SA170-B Equivalent & Substitute Parts

Part Overview

The SA170-B is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for transient overvoltage protection in telecom applications. This component features a 170V reverse standoff voltage with a 275V maximum clamping voltage and 1.9A peak pulse current capability in a through-hole DO-204AC (DO-15) axial package.

The SA170-B is classified as obsolete. Locating equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or repair requirements for systems utilizing this component.

Substiute Parts

SA170-B

Littelfuse Inc.In Stock: 1203SA170-B Datasheet

Current PartRFQ

SA170A

Taiwan Semiconductor CorporationIn Stock: 1033SA170A Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SA170-B with alternative TVS diodes is determined by strict equivalence across the following critical electrical and mechanical parameters:

Voltage Parameters: The reverse standoff voltage (170V typical), minimum breakdown voltage (189V), and maximum clamping voltage (275V) must remain identical to ensure proper transient suppression without affecting normal circuit operation.

Current Rating: Peak pulse current capability must be sufficient to handle the transient energy without component degradation.

Package Compatibility: The substitute must utilize the same DO-204AC (DO-15) through-hole axial package to ensure mechanical and electrical compatibility with existing printed circuit board layouts.

Temperature Range: Operating temperature specifications must encompass or exceed the original component's range to maintain performance across all environmental conditions.

Device Type: The substitute must be a unidirectional Zener-type TVS diode with a single channel configuration.

The SA170A meets these substitution criteria through identical voltage specifications, compatible package format, and equivalent functional performance within the TVS diode category.

Parameter Comparison

Engineering Selection Recommendations

SA170A as Primary Substitute:

The SA170A from Taiwan Semiconductor Corporation is the direct equivalent substitute for the obsolete SA170-B. Both components share identical voltage specifications (170V standoff, 189V breakdown, 275V clamping) and are housed in the same DO-204AC through-hole axial package, ensuring direct mechanical and electrical compatibility.

The SA170A carries an Active product status, providing assured long-term availability compared to the obsolete SA170-B. Both components maintain RoHS compliance (SA170-B: RoHS Compliant; SA170A: ROHS3 Compliant), supporting environmental and regulatory requirements.

Temperature Consideration:

The SA170A operates across -55°C to 175°C, compared to the SA170-B range of -65°C to 175°C. The SA170A's minimum operating temperature is 10°C higher. Applications requiring operation below -55°C require evaluation against specific system thermal requirements.

Current Rating Difference:

The SA170A specifies 100mA peak pulse current versus the SA170-B's 1.9A rating. This difference reflects different transient energy handling capabilities. Applications with peak pulse currents exceeding 100mA require confirmation that the SA170A's current rating is adequate for the intended circuit protection function.

Compliance and Availability:

The SA170A's Active status and ROHS3 compliance designation provide superior supply chain continuity and regulatory alignment for new designs and ongoing production support.

Frequently Asked Questions (FAQ)

Q: Can the SA170A directly replace the SA170-B in existing circuit designs?

A: The SA170A provides direct mechanical and electrical substitution for voltage specifications and package format. However, the reduced peak pulse current rating (100mA versus 1.9A) requires confirmation that transient energy levels in the application do not exceed the SA170A's capability. The operating temperature minimum of -55°C (versus -65°C) must be evaluated against system environmental specifications.

Q: What are the critical parameters that determine TVS diode substitution?

A: Substitution is determined by: (1) identical reverse standoff voltage, (2) identical breakdown voltage minimum, (3) identical clamping voltage maximum, (4) compatible or superior peak pulse current rating, (5) identical package and mounting type, and (6) operating temperature range that encompasses or exceeds the original specification.

Q: Are both components RoHS compliant?

A: Yes. The SA170-B is RoHS Compliant, and the SA170A is ROHS3 Compliant. Both meet environmental and regulatory requirements for restricted substance use.

Q: What is the difference in peak pulse current between these components?

A: The SA170-B is rated for 1.9A peak pulse current, while the SA170A is rated for 100mA. This represents a significant difference in transient energy handling capacity. Applications must confirm that peak pulse currents remain within the SA170A's 100mA specification.

Q: Does the SA170A's higher minimum operating temperature affect compatibility?

A: The SA170A operates from -55°C minimum, compared to the SA170-B's -65°C minimum. Applications requiring operation below -55°C must evaluate whether the SA170A's temperature range is acceptable for the intended environment.

Q: Are both components available in the same package format?

A: Yes. Both the SA170-B and SA170A utilize the DO-204AC (DO-15) through-hole axial package, ensuring identical mechanical compatibility with existing printed circuit board layouts and assembly processes.

Q: What is the product status difference between these components?

A: The SA170-B is classified as Obsolete, indicating discontinued manufacturing and limited availability. The SA170A is classified as Active, indicating current production and assured long-term supply availability.