BZX55F12-TR Equivalent & Substitute Parts

Part Overview

The BZX55F12-TR is a 12 V, 500 mW Zener diode manufactured by Vishay General Semiconductor - Diodes Division in a through-hole DO-35 package. This component is classified as obsolete, though 962 pieces remain in stock as new original inventory. The part meets automotive-grade specifications with AEC-Q101 qualification and is RoHS3 compliant.

Due to the obsolete product status of the BZX55F12-TR, identifying equivalent and substitute parts is necessary to ensure design continuity and supply chain reliability. Substitute components must maintain electrical compatibility across voltage regulation, power dissipation, and thermal operating ranges while accommodating packaging and tolerance variations.

Key Parameters

Parameter	BZX55F12-TR Value	Unit
Voltage - Zener (Nominal)	12	V
Tolerance	±1%	—
Power - Maximum	500	mW
Impedance (Maximum)	20	Ohms
Current - Reverse Leakage @ Vr	100	nA @ 9.1 V
Voltage - Forward (Maximum) @ If	1.5	V @ 200 mA
Operating Temperature	175	°C
Mounting Type	Through Hole	—
Package / Case	DO-204AH, DO-35, Axial	—
Grade	Automotive	—
Qualification	AEC-Q101	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the BZX55F12-TR is determined by the following critical parameters:

Electrical Compatibility Requirements:

Zener voltage must be 12 V nominal
Power dissipation rating must be 500 mW or greater
Mounting type must be through-hole
Package must be DO-35 or DO-204AH (equivalent)

Tolerance Considerations: The BZX55F12-TR specifies ±1% tolerance. Substitute parts with ±2% or ±5% tolerance represent relaxed specifications and are acceptable for applications where tighter voltage regulation is not critical. Parts with ±1% tolerance provide equivalent precision.

Thermal and Operating Range: The BZX55F12-TR operates to 175°C maximum. Substitute parts with extended operating ranges (−65°C to 200°C) provide enhanced thermal margin and are directly compatible.

Compliance and Status: Active product status indicates ongoing availability. RoHS3 compliance is preferred for new designs. Automotive-grade qualification (AEC-Q101) is maintained across all recommended substitutes.

Impedance and Leakage: Impedance values between 10 and 30 Ohms are acceptable within the 12 V, 500 mW classification. Reverse leakage current specifications vary but remain within acceptable limits for voltage regulation applications.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Vf @ 200mA (V)	Temp Range (°C)	Status	RoHS
BZX55F12-TR	Vishay	12	±1%	500	20	1.5	to 175	Obsolete	ROHS3
BZX55B12-TR	Vishay	12	±2%	500	20	1.5	−65 to 175	Active	ROHS3
1N3520A	Microchip	12	±5%	500	10	1.1	−65 to 175	Active	Non-compliant
1N5242B BK PBFREE	Central Semiconductor	12	±5%	500	30	1.1	−65 to 200	Active	ROHS3
1N5242B TR PBFREE	Central Semiconductor	12	±5%	500	30	1.1	−65 to 200	Active	ROHS3
1N5242BDO35	Microsemi	12	±5%	500	30	1.5	−65 to 175	Active	ROHS3
1N5738C	Microchip	12	±1%	500	25	0.9	−65 to 175	Active	Non-compliant
1N6002B	Microchip	12	±5%	500	22	1.1	−65 to 175	Active	Non-compliant
1N6002C	Microchip	12	±2%	500	22	1.1	−65 to 175	Active	Non-compliant
1N759A BK PBFREE	Central Semiconductor	12	±5%	500	30	1.5	−65 to 200	Active	ROHS3
1N759A TR PBFREE	Central Semiconductor	12	±5%	500	30	1.5	−65 to 200	Active	ROHS3

Engineering Selection Recommendations

Primary Recommendation: BZX55B12-TR

The BZX55B12-TR is the direct successor from Vishay General Semiconductor - Diodes Division. It maintains the same manufacturer lineage, identical power rating (500 mW), and equivalent impedance (20 Ohms). The tolerance relaxation from ±1% to ±2% is acceptable for most voltage regulation applications. This part is active, RoHS3 compliant, and carries AEC-Q101 automotive qualification. The extended operating temperature range (−65°C to 175°C) provides improved thermal margin compared to the BZX55F12-TR.

Secondary Recommendations: 1N5242B Series (Central Semiconductor)

The 1N5242B TR PBFREE and 1N5242B BK PBFREE variants are active, RoHS3 compliant parts with extended operating temperature to 200°C. Both maintain 12 V nominal voltage and 500 mW power rating. The ±5% tolerance and 30 Ohm impedance are suitable for general voltage regulation. The TR (cut tape) packaging offers 3,186 pieces in stock; the BK (bulk) packaging offers 865 pieces. These parts are lead-free and PBFREE qualified.

