteria are met with identical or superior electrical ratings. Parts with reduced voltage ratings or modified saturation characteristics are classified as similar alternatives requiring application-level verification of voltage headroom.

Parameter Comparison

Parameter	BD440G (Main)	BD440S (Direct)	BD438 (Similar)	Unit
Manufacturer	onsemi	onsemi	STMicroelectronics	—
Transistor Type	PNP	PNP	PNP	—
Current - Collector (Ic) Max	4	4	4	A
Voltage - Collector Emitter Breakdown (Max)	60	60	45	V
Vce Saturation (Max)	800mV @ 300mA, 3A	800mV @ 200mA, 2A	600mV @ 200mA, 2A	—
Current - Collector Cutoff (Max)	100µA	100µA	100µA	—
DC Current Gain (hFE) Min	40 @ 500mA, 1V	40 @ 500mA, 1V	30 @ 10mA, 5V	—
Power - Max	36	36	36	W
Frequency - Transition	3	3	3	MHz
Operating Temperature (TJ)	-55 to 150	150	150	°C
Mounting Type	Through Hole	Through Hole	Through Hole	—
Package / Case	TO-225AA, TO-126-3	TO-225AA, TO-126-3	TO-225AA, TO-126-3	—
Supplier Device Package	TO-126	TO-126-3	SOT-32-3	—
Product Status	Obsolete	Last Time Buy	Active	—
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

BD440S (Direct Equivalent - onsemi):

The BD440S is a direct equivalent to the BD440G, manufactured by the same supplier (onsemi) with identical electrical ratings for collector current (4 A), collector-emitter breakdown voltage (60 V), power dissipation (36 W), and transition frequency (3 MHz). Both devices share the same base product number (BD440) and are housed in compatible TO-126-3 through-hole packages.

The BD440S is classified as Last Time Buy status, indicating limited future availability. This part is ROHS3 compliant and REACH unaffected. The primary distinction is the supplier device package designation (TO-126-3 versus TO-126), which represents a packaging refinement rather than a functional change. Pin configuration and electrical performance remain equivalent.

BD438 (Similar Alternative - STMicroelectronics):

The BD438 is manufactured by STMicroelectronics and shares the same collector current (4 A), power dissipation (36 W), and transition frequency (3 MHz) as the BD440G. However, the collector-emitter breakdown voltage is reduced to 45 V, compared to 60 V for the BD440G. This represents a 25% reduction in voltage rating.

The BD438 is classified as Active product status, ensuring ongoing availability and supply chain support. This part is ROHS3 compliant and REACH unaffected. The device is packaged in SOT-32-3 configuration, which maintains through-hole mounting compatibility but differs from the TO-126 package footprint.

Selection of the BD438 requires confirmation that the application circuit operates within 45 V maximum collector-emitter voltage limits. Applications designed for the full 60 V rating of the BD440G cannot use the BD438 without circuit redesign or voltage derating.

Frequently Asked Questions (FAQ)

Q: Can BD440S be used as a direct replacement for BD440G in existing designs?

A: Yes. The BD440S is electrically equivalent to the BD440G with identical ratings for collector current (4 A), collector-emitter breakdown voltage (60 V), power dissipation (36 W), and transition frequency (3 MHz). Both devices are manufactured by onsemi and share the same base product number. The package designation change from TO-126 to TO-126-3 represents a supplier packaging refinement with no functional impact. Pin configuration and electrical performance are equivalent.

Q: What is the primary limitation of using BD438 as a substitute for BD440G?

A: The BD438 has a reduced collector-emitter breakdown voltage rating of 45 V compared to 60 V for the BD440G. This 25% reduction in voltage rating means the BD438 cannot be used in applications where the circuit operates at or near 60 V. The BD438 is suitable only for applications with confirmed maximum collector-emitter voltages of 45 V or lower.

Q: Are there package compatibility issues between BD440G and its substitutes?

A: The BD440G and BD440S both use TO-126-3 through-hole packages with compatible pin configurations and PCB footprints. The BD438 uses a SOT-32-3 package, which is also a through-hole configuration but has a different physical footprint. PCB layout modifications are required if substituting BD440G with BD438 due to package differences.

Q: What is the difference between BD440G and BD440S in terms of product availability?

A: BD440G is classified as Obsolete, indicating no further production or availability. BD440S is classified as Last Time Buy, meaning limited quantities remain available from existing inventory before production ends. BD438 is classified as Active, ensuring ongoing production and supply chain availability. For new designs or long-term production requirements, BD438 is the recommended choice due to active status.

Q: Are all three parts ROHS3 compliant?

A: BD440S and BD438 are both explicitly ROHS3 compliant. The BD440G does not specify RoHS status in the provided data. All three parts are REACH unaffected. For applications requiring ROHS3 compliance certification, BD440S or BD438 are the appropriate selections.

Q: What are the DC current gain differences between these parts?

A: BD440G and BD440S both specify minimum DC current gain (hFE) of 40 at 500 mA collector current and 1 V collector-emitter voltage. BD438 specifies minimum DC current gain of 30 at 10 mA collector current and 5 V collector-emitter voltage. The different test conditions reflect manufacturer specifications and do not indicate functional incompatibility for typical switching applications.

Q: Can BD440G be used in applications requiring operation below -55°C?

A: No. The BD440G operating temperature range is specified as -55°C to 150°C. BD440S specifies only the upper limit of 150°C without a lower temperature bound in the provided data. BD438 also specifies only 150°C upper limit. Applications requiring operation below -55°C cannot use any of these three parts.

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