BD1406S Equivalent & Substitute Parts

Part Overview

The BD1406S is a PNP bipolar junction transistor manufactured by onsemi, rated for 80 V collector-emitter breakdown voltage and 1.5 A maximum collector current in a TO-126-3 through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The BD1406S serves in general-purpose switching and amplification applications requiring moderate current handling and voltage ratings.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Collector Current (Max)	1.5	A
Collector-Emitter Breakdown Voltage (Max)	80	V
Power Dissipation (Max)	1.25	W
Vce Saturation (Max)	500	mV @ 50mA, 500mA
DC Current Gain (hFE Min)	40	@ 150mA, 2V
Collector Cutoff Current (Max)	100	nA
Operating Temperature (Max)	150	°C
Mounting Type	Through Hole	—
Package	TO-126-3	—

Substitute Part Grouping Explanation

Substitution of the BD1406S is determined by electrical parameter equivalence and package compatibility. The critical parameters governing substitution are:

Electrical Equivalence Criteria:

Transistor polarity (PNP)
Collector current rating (1.5 A minimum)
Collector-emitter breakdown voltage (80 V minimum)
Power dissipation capability (1.25 W minimum)
DC current gain (hFE ≥ 40 at specified conditions)
Vce saturation characteristics (500 mV maximum at rated conditions)

Package Compatibility:

Through-hole mounting requirement
TO-126-3 or equivalent footprint compatibility

Substitute parts are classified into two categories:

Direct Substitutes: Parts meeting all electrical parameters and package requirements with identical or superior ratings.

Similar Substitutes: Parts with equivalent electrical performance but with variations in secondary parameters such as maximum power dissipation, frequency response, or operating temperature range. These require circuit-level verification for specific applications.

Parameter Comparison

Part Number	Manufacturer	Ic (Max) [A]	Vce(br) [V]	Power [W]	hFE (Min)	Vce Sat [mV]	Package	Status
BD1406S	onsemi	1.5	80	1.25	40	500	TO-126-3	Obsolete
BD14016S	onsemi	1.5	80	1.25	40	500	TO-126-3	Last Time Buy
BD140G	onsemi	1.5	80	1.25	40	500	TO-126-3	Active
BD14016STU	onsemi	1.5	80	1.25	100	500	TO-126-3	Last Time Buy
BD140	STMicroelectronics	1.5	80	1.25	40	500	SOT-32-3	Active
BD140-16	STMicroelectronics	1.5	80	1.25	40	500	SOT-32	Active
2N4920G	onsemi	1.0	80	30	30	600	TO-126	Active
BD180G	onsemi	1.0	80	30	40	800	TO-126	Active

Engineering Selection Recommendations

Primary Recommendation: BD140G (onsemi)

The BD140G is the preferred direct substitute for the BD1406S. This part maintains identical electrical specifications across all critical parameters: 1.5 A collector current, 80 V breakdown voltage, 1.25 W power dissipation, and 40 minimum hFE. The BD140G is in active production status, ensuring long-term availability. The part carries RoHS3 compliance and REACH unaffected status, meeting current regulatory requirements. The TO-126-3 package provides direct footprint compatibility.

Secondary Recommendation: BD14016S (onsemi)

The BD14016S provides electrical equivalence to the BD1406S with identical ratings across all parameters. However, this part is classified as Last Time Buy, indicating limited future availability. Selection of this part should be reserved for applications where existing inventory must be maintained or where BD140G availability is constrained.

Alternative Recommendation: BD14016STU (onsemi)

The BD14016STU offers superior DC current gain (hFE minimum of 100 versus 40), providing enhanced amplification characteristics. This part is supplied in tube packaging and carries Last Time Buy status. The elevated hFE may benefit circuits requiring higher gain, but circuit redesign verification is necessary to confirm compatibility with existing designs.

Cross-Manufacturer Option: BD140 or BD140-16 (STMicroelectronics)

STMicroelectronics BD140 and BD140-16 devices provide electrical equivalence with active production status and RoHS3 compliance. These parts differ in package designation (SOT-32-3 and SOT-32 respectively) compared to the TO-126-3 specification. Footprint verification is required before selection, as package outline differences may affect PCB layout compatibility despite functional equivalence.

Not Recommended for Direct Substitution: 2N4920G and BD180G

The 2N4920G and BD180G are classified as similar substitutes due to reduced maximum collector current (1.0 A versus 1.5 A). These parts are suitable only for applications where the circuit design accommodates the lower current rating. The 2N4920G exhibits lower hFE (30 minimum) and higher Vce saturation (600 mV), while BD180G shows elevated Vce saturation (800 mV). Selection of these parts requires circuit-level analysis to confirm functional compatibility.

Frequently Asked Questions (FAQ)

Q: Can BD140G be used as a direct replacement for BD1406S without circuit modification?

A: Yes. The BD140G maintains identical electrical specifications for collector current (1.5 A), breakdown voltage (80 V), power dissipation (1.25 W), and DC current gain (40 minimum). The TO-126-3 package provides direct footprint compatibility. No circuit modification is required.

Q: What is the difference between BD14016S and BD140G?

A: Both parts are electrically identical with 1.5 A collector current, 80 V breakdown voltage, and 40 minimum hFE. The primary difference is product status: BD14016S is Last Time Buy (limited availability), while BD140G is in active production. For new designs, BD140G is preferred due to long-term availability assurance.

Q: Why is BD14016STU listed as a similar substitute rather than a direct substitute?

A: While BD14016STU meets all electrical requirements, it features a higher minimum DC current gain (hFE of 100 versus 40). This elevated gain may alter circuit behavior in applications sensitive to transistor gain characteristics. Verification of circuit performance with the higher gain specification is necessary before selection.

Q: Can STMicroelectronics BD140 replace the onsemi BD1406S?

A: Electrical substitution is valid; however, the BD140 is specified in SOT-32-3 package while the BD1406S uses TO-126-3. Although both are through-hole packages, the physical dimensions and pin spacing differ. PCB layout compatibility must be verified before selection. If the PCB footprint accommodates SOT-32-3, the part is suitable.

Q: Are 2N4920G and BD180G suitable replacements?

A: These parts are not recommended for direct substitution. Both are rated for 1.0 A maximum collector current, which is 33% lower than the BD1406S specification of 1.5 A. Selection is appropriate only if the circuit design operates at or below 1.0 A collector current. Additional parameter variations (hFE and Vce saturation) require circuit-level verification.

Q: What compliance certifications should I verify for new designs?

A: All recommended substitute parts carry RoHS3 compliance and REACH unaffected status. These certifications meet current regulatory requirements for electronic component procurement in most jurisdictions. Verify specific compliance requirements for your application and region.

Q: Does package type affect electrical performance?

A: No. Package type (TO-126-3, SOT-32-3, or TO-126) does not affect electrical performance. Package selection is determined by PCB layout requirements and mechanical constraints. Electrical specifications remain consistent across equivalent package variants of the same part family.

Q: What is the significance of "Last Time Buy" status?

A: Last Time Buy indicates that the manufacturer will discontinue production after a specified date. Parts with this status have limited remaining availability. For long-term production requirements, selection of parts in active production status (such as BD140G) is recommended to ensure supply continuity.

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