BD179 Equivalent & Substitute Parts

Part Overview

The BD179 is an NPN bipolar junction transistor manufactured by STMicroelectronics, rated for 80 V collector-emitter breakdown voltage and 3 A maximum collector current. The device is packaged in SOT-32 (TO-225AA, TO-126-3) through-hole configuration with a maximum power dissipation of 30 W. The BD179 is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. Substitute parts must maintain electrical compatibility within the specified voltage, current, and power parameters while accommodating through-hole mounting requirements.

Key Parameters

Parameter	BD179 Specification
Transistor Type	NPN
Voltage - Collector Emitter Breakdown (Max)	80 V
Current - Collector (Ic) (Max)	3 A
Power - Max	30 W
Vce Saturation (Max) @ Ib, Ic	800mV @ 100mA, 1A
DC Current Gain (hFE) (Min) @ Ic, Vce	15 @ 2V, 1A
Current - Collector Cutoff (Max)	100µA (ICBO)
Mounting Type	Through Hole
Package / Case	TO-225AA, TO-126-3
Operating Temperature (Max)	150°C (TJ)
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the BD179 is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN (required match)
Voltage - Collector Emitter Breakdown (Max): 80 V (required match)
Mounting Type: Through Hole (required match)
Package / Case: TO-225AA or TO-126-3 (required match)

Secondary Compatibility Parameters:

Current - Collector (Ic) (Max): Must equal or exceed 3 A for direct substitution
Power - Max: Must equal or exceed 30 W for direct substitution
Operating Temperature (Max): Must support 150°C (TJ) or higher
Vce Saturation and DC Current Gain: Application-dependent; lower saturation voltage and higher current gain indicate improved performance characteristics

Substitute parts are grouped into two categories based on current-handling capability:

Category A - Full Current Replacement (Ic ≥ 3 A): Parts capable of handling the full 3 A collector current specification. These include 2N5192G (4 A) and BD441G (4 A).

Category B - Reduced Current Substitution (1 A ≤ Ic < 3 A): Parts with collector current ratings below 3 A but maintaining 80 V breakdown voltage and through-hole packaging. These include 2N4923G (1 A), BD13910S (1.5 A), BD13910STU (1.5 A), BD13916STU (1.5 A), and BD139G (1.5 A). Category B substitutes are applicable only when circuit design permits operation at reduced current levels.

Category C - Intermediate Current Replacement (2 A ≤ Ic < 3 A): Parts with collector current ratings between 2 A and 3 A. This includes BD237G (2 A).

Parameter Comparison

Part Number	Manufacturer	Ic (Max)	Vce Breakdown (Max)	Power (Max)	Vce Sat @ Ib, Ic	hFE (Min) @ Ic, Vce	Package	Status
BD179	STMicroelectronics	3 A	80 V	30 W	800mV @ 100mA, 1A	15 @ 2V, 1A	TO-126-3	Obsolete
2N5192G	onsemi	4 A	80 V	40 W	1.4V @ 1A, 4A	20 @ 1.5A, 2V	TO-126-3	Active
BD441G	onsemi	4 A	80 V	36 W	800mV @ 300mA, 3A	40 @ 500mA, 1V	TO-126-3	Active
BD237G	onsemi	2 A	80 V	25 W	600mV @ 100mA, 1A	25 @ 1A, 2V	TO-126-3	Active
2N4923G	onsemi	1 A	80 V	30 W	600mV @ 100mA, 1A	30 @ 500mA, 1V	TO-126-3	Active
BD139G	onsemi	1.5 A	80 V	12.5 W	500mV @ 50mA, 500mA	40 @ 150mA, 2V	TO-126-3	Active
BD13910S	Fairchild Semiconductor	1.5 A	80 V	1.25 W	500mV @ 50mA, 500mA	63 @ 150mA, 2V	TO-126-3	Active
BD13910STU	onsemi	1.5 A	80 V	1.25 W	500mV @ 50mA, 500mA	63 @ 150mA, 2V	TO-126-3	Active
BD13916STU	onsemi	1.5 A	80 V	1.25 W	500mV @ 50mA, 500mA	100 @ 150mA, 2V	TO-126-3	Active

Engineering Selection Recommendations

Direct Substitution (Full Electrical Compatibility):

BD441G is the primary recommended substitute for BD179 applications. This part maintains 80 V breakdown voltage, supports 4 A collector current (exceeding the 3 A requirement), provides 36 W power dissipation (exceeding the 30 W requirement), and is manufactured by onsemi with active product status. The BD441G exhibits improved saturation voltage characteristics (800mV @ 300mA, 3A) and higher DC current gain (40 @ 500mA, 1V), making it suitable for direct replacement in existing BD179 circuit designs.

