1N5643A Transient Voltage Suppressor Equivalent & Substitute Parts

Part Overview

The 1N5643A is a unidirectional Zener transient voltage suppressor (TVS) diode manufactured by Microchip Technology, designed for general-purpose overvoltage protection applications. This component features a 23.1V reverse standoff voltage with a 37.5V maximum clamping voltage and 40A peak pulse current capability in a through-hole DO-13 package. The 1N5643A is discontinued at DiGi Electronics, necessitating identification of functionally equivalent alternatives that maintain electrical performance and mechanical compatibility within specified operating parameters.

Substiute Parts

1N5643A

Microchip TechnologyIn Stock: 15091N5643A Datasheet

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LCE20A

Littelfuse Inc.In Stock: 1615LCE20A Datasheet

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LCE22A

Littelfuse Inc.In Stock: 1040LCE22A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 1N5643A is determined by electrical and mechanical parameter alignment within the following criteria:

Primary Substitution Parameters:

• Unidirectional Zener TVS diode topology (single channel)
• Reverse standoff voltage range: 20V to 23.1V
• Clamping voltage range: 32.4V to 37.5V
• Peak pulse current capability: minimum 40A
• Peak pulse power rating: 1500W
• Through-hole axial package configuration (DO-13, DO-201, DO-27)
• Operating temperature range: -55°C to 175°C minimum

Identified Substitutes:

The LCE20A (Littelfuse Inc.) and LCE22A (Littelfuse Inc.) meet the electrical performance envelope of the 1N5643A. Both devices operate within the specified voltage and current parameters, maintain equivalent power dissipation ratings, and are available in compatible through-hole axial packages. The LCE series components are active products with current manufacturing status and improved compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

LCE22A Selection: The LCE22A represents the closest electrical equivalent to the 1N5643A, with a reverse standoff voltage of 22V (compared to 23.1V) and clamping voltage of 35.5V (compared to 37.5V). This device maintains the 1500W peak pulse power rating and provides 42A peak pulse current. The LCE22A is an active product with ROHS3 compliance and is available in standard through-hole axial packages (DO-201AA, DO-27). The operating temperature range extends to 175°C, matching the main part specification.

LCE20A Selection: The LCE20A provides an alternative with a lower reverse standoff voltage of 20V and clamping voltage of 32.4V. This device offers enhanced peak pulse current capability at 46A and maintains the 1500W power rating. The LCE20A is suitable for applications where lower voltage thresholds are acceptable and where the increased current margin provides additional design margin. This part is active and ROHS3 compliant.

Compliance Considerations: Both substitute parts achieve ROHS3 compliance, addressing regulatory requirements not met by the discontinued 1N5643A. Both devices maintain the through-hole axial mounting configuration required for direct board-level substitution. Package variants (DO-201AA, DO-27) are mechanically compatible with standard through-hole PCB layouts designed for axial components.

Frequently Asked Questions (FAQ)

Q: Can the LCE22A directly replace the 1N5643A in existing designs?

A: The LCE22A is electrically compatible within the specified operating envelope. The reverse standoff voltage (22V vs. 23.1V) and clamping voltage (35.5V vs. 37.5V) differences are within acceptable tolerance for general-purpose TVS applications. Both devices are unidirectional Zener diodes with identical channel configuration, matching power ratings, and compatible through-hole axial packages. PCB layout modifications are not required.

Q: What is the difference between the LCE20A and LCE22A substitutes?

A: The LCE20A operates at a lower voltage threshold (20V standoff, 32.4V clamp) compared to the LCE22A (22V standoff, 35.5V clamp). The LCE20A provides higher peak pulse current (46A vs. 42A). Selection between these devices depends on the specific voltage protection requirements of the application. The LCE22A provides closer electrical matching to the original 1N5643A specification.

Q: Are there package compatibility concerns with DO-201 versus DO-13?

A: Both DO-201 and DO-13 are through-hole axial packages with compatible lead spacing for standard PCB layouts. The DO-201 package is slightly larger but maintains the same axial lead configuration. No PCB redesign is required for substitution. The LCE series components are available in DO-201AA and DO-27 variants, both suitable for existing through-hole designs.

Q: Does the operating temperature range difference affect substitution?

A: The 1N5643A operates from -65°C to 175°C, while both LCE substitutes operate from -55°C to 175°C. The upper temperature limit is identical. The lower temperature limit difference (-65°C vs. -55°C) is relevant only for applications requiring operation below -55°C. For standard industrial and commercial temperature ranges, this difference does not impact substitution suitability.

Q: What is the significance of ROHS3 compliance on the substitute parts?

A: ROHS3 compliance on the LCE20A and LCE22A indicates conformance to current environmental and material restriction regulations. The original 1N5643A is RoHS non-compliant. Substitution with ROHS3-compliant devices addresses regulatory requirements for new designs and procurement specifications that mandate RoHS compliance.

Q: How do the peak pulse current ratings affect circuit protection?

A: The 1N5643A provides 40A peak pulse current, while the LCE20A provides 46A and the LCE22A provides 42A. Both substitutes meet or exceed the original specification. Higher peak pulse current capability provides additional margin for transient suppression without degrading performance. This represents an improvement over the original design.