BD675 Equivalent & Substitute Parts

Part Overview

The BD675 is an NPN Darlington bipolar junction transistor manufactured by onsemi, designed for through-hole applications in TO-126 packaging. This device is rated for 45 V collector-emitter breakdown voltage and 4 A maximum collector current, with a maximum power dissipation of 40 W. The BD675 is classified as obsolete, making identification of equivalent substitute parts necessary for ongoing design support and component procurement in legacy systems or new designs requiring compatible alternatives.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN - Darlington	—
Current - Collector (Ic) (Max)	4	A
Voltage - Collector Emitter Breakdown (Max)	45	V
Vce Saturation (Max) @ Ib, Ic	2.5V @ 30mA, 1.5A	—
Current - Collector Cutoff (Max)	500	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	750 @ 1.5A, 3V	—
Power - Max	40	W
Operating Temperature	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-225AA, TO-126-3	—

Substitute Part Grouping Explanation

Substitution of the BD675 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor type must be NPN - Darlington configuration
Maximum collector current (Ic) must equal or exceed 4 A
Collector-emitter breakdown voltage (VCEO) must equal or exceed 45 V
DC current gain (hFE) must meet or exceed 750 @ 1.5A, 3V
Vce saturation characteristics must be compatible with 2.5V @ 30mA, 1.5A
Collector cutoff current must not exceed 500 µA
Maximum power dissipation must equal or exceed 40 W

Mechanical Compatibility Criteria:

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

The BD677 meets these substitution criteria with equivalent electrical performance and enhanced voltage rating, while maintaining identical current, gain, and power specifications.

Parameter Comparison

Parameter	BD675 (onsemi)	BD677 (STMicroelectronics)	Unit
Transistor Type	NPN - Darlington	NPN - Darlington	—
Current - Collector (Ic) (Max)	4	4	A
Voltage - Collector Emitter Breakdown (Max)	45	60	V
Vce Saturation (Max) @ Ib, Ic	2.5V @ 30mA, 1.5A	2.5V @ 30mA, 1.5A	—
Current - Collector Cutoff (Max)	500	500	µA
DC Current Gain (hFE) (Min) @ Ic, Vce	750 @ 1.5A, 3V	750 @ 1.5A, 3V	—
Power - Max	40	40	W
Operating Temperature (Max)	150	150	°C (TJ)
Mounting Type	Through Hole	Through Hole	—
Package / Case	TO-225AA, TO-126-3	TO-225AA, TO-126-3	—
Product Status	Obsolete	Active	—
RoHS Status	RoHS non-compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

BD677 as Primary Substitute:

The BD677 manufactured by STMicroelectronics is a direct functional equivalent to the BD675. Both devices share identical electrical specifications for collector current (4 A), saturation voltage (2.5V @ 30mA, 1.5A), current gain (750 @ 1.5A, 3V), power dissipation (40 W), and operating temperature range (maximum 150°C). The BD677 provides an enhanced collector-emitter breakdown voltage rating of 60 V compared to the BD675's 45 V, offering improved voltage margin in applications operating near the original specification limit.

Compliance Advantage:

The BD677 holds ROHS3 compliance status, whereas the BD675 is RoHS non-compliant. For new designs or procurement requiring regulatory compliance with modern environmental standards, the BD677 is the appropriate selection. Both devices maintain REACH Unaffected status and identical EAR99 export classification.

Product Status Consideration:

The BD675 is classified as obsolete, while the BD677 maintains active product status. This distinction ensures long-term component availability and continued manufacturer support for the BD677, making it the preferred choice for both legacy system maintenance and new applications.

Frequently Asked Questions (FAQ)

Q: Can the BD677 directly replace the BD675 in existing circuit designs?

A: Yes. The BD677 is electrically equivalent to the BD675 across all critical parameters: collector current (4 A), saturation voltage (2.5V @ 30mA, 1.5A), DC current gain (750 @ 1.5A, 3V), and power dissipation (40 W). The enhanced voltage rating (60 V vs. 45 V) provides additional design margin without affecting circuit operation. Both devices use identical through-hole mounting and compatible TO-126 packaging.

Q: What is the primary difference between the BD675 and BD677?

A: The BD677 features a higher collector-emitter breakdown voltage rating of 60 V compared to the BD675's 45 V. Additionally, the BD677 is ROHS3 compliant and maintains active product status, whereas the BD675 is obsolete and RoHS non-compliant.

Q: Are there any package compatibility concerns when substituting the BD677 for the BD675?

A: No. Both the BD675 and BD677 are specified for through-hole mounting in TO-126 packaging (TO-225AA, TO-126-3). Physical footprint and pin configuration are identical, allowing direct board-level substitution without layout modifications.

Q: Why is the BD677 rated for 60 V instead of 45 V?

A: The BD677 is manufactured by STMicroelectronics with a higher voltage specification. This difference reflects the manufacturer's design and does not affect compatibility. Applications designed for the BD675's 45 V rating operate safely within the BD677's 60 V specification.

Q: Should the BD677 be selected for new designs?

A: Yes. The BD677 is the appropriate choice for new designs due to its active product status, ROHS3 compliance, and equivalent electrical performance. The BD675's obsolete status makes the BD677 the forward-compatible solution for ongoing component procurement and design continuity.

Q: Are the thermal characteristics identical between these devices?

A: Yes. Both devices specify a maximum operating junction temperature of 150°C and identical power dissipation of 40 W. Thermal management considerations remain unchanged when substituting the BD677 for the BD675.

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