BZX55A20-TAP Equivalent & Substitute Parts

Part Overview

The BZX55A20-TAP is a 20 V, 500 mW Zener diode manufactured by Vishay General Semiconductor - Diodes Division in a DO-35 through-hole package. This component is classified as obsolete, though 926 pieces remain in stock. The part carries automotive-grade qualification (AEC-Q101) and is ROHS3 compliant.

Due to the obsolete status of the BZX55A20-TAP, equivalent and substitute parts are necessary to ensure continued design support, procurement availability, and long-term supply chain reliability. Active alternatives with identical or compatible electrical and mechanical specifications are available from multiple manufacturers.

Key Parameters

Parameter	BZX55A20-TAP Value
Voltage - Zener (Nom)	20 V
Power - Max	500 mW
Tolerance	±1%
Impedance (Max)	55 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 15 V
Voltage - Forward (Vf) (Max) @ If	1.5 V @ 200 mA
Operating Temperature	175°C
Package / Case	DO-204AH (DO-35), Axial
Mounting Type	Through Hole
Grade	Automotive
Qualification	AEC-Q101

Substitute Part Grouping Explanation

Substitution of the BZX55A20-TAP is determined by the following critical parameters:

Electrical Compatibility Requirements:

Zener voltage: 20 V nominal
Power dissipation: 500 mW maximum
Package type: DO-35 (DO-204AH) through-hole axial configuration
Mounting: Through-hole only

Tolerance Considerations: The BZX55A20-TAP specifies ±1% tolerance. Substitute parts with wider tolerances (±2%, ±5%, ±10%) remain functionally compatible in applications where the tighter tolerance is not a design-critical requirement. However, tolerance degradation should be evaluated against circuit specifications.

Impedance and Leakage Parameters: Impedance values ranging from 25 to 62 Ohms and reverse leakage currents at 100 nA are acceptable within the DO-35 package class for 20 V, 500 mW Zener diodes.

Temperature Range: The BZX55A20-TAP specifies a maximum operating temperature of 175°C. Substitute parts with extended temperature ranges (-65°C to 175°C or -65°C to 200°C) provide equal or superior thermal performance.

Compliance and Qualification: Automotive-grade parts with AEC-Q101 qualification are preferred for direct replacement. Military-grade alternatives (MIL-PRF-19500/435) provide enhanced reliability but are not required for automotive applications.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Vf (Max) @ If	Operating Temp	Package	Status	Grade
BZX55A20-TAP	Vishay	20 V	±1%	500 mW	55 Ω	1.5 V @ 200 mA	175°C	DO-35	Obsolete	Automotive
BZX55B20-TAP	Vishay	20 V	±2%	500 mW	55 Ω	1.5 V @ 200 mA	-65°C ~ 175°C	DO-35	Active	Automotive
1N5250B	Microchip	20 V	±5%	500 mW	25 Ω	1.5 V @ 200 mA	-65°C ~ 175°C	DO-35	Active	Commercial
1N5250BTR	Fairchild	20 V	±5%	500 mW	25 Ω	1.2 V @ 200 mA	-65°C ~ 200°C	DO-35	Active	Commercial
1N5743B	Microchip	20 V	±5%	500 mW	55 Ω	900 mV @ 10 mA	-65°C ~ 175°C	DO-35	Active	Commercial
1N6007A	Microchip	20 V	±10%	500 mW	62 Ω	1.1 V @ 200 mA	-65°C ~ 175°C	DO-35	Active	Commercial
1N6007B	Microchip	20 V	±5%	500 mW	48 Ω	1.1 V @ 200 mA	-65°C ~ 175°C	DO-35	Active	Commercial
JAN1N4114-1	Microchip	20 V	±5%	Not specified	150 Ω	1.1 V @ 200 mA	-65°C ~ 175°C	DO-35	Active	Military

Engineering Selection Recommendations

Primary Recommendation: BZX55B20-TAP

The BZX55B20-TAP is the direct successor to the BZX55A20-TAP. Both parts are manufactured by Vishay and share identical electrical specifications except for tolerance (±2% versus ±1%) and operating temperature range. The BZX55B20-TAP is active in production with 25,100 units in stock, ensuring long-term availability. It maintains automotive-grade qualification (AEC-Q101) and ROHS3 compliance. The tolerance difference of ±1% is acceptable in most circuit applications where the original ±1% specification was not a critical design constraint.

