1N6008B Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N6008B is a 22 V, 500 mW Zener diode manufactured by onsemi in DO-35 axial through-hole packaging. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The 1N6008B operates across a temperature range of -65°C to 200°C with ±5% voltage tolerance and is suitable for voltage regulation and protection applications requiring precise 22 V reference levels.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	22	V
Power - Maximum	500	mW
Tolerance	±5	%
Impedance (Maximum)	55	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 17 V	nA
Voltage - Forward (Maximum) @ If	1.2 V @ 200 mA	V
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole
Package / Case	DO-204AH, DO-35, Axial

Substitute Part Grouping Explanation

Substitution of the 1N6008B is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 22 V nominal
Power dissipation: 500 mW maximum
Voltage tolerance: ±5%
Package type: DO-35 (DO-204AH) axial through-hole
Mounting configuration: Through-hole

Secondary Compatibility Factors:

Impedance (Zzt): Maximum 55 Ohms for the 1N6008B; substitute parts with lower impedance values (29 Ohms, 35 Ohms) provide improved regulation characteristics
Reverse leakage current: 100 nA @ 17 V specification
Forward voltage: 1.2 V @ 200 mA reference
Operating temperature range: Minimum -65°C to 200°C required

Substitute parts are grouped into two categories:

Direct Electrical Equivalents (500 mW, 22 V, DO-35): Parts meeting all primary criteria with identical power ratings and package specifications.

Higher Power Alternatives (1 W rating): The 1N4748A offers increased power dissipation (1 W) in a larger DO-41 package, suitable for applications requiring thermal margin but requiring mechanical redesign.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Power (mW)	Tolerance (%)	Zzt (Ohms)	Vf @ 200mA (V)	Temp Range (°C)	Package	Status
1N6008B	onsemi	22	500	±5	55	1.2	-65 to 200	DO-35	Obsolete
1N5251B	Microchip Technology	22	500	±5	29	1.5	-65 to 175	DO-35	Active
1N3526A	Microchip Technology	22	500	±5	35	1.1	-65 to 175	DO-35	Active
1N5251B TR PBFREE	Central Semiconductor Corp	22	500	±5	29	1.1	-65 to 200	DO-35	Active
1N5251B-TAP	Vishay General Semiconductor	22	500	±5	29	1.1	-65 to 175	DO-35	Active
1N5251B-TR	Vishay General Semiconductor	22	500	±5	29	1.1	-65 to 175	DO-35	Active
1N5251BDO35	Microsemi Corporation	22	500	±5	29	1.5	-65 to 175	DO-35	Active
1N5251C-TAP	Vishay General Semiconductor	22	500	±5	29	1.1	-65 to 175	DO-35	Active
1N5541B	Microchip Technology	22	500	±5	108	1.1	-65 to 175	DO-35	Active
1N5744B	Microchip Technology	22	500	±5	55	0.9	-65 to 175	DO-35	Active
1N4748A	Lumimax Optoelectronic Technology	22	1000	±5	23	1.2	-65 to 200	DO-41	Active

Engineering Selection Recommendations

Primary Substitutes (Direct Replacement - DO-35 Package):

The following parts provide direct electrical and mechanical compatibility with the 1N6008B:

1N5251B-TAP (Vishay General Semiconductor) and 1N5251B-TR (Vishay General Semiconductor) are recommended as primary substitutes. Both parts are AEC-Q101 qualified automotive-grade components with ROHS3 compliance. These parts feature lower impedance (29 Ohms versus 55 Ohms), providing superior voltage regulation characteristics. Operating temperature range extends to 175°C, which is acceptable for most applications previously using the 1N6008B. Both are available in cut-tape packaging with active product status.

1N5251B TR PBFREE (Central Semiconductor Corp) offers identical electrical specifications to the Vishay variants with extended operating temperature range to 200°C, matching the original 1N6008B thermal envelope. This part carries ROHS3 compliance and is available in cut-tape packaging.

