BD179 Equivalent & Substitute Parts

Part Overview

The BD179 is an NPN bipolar junction transistor manufactured by onsemi, rated for 80V collector-emitter breakdown voltage and 3A maximum collector current. This device is designed for through-hole mounting in TO-126 package configuration and operates across a temperature range of -65°C to 150°C. The BD179 is classified as obsolete, necessitating identification of active equivalent components for new designs and ongoing production requirements. Substitute parts must maintain electrical and mechanical compatibility while offering active product status and current manufacturing support.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	3	A
Voltage - Collector Emitter Breakdown (Max)	80	V
Vce Saturation (Max) @ Ib, Ic	800mV @ 100mA, 1A	—
Current - Collector Cutoff (Max)	100	µA (ICBO)
DC Current Gain (hFE) (Min) @ Ic, Vce	63 @ 150mA, 2V	—
Power - Max	30	W
Frequency - Transition	3	MHz
Mounting Type	Through Hole	—
Package / Case	TO-126-3	—
Operating Temperature Range	-65 to 150	°C (TJ)

Substitute Part Grouping Explanation

Substitute parts for the BD179 are identified based on strict parametric equivalence across the following critical specifications:

Electrical Parameters (Must Match):

Transistor Type: NPN
Maximum Collector Current (Ic): 3 A
Collector-Emitter Breakdown Voltage (VCEO): 80 V
Saturation Voltage (Vce Sat): 800mV @ 100mA, 1A
Collector Cutoff Current (ICBO): 100 µA
DC Current Gain (hFE): 63 minimum @ 150mA, 2V
Maximum Power Dissipation: 30 W
Transition Frequency: 3 MHz

Mechanical Parameters (Must Match):

Mounting Type: Through Hole
Package Configuration: TO-126-3

The BD17910STU from Fairchild Semiconductor satisfies all electrical and mechanical equivalence criteria, providing an active product alternative to the obsolete BD179.

Parameter Comparison

Parameter	BD179 (onsemi)	BD17910STU (Fairchild Semiconductor)	Match Status
Transistor Type	NPN	NPN	Equivalent
Current - Collector (Ic) (Max)	3 A	3 A	Equivalent
Voltage - Collector Emitter Breakdown (Max)	80 V	80 V	Equivalent
Vce Saturation (Max) @ Ib, Ic	800mV @ 100mA, 1A	800mV @ 100mA, 1A	Equivalent
Current - Collector Cutoff (Max)	100 µA (ICBO)	100 µA (ICBO)	Equivalent
DC Current Gain (hFE) (Min) @ Ic, Vce	63 @ 150mA, 2V	63 @ 150mA, 2V	Equivalent
Power - Max	30 W	30 W	Equivalent
Frequency - Transition	3 MHz	3 MHz	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Package / Case	TO-126-3	TO-126-3	Equivalent
Operating Temperature Range	-65 to 150°C (TJ)	Up to 150°C (TJ)	Compatible
Product Status	Obsolete	Active	Substitute Advantage

Engineering Selection Recommendations

The BD17910STU from Fairchild Semiconductor is the direct parametric equivalent for the obsolete BD179. Selection of the BD17910STU is based on the following engineering criteria:

Product Status: The BD17910STU maintains active product status with current manufacturing support, whereas the BD179 is classified as obsolete. This ensures long-term availability and supply chain continuity for production applications.

Electrical Equivalence: All critical electrical parameters are identical between the two devices, including collector current rating, breakdown voltage, saturation characteristics, current gain, power dissipation, and transition frequency. These parameters determine functional compatibility in circuit applications.

Mechanical Compatibility: Both devices utilize identical through-hole mounting configuration and TO-126-3 package geometry, enabling direct physical substitution without PCB redesign or mechanical rework.

Compliance Considerations: The BD17910STU is REACH Affected, indicating compliance with current regulatory frameworks. The BD179 is RoHS non-compliant and REACH Unaffected, reflecting its obsolete status.

Temperature Performance: The BD17910STU supports operation to 150°C junction temperature, meeting the upper thermal limit of the BD179 specification.

Frequently Asked Questions (FAQ)

Q: Can the BD17910STU be used as a direct replacement for the BD179 in existing designs?

A: Yes. The BD17910STU is a parametric equivalent with identical electrical ratings and mechanical package configuration. Direct substitution is supported without circuit modification.

Q: Are there any differences in the operating temperature range between these devices?

A: The BD179 specifies -65°C to 150°C junction temperature operation. The BD17910STU supports operation to 150°C. Both devices are compatible for applications within the 0°C to 150°C range. Applications requiring operation below 0°C require verification against the BD17910STU datasheet.

Q: What is the significance of the TO-126-3 package designation?

A: TO-126-3 indicates a three-lead through-hole package with standardized pin configuration and mechanical dimensions. Both the BD179 and BD17910STU use this identical package, ensuring compatibility with existing PCB layouts and socket configurations.

Q: Why is the BD179 classified as obsolete?

A: The BD179 is no longer in active production. The BD17910STU represents the current manufacturing equivalent, providing equivalent performance with ongoing supply availability.

Q: Are there any compliance differences between the BD179 and BD17910STU?

A: The BD17910STU is REACH Affected and complies with current regulatory requirements. The BD179 is RoHS non-compliant and REACH Unaffected, reflecting its obsolete classification. For applications subject to REACH or RoHS compliance requirements, the BD17910STU is the appropriate selection.

Q: What parameters determine substitution eligibility for NPN transistors in this category?

A: Substitution eligibility is determined by equivalence across collector current rating, collector-emitter breakdown voltage, saturation voltage characteristics, collector cutoff current, DC current gain, maximum power dissipation, transition frequency, and package/mounting configuration. All these parameters must match or exceed the original specification.

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