Secondary Recommendation: 1N5743B

The 1N5743B from Microchip Technology provides an active alternative with identical impedance (55 Ω) to the original part. It maintains the 20 V nominal voltage and 500 mW power rating. The ±5% tolerance represents a wider specification window. This part is active with 1,067 units in stock and operates across the -65°C to 175°C temperature range.

Alternative Recommendation: 1N5250BTR

The 1N5250BTR from Fairchild Semiconductor is an active part with extended operating temperature range (-65°C to 200°C). It provides the lowest impedance (25 Ω) among available substitutes and the lowest forward voltage (1.2 V @ 200 mA). With 20,200 units in stock, this part offers superior availability. The ±5% tolerance and commercial-grade classification are suitable for non-automotive applications.

Military-Grade Alternative: JAN1N4114-1

The JAN1N4114-1 from Microchip Technology is qualified to MIL-PRF-19500/435 and carries military-grade classification. This part is appropriate for applications requiring enhanced reliability and traceability. However, power dissipation is not specified in the provided data, requiring verification before selection for 500 mW applications.

Not Recommended for Direct Replacement:

The 1N6007A and 1N6007B exhibit wider impedance specifications (62 Ω and 48 Ω respectively) and should be evaluated only when impedance tolerance is not a design constraint.

Frequently Asked Questions (FAQ)

Q: Can I use BZX55B20-TAP as a direct replacement for BZX55A20-TAP?

A: Yes. The BZX55B20-TAP is the active production equivalent. Both parts share identical zener voltage (20 V), power rating (500 mW), impedance (55 Ω), and package (DO-35). The tolerance difference (±2% versus ±1%) and extended operating temperature range of the BZX55B20-TAP are compatible with the original specification.

Q: What is the difference between impedance values in the substitute parts?

A: Impedance (Zzt) affects the dynamic resistance of the Zener diode at operating current. The BZX55A20-TAP and BZX55B20-TAP specify 55 Ω, while alternatives range from 25 Ω to 150 Ω. Lower impedance provides better voltage regulation at varying currents. Selection depends on circuit requirements for voltage stability and load regulation.

Q: Are all substitute parts automotive-qualified?

A: No. Only BZX55B20-TAP carries automotive-grade qualification (AEC-Q101). The 1N5250B, 1N5250BTR, 1N5743B, 1N6007A, and 1N6007B are commercial-grade parts. The JAN1N4114-1 is military-grade. Automotive applications should prioritize BZX55B20-TAP unless design specifications permit commercial-grade alternatives.

Q: Can I use parts with ±5% or ±10% tolerance instead of ±1%?

A: Tolerance selection depends on circuit design requirements. If the original ±1% specification was chosen for voltage regulation precision, wider tolerances may affect circuit performance. If the ±1% tolerance was specified conservatively, ±5% alternatives are functionally compatible. Circuit analysis is required to determine acceptable tolerance ranges.

Q: Do all substitute parts use the same DO-35 package?

A: Yes. All listed substitute parts use the DO-35 (DO-204AH) through-hole axial package. Physical dimensions and PCB footprints are identical, enabling direct mechanical replacement without layout modifications.

Q: What is the significance of the operating temperature range difference?

A: The BZX55A20-TAP specifies a maximum operating temperature of 175°C. Substitute parts with extended ranges (-65°C to 175°C or -65°C to 200°C) provide equal or superior thermal performance. Extended ranges do not degrade performance at the original 175°C maximum; they simply allow operation at lower temperatures and, in some cases, higher temperatures.

Q: Is RoHS compliance important for my application?

A: The BZX55A20-TAP is ROHS3 compliant. Most substitute parts (BZX55B20-TAP) maintain this compliance. However, 1N5250B, 1N5743B, 1N6007A, 1N6007B, and JAN1N4114-1 are listed as RoHS non-compliant. If RoHS compliance is a design requirement, BZX55B20-TAP is the only active substitute that maintains this certification.

Q: What does "Bulk" packaging mean versus "Cut Tape"?

A: Cut Tape (CT) packaging, used for BZX55B20-TAP, provides components on continuous tape suitable for automated pick-and-place assembly. Bulk packaging indicates loose components or alternative tape formats. For high-volume manufacturing, Cut Tape is preferred. For prototyping or low-volume applications, either format is acceptable.

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