2N5192G is an alternative full-current substitute offering 4 A collector current and 40 W power dissipation. This part is manufactured by onsemi with active status and RoHS3 compliance. The 2N5192G exhibits higher saturation voltage (1.4V @ 1A, 4A) compared to BD179, which may affect circuit performance in saturation-mode applications.

Conditional Substitution (Reduced Current Applications):

BD237G is applicable for applications where collector current does not exceed 2 A. This part maintains 80 V breakdown voltage, provides 25 W power dissipation, and is manufactured by onsemi with active status. The BD237G exhibits lower saturation voltage (600mV @ 100mA, 1A) and higher DC current gain (25 @ 1A, 2V) compared to BD179.

BD139G is applicable for applications where collector current does not exceed 1.5 A. This part maintains 80 V breakdown voltage and is manufactured by onsemi with active status. The BD139G provides 12.5 W power dissipation and exhibits improved DC current gain (40 @ 150mA, 2V).

2N4923G is applicable for applications where collector current does not exceed 1 A. This part maintains 80 V breakdown voltage, provides 30 W power dissipation, and is manufactured by onsemi with active status.

Compliance and Certification:

All recommended substitute parts are RoHS3 compliant, REACH unaffected, and classified under ECCN EAR99. All parts maintain through-hole mounting configuration and TO-126-3 package compatibility with the original BD179 specification.

Frequently Asked Questions (FAQ)

Q: Can BD441G directly replace BD179 in all applications?

A: BD441G meets or exceeds all electrical parameters of BD179 (80 V breakdown voltage, 4 A collector current versus 3 A, 36 W power dissipation versus 30 W). Direct substitution is valid for applications operating within BD179 electrical specifications. Circuit performance may improve due to higher current gain and comparable saturation voltage characteristics.

Q: What is the difference between BD13910S, BD13910STU, and BD13916STU?

A: BD13910S is manufactured by Fairchild Semiconductor and supplied in bulk packaging. BD13910STU and BD13916STU are manufactured by onsemi and supplied in tube packaging. All three parts maintain identical electrical specifications (1.5 A, 80 V, 1.25 W) except DC current gain: BD13910S and BD13910STU specify 63 @ 150mA, 2V, while BD13916STU specifies 100 @ 150mA, 2V. Packaging and supplier differences do not affect electrical compatibility.

Q: Why does 2N5192G have higher saturation voltage than BD179?

A: Saturation voltage is a device-specific characteristic determined by semiconductor manufacturing parameters and doping profiles. 2N5192G exhibits 1.4V saturation voltage at 1A, 4A compared to BD179's 800mV at 100mA, 1A. This difference reflects different operating points and device design. Applications sensitive to saturation voltage performance should evaluate 2N5192G in circuit simulation or prototype testing.

Q: Can BD13910S be used in high-current applications?

A: No. BD13910S is rated for maximum 1.5 A collector current and 1.25 W power dissipation. Applications requiring 3 A operation must use BD441G, 2N5192G, or BD237G (2 A maximum).

Q: Are all substitute parts available in the same package as BD179?

A: Yes. All substitute parts listed maintain TO-225AA and TO-126-3 package compatibility, enabling direct physical substitution on printed circuit boards designed for BD179.

Q: What is the significance of product status (Active vs. Obsolete)?

A: Active product status indicates ongoing manufacturing and supplier availability. Obsolete status (BD179) indicates discontinued production. Substitution to active parts (BD441G, 2N5192G, BD237G, BD139G, 2N4923G, BD13910S, BD13910STU, BD13916STU) ensures long-term supply chain continuity and design support.

Q: Do all substitute parts meet RoHS3 compliance?

A: Yes. All substitute parts listed are RoHS3 compliant and REACH unaffected, meeting environmental and regulatory requirements equivalent to BD179.

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