Tertiary Recommendations: 1N759A Series (Central Semiconductor)

The 1N759A TR PBFREE and 1N759A BK PBFREE are active, RoHS3 compliant alternatives with the highest inventory availability (20,969 and 12,748 pieces respectively). Both provide 12 V nominal voltage, 500 mW power, and extended operating temperature to 200°C. The ±5% tolerance and 30 Ohm impedance are acceptable for standard applications. Lead-free qualification is confirmed.

Alternative Options: 1N5738C and 1N6002C

The 1N5738C (Microchip) matches the ±1% tolerance of the BZX55F12-TR and provides 12 V, 500 mW operation with 984 pieces in stock. However, RoHS compliance is non-compliant. The 1N6002C (Microchip) offers ±2% tolerance with 897 pieces in stock but also carries non-compliant RoHS status. Both are suitable for applications where RoHS compliance is not required.

Compliance Considerations:

For new designs requiring RoHS3 compliance and automotive qualification, select from: BZX55B12-TR, 1N5242B TR PBFREE, 1N5242B BK PBFREE, 1N5242BDO35, 1N759A BK PBFREE, or 1N759A TR PBFREE.

For applications where RoHS compliance is not mandatory, 1N5738C and 1N6002C provide additional options with tighter tolerance specifications.

Frequently Asked Questions (FAQ)

Q: Can the BZX55B12-TR directly replace the BZX55F12-TR?

A: Yes. The BZX55B12-TR is the active equivalent from the same manufacturer (Vishay). Both parts share identical 12 V nominal voltage, 500 mW power rating, 20 Ohm impedance, and DO-35 packaging. The tolerance changes from ±1% to ±2%, which is acceptable for most voltage regulation circuits. The BZX55B12-TR is active and RoHS3 compliant, addressing the obsolete status of the BZX55F12-TR.

Q: What is the difference between the 1N5242B TR PBFREE and 1N5242B BK PBFREE?

A: Both parts are electrically identical with 12 V nominal voltage, 500 mW power, and ±5% tolerance. The difference is packaging: TR denotes cut tape (3,186 pieces available), while BK denotes bulk packaging (865 pieces available). Selection depends on procurement quantity and handling requirements. Both are RoHS3 compliant and lead-free.

Q: Why do some substitutes have ±5% tolerance instead of ±1%?

A: The BZX55F12-TR specifies ±1% tolerance for precise voltage regulation. Substitute parts with ±5% tolerance (1N3520A, 1N5242B series, 1N759A series, 1N6002B) represent relaxed specifications. These are acceptable when the application circuit can tolerate wider voltage variation. For applications requiring ±1% precision, select 1N5738C or 1N6002C.

Q: Are all substitute parts automotive-grade?

A: The BZX55F12-TR carries automotive-grade classification with AEC-Q101 qualification. Among substitutes, only BZX55B12-TR explicitly maintains automotive-grade status with AEC-Q101. Other substitutes (1N5242B series, 1N759A series, 1N5738C, 1N6002B, 1N6002C, 1N3520A) do not list automotive qualification in the provided specifications. For automotive applications, BZX55B12-TR is the recommended choice.

Q: What is the maximum operating temperature for each substitute?

A: BZX55F12-TR operates to 175°C. BZX55B12-TR, 1N3520A, 1N5242BDO35, 1N5738C, 1N6002B, and 1N6002C operate to 175°C. The 1N5242B TR PBFREE, 1N5242B BK PBFREE, 1N759A BK PBFREE, and 1N759A TR PBFREE extend to 200°C, providing additional thermal margin.

Q: Which substitute has the best inventory availability?

A: The 1N759A TR PBFREE has the highest inventory with 20,969 pieces in stock, followed by 1N759A BK PBFREE with 12,748 pieces. Both are active, RoHS3 compliant, and suitable for general 12 V, 500 mW applications. The BZX55B12-TR offers 24,356 pieces, making it the most readily available direct equivalent.

Q: Can I use a substitute with lower impedance (Zzt)?

A: Yes. The BZX55F12-TR specifies 20 Ohm maximum impedance. Substitutes with lower impedance (1N3520A at 10 Ohms) provide tighter voltage regulation and are directly compatible. Lower impedance does not create compatibility issues; it represents improved performance characteristics.

Q: What does "PBFREE" designation mean?

A: PBFREE indicates lead-free construction, compliant with RoHS directives. Parts designated 1N759A TR PBFREE, 1N759A BK PBFREE, 1N5242B TR PBFREE, and 1N5242B BK PBFREE are lead-free and suitable for applications requiring environmental compliance.

Q: Is the DO-35 package identical across all substitutes?

A: Yes. All substitute parts use the DO-35 package (also designated DO-204AH or axial configuration). The physical dimensions and pin configuration are standardized, allowing direct mechanical substitution in through-hole PCB designs.

Q: Which substitute should I choose for a new design?

A: For new designs, select BZX55B12-TR (direct Vishay equivalent, active status, RoHS3 compliant) or 1N759A TR PBFREE (highest inventory, extended temperature range, lead-free). Both are active, widely available, and meet modern compliance requirements. If automotive qualification is required, BZX55B12-TR is the only option with AEC-Q101 certification.

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