SA18C-B Equivalent & Substitute Parts

Part Overview

The SA18C-B is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for telecom applications. This bidirectional Zener diode operates with an 18V reverse standoff voltage and provides 500W peak pulse power protection in a through-hole DO-204AC (DO-15) package. The SA18C-B is classified as obsolete, making identification of equivalent substitute parts necessary for ongoing system maintenance and new design implementations where this component is specified.

Substiute Parts

SA18C-B

Littelfuse Inc.In Stock: 911SA18C-B Datasheet

Current PartRFQ

SA18CA

Taiwan Semiconductor CorporationIn Stock: 2251SA18CA Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SA18C-B is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Voltage - Reverse Standoff (Typ): 18V
• Voltage - Breakdown (Min): 20V
• Bidirectional Channels: 1
• Type: Zener
• Power - Peak Pulse: 500W

Mechanical Compatibility Criteria:

• Mounting Type: Through Hole
• Package / Case: DO-204AC (DO-15)

Functional Compatibility Criteria:

• Current - Peak Pulse (10/1000µs): 17.5A (minimum threshold)

The SA18CA qualifies as a direct substitute based on matching all critical electrical parameters (18V standoff, 20V minimum breakdown, 1 bidirectional channel, Zener type, 500W peak pulse power) and mechanical parameters (through-hole mounting, DO-204AC package). The SA18CA demonstrates improved current handling (17.9A vs. 17.5A) and maintains functional equivalence within the specified parameter envelope.

Parameter Comparison

Engineering Selection Recommendations

The SA18CA is an active-status substitute for the obsolete SA18C-B. Both components share identical reverse standoff voltage (18V), breakdown voltage (20V minimum), bidirectional channel configuration (1), Zener type classification, and peak pulse power rating (500W). Both are housed in the DO-204AC (DO-15) through-hole package and maintain unlimited moisture sensitivity levels.

The SA18CA demonstrates superior compliance status with ROHS3 certification compared to the SA18C-B's RoHS Compliant designation. The SA18CA also carries REACH Unaffected status, providing additional regulatory clarity for international applications.

The SA18CA exhibits a higher clamping voltage (39.4V vs. 29.2V) and marginally improved peak pulse current (17.9A vs. 17.5A). The SA18CA operates across a narrower temperature range (-55°C to 175°C vs. -65°C to 175°C), which remains suitable for standard industrial and telecom applications.

Selection of the SA18CA is appropriate for applications where the SA18C-B is specified, provided the higher clamping voltage and narrower low-temperature operating range are compatible with system requirements.

Frequently Asked Questions (FAQ)

Q: Can the SA18CA directly replace the SA18C-B in existing designs?

A: The SA18CA is electrically and mechanically compatible with the SA18C-B. Both components share the same 18V reverse standoff voltage, 20V minimum breakdown voltage, 1 bidirectional channel, Zener type, 500W peak pulse power, and DO-204AC through-hole package. Verification of the SA18CA's higher clamping voltage (39.4V vs. 29.2V) and narrower operating temperature range (-55°C to 175°C vs. -65°C to 175°C) against system specifications is required before implementation.

Q: What are the key differences between SA18C-B and SA18CA?

A: The primary differences are product status (SA18C-B is obsolete; SA18CA is active), clamping voltage (29.2V vs. 39.4V), peak pulse current (17.5A vs. 17.9A), operating temperature range (-65°C to 175°C vs. -55°C to 175°C), and regulatory compliance (RoHS Compliant vs. ROHS3 Compliant with REACH Unaffected status).

Q: Are the packages identical between SA18C-B and SA18CA?

A: Yes. Both components use the DO-204AC (DO-15) axial through-hole package. The SA18CA is supplied in Tape & Reel (TR) packaging format, while the SA18C-B packaging format is not specified in available data. Both are suitable for through-hole PCB assembly.

Q: Does the SA18CA meet current RoHS requirements?

A: Yes. The SA18CA carries ROHS3 Compliant certification and REACH Unaffected status, meeting current regulatory requirements for electronic components in most jurisdictions.

Q: What is the impact of the SA18CA's higher clamping voltage on circuit protection?

A: The SA18CA's clamping voltage of 39.4V is higher than the SA18C-B's 29.2V. This parameter defines the maximum voltage across the diode during transient suppression. Circuit designs must verify that the higher clamping voltage remains within acceptable limits for protected components and system specifications.

Q: Is the SA18CA suitable for telecom applications like the SA18C-B?

A: The SA18CA is classified for general-purpose applications rather than telecom-specific use. However, the electrical and mechanical parameters remain compatible with telecom transient suppression requirements. Application suitability must be confirmed against specific system specifications and performance criteria.