BZX79C22 A0G Equivalent & Substitute Parts

Part Overview

The BZX79C22 A0G is an active-status zener diode manufactured by Taiwan Semiconductor Corporation, rated for 22 V nominal zener voltage with 500 mW maximum power dissipation. This component operates across a temperature range of -65°C to 175°C and is packaged in the DO-35 (DO-204AH) axial through-hole configuration. The device is RoHS3 compliant and REACH unaffected, making it suitable for modern electronic applications requiring voltage regulation and transient protection in circuits where 22 V zener reference voltage is specified.

Equivalent and substitute parts are identified based on matching critical electrical parameters: nominal zener voltage (22 V), power rating (500 mW), tolerance (±5%), package type (DO-35), and mounting configuration (through-hole). Substitutes must maintain functional compatibility within the specified operating temperature range and forward/reverse electrical characteristics.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	22	V
Tolerance	±5	%
Power - Max	500	mW
Package / Case	DO-35 (DO-204AH)	Axial
Mounting Type	Through Hole	—
Operating Temperature Range	-65°C to 175°C	TJ

Substitute Part Grouping Explanation

Substitution eligibility for the BZX79C22 A0G is determined by the following critical parameters:

Primary Matching Criteria:

Nominal zener voltage: 22 V
Maximum power dissipation: 500 mW
Voltage tolerance: ±5%
Package type: DO-35 (DO-204AH) axial configuration
Mounting type: Through-hole

Secondary Compatibility Factors:

Operating temperature range (minimum -65°C, maximum ≥175°C)
Forward voltage characteristics (Vf @ If)
Reverse leakage current specifications
Dynamic impedance (Zzt)

The substitute parts 1N5251B and 1N5251BTR meet the primary matching criteria across all critical electrical and mechanical parameters. Both devices are rated for 22 V zener voltage, 500 mW power dissipation, ±5% tolerance, and are packaged in DO-35 through-hole configuration. Variations in secondary parameters such as impedance, reverse leakage current, and forward voltage are within acceptable ranges for functional equivalence in standard voltage regulation and protection applications.

Parameter Comparison

Parameter	BZX79C22 A0G	1N5251B	1N5251BTR
Manufacturer	Taiwan Semiconductor Corporation	Microchip Technology	Fairchild Semiconductor
Voltage - Zener (Nom)	22 V	22 V	22 V
Tolerance	±5%	±5%	±5%
Power - Max	500 mW	500 mW	500 mW
Impedance (Max) (Zzt)	55 Ohms	29 Ohms	29 Ohms
Current - Reverse Leakage @ Vr	50 nA @ 15.4 V	100 nA @ 17 V	100 nA @ 17 V
Voltage - Forward (Vf) (Max) @ If	1.5 V @ 100 mA	1.5 V @ 200 mA	1.2 V @ 200 mA
Operating Temperature	-65°C ~ 175°C	-65°C ~ 175°C	-65°C ~ 200°C
Package / Case	DO-35 (DO-204AH)	DO-35 (DO-204AH)	DO-35 (DO-204AH)
Mounting Type	Through Hole	Through Hole	Through Hole
RoHS Status	RoHS3 Compliant	RoHS non-compliant	Not specified
Product Status	Active	Active	Active

Engineering Selection Recommendations

BZX79C22 A0G (Primary Component)

The BZX79C22 A0G is the specified component and remains the preferred selection when RoHS3 compliance is a mandatory requirement. This device is actively manufactured and maintains full compliance with RoHS3 and REACH regulations. Current inventory of 849 pieces supports immediate procurement for production applications.

1N5251BTR (Preferred Substitute)

The 1N5251BTR manufactured by Fairchild Semiconductor is the primary substitute option. This device matches all critical electrical parameters (22 V zener voltage, 500 mW power rating, ±5% tolerance) and package specifications (DO-35 through-hole). The extended operating temperature range (-65°C to 200°C) provides additional thermal margin beyond the primary component. Dynamic impedance of 29 Ohms is lower than the primary part, resulting in improved voltage regulation stability. Forward voltage characteristics (1.2 V @ 200 mA) are superior to the primary component. High inventory availability (7084 pieces) ensures supply continuity. Compliance status for RoHS and REACH is not specified; verification against project-specific regulatory requirements is necessary.

1N5251B (Secondary Substitute)

The 1N5251B manufactured by Microchip Technology is a secondary substitute option. This device meets all primary matching criteria with identical zener voltage, power rating, tolerance, and package configuration. Operating temperature range matches the primary component (-65°C to 175°C). Dynamic impedance (29 Ohms) and reverse leakage characteristics are equivalent to the 1N5251BTR. However, this part is RoHS non-compliant, restricting its use in applications subject to RoHS regulations. Inventory availability (2103 pieces) is adequate for standard procurement. Selection of this substitute is limited to applications where RoHS compliance is not required.

Frequently Asked Questions (FAQ)

Q: What are the critical parameters that determine if a zener diode can substitute for the BZX79C22 A0G?

A: The critical parameters are nominal zener voltage (22 V), maximum power dissipation (500 mW), voltage tolerance (±5%), package type (DO-35 axial), and mounting configuration (through-hole). All substitute parts must match these specifications exactly to ensure functional compatibility in the circuit.

Q: Can the 1N5251BTR be used in place of the BZX79C22 A0G without circuit modification?

A: Yes. The 1N5251BTR matches all critical electrical and mechanical parameters. The lower dynamic impedance (29 Ohms versus 55 Ohms) and extended temperature range provide equivalent or improved performance. No circuit modifications are required for direct substitution.

Q: What is the difference between the 1N5251B and 1N5251BTR?

A: Both devices have identical electrical specifications (22 V zener voltage, 500 mW power rating, ±5% tolerance, DO-35 package). The primary difference is RoHS compliance status: 1N5251BTR compliance is not specified, while 1N5251B is explicitly RoHS non-compliant. Selection depends on regulatory requirements for the application.

Q: Is the BZX79C22 A0G RoHS compliant?

A: Yes. The BZX79C22 A0G is RoHS3 compliant and REACH unaffected, making it suitable for applications subject to European environmental regulations.

Q: Can I use the 1N5251B in a RoHS-regulated application?

A: No. The 1N5251B is explicitly RoHS non-compliant and cannot be used in applications requiring RoHS compliance. The 1N5251BTR is the appropriate substitute for RoHS-regulated designs.

Q: What is the operating temperature range for each part?

A: The BZX79C22 A0G and 1N5251B operate from -65°C to 175°C. The 1N5251BTR extends this range to -65°C to 200°C, providing additional thermal margin in high-temperature applications.

Q: Are there any differences in forward voltage characteristics between the substitute parts?

A: Yes. The BZX79C22 A0G specifies 1.5 V @ 100 mA. The 1N5251B specifies 1.5 V @ 200 mA. The 1N5251BTR specifies 1.2 V @ 200 mA, indicating superior forward voltage performance. These differences are within acceptable ranges for standard voltage regulation applications.

Q: What is the significance of dynamic impedance (Zzt) differences?

A: Dynamic impedance affects voltage regulation stability. The BZX79C22 A0G has 55 Ohms maximum impedance, while both substitute parts have 29 Ohms. Lower impedance provides better voltage regulation and reduced output impedance, resulting in improved circuit performance.

Q: Can I substitute parts based on package appearance alone?

A: No. While all three parts use the DO-35 axial package, electrical parameters must match exactly. Package compatibility is necessary but not sufficient for substitution. Verify zener voltage, power rating, tolerance, and temperature range before selecting a substitute.

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