1N3526A (Microchip Technology) provides active product status with 500 mW power rating and DO-35 packaging. Impedance of 35 Ohms falls between the original 1N6008B and lower-impedance alternatives, offering a balanced regulation profile. Operating temperature range is -65°C to 175°C.

1N5744B (Microchip Technology) matches the original 1N6008B impedance specification (55 Ohms) and maintains identical electrical characteristics. This part is suitable for applications requiring impedance matching to the original design.

Secondary Substitutes (Thermal Margin Enhancement):

1N4748A (Lumimax Optoelectronic Technology) provides 1 W power dissipation in DO-41 package, offering increased thermal capacity. This part is suitable for applications requiring additional power margin or thermal headroom. Mechanical redesign is required due to package change from DO-35 to DO-41. Operating temperature range extends to 200°C. RoHS compliance is confirmed.

Compliance Considerations:

Parts with ROHS3 compliance (1N5251B-TAP, 1N5251B-TR, 1N5251B TR PBFREE, 1N5251BDO35, 1N5251C-TAP) are preferred for new designs and applications subject to RoHS regulations. Parts with RoHS non-compliant status (1N3526A, 1N5541B, 1N5744B) remain suitable for legacy system support and applications not subject to RoHS requirements.

All substitute parts carry REACH Unaffected status and EAR99 export classification, matching the original 1N6008B regulatory profile.

Frequently Asked Questions (FAQ)

Q: Can the 1N5251B-TAP directly replace the 1N6008B without circuit modification?

A: Yes. The 1N5251B-TAP provides identical zener voltage (22 V), power rating (500 mW), tolerance (±5%), and DO-35 package configuration. Lower impedance (29 Ohms versus 55 Ohms) improves voltage regulation but does not prevent direct substitution. No circuit modification is required.

Q: What is the significance of impedance differences between substitute parts?

A: Impedance (Zzt) affects dynamic regulation characteristics. Lower impedance values (29 Ohms in 1N5251B variants) provide better voltage stability under load transients. Higher impedance values (55 Ohms in 1N5744B, 108 Ohms in 1N5541B) result in greater voltage variation with current changes. Selection depends on circuit regulation requirements.

Q: Why do some substitutes have operating temperature ranges limited to 175°C instead of 200°C?

A: Operating temperature range reflects manufacturer specifications and thermal design margins. Parts rated to 175°C remain suitable for applications operating within that range. For applications requiring full -65°C to 200°C operation, select 1N5251B TR PBFREE or 1N4748A.

Q: Is the 1N4748A (1 W, DO-41) suitable as a substitute?

A: The 1N4748A provides identical zener voltage and tolerance with increased power dissipation (1 W versus 500 mW). The DO-41 package is physically larger than DO-35, requiring mechanical redesign of the circuit board layout and component mounting. This part is suitable for applications requiring thermal margin or higher power dissipation.

Q: What packaging options are available for substitute parts?

A: Most substitutes are available in DO-35 package in multiple packaging formats: bulk (loose components), cut-tape (CT), and tape & box (TB). Packaging selection affects procurement and assembly processes but does not alter electrical performance. The 1N4748A is available only in DO-41 package.

Q: Are automotive-qualified parts (AEC-Q101) required for my application?

A: AEC-Q101 qualification is required for automotive applications and applications subject to automotive supply chain requirements. The 1N5251B-TAP and 1N5251B-TR carry AEC-Q101 qualification. For non-automotive applications, non-qualified parts remain suitable.

Q: What is the difference between 1N5251B, 1N5251B-TAP, and 1N5251B-TR?

A: These part numbers represent the same electrical component in different packaging formats. 1N5251B is the base part number. The suffix indicates packaging: -TAP denotes cut-tape packaging, -TR denotes tape reel. Electrical specifications are identical; packaging selection depends on procurement and assembly requirements.

Q: Can I use 1N5251BDO35 as a substitute?

A: Yes. The 1N5251BDO35 provides identical electrical specifications (22 V, 500 mW, ±5% tolerance, DO-35 package) with active product status and ROHS3 compliance. Forward voltage specification is 1.5 V @ 200 mA, which is within acceptable variation for zener diode applications.

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