SA18CA Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The SA18CA is a Transient Voltage Suppressor (TVS) diode in DO-15 (DO-204AC) axial package designed for general-purpose overvoltage protection applications. Manufactured by onsemi, this bidirectional zener TVS diode provides transient suppression with an 18V reverse standoff voltage and 29.2V maximum clamping voltage at peak pulse current. The original onsemi SA18CA is classified as obsolete, necessitating identification of active equivalent and substitute parts from alternative manufacturers to maintain design continuity and ensure component availability for new production and field replacements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	18	V
Voltage - Breakdown (Min)	20	V
Voltage - Clamping (Max) @ Ipp	29.2	V
Current - Peak Pulse (10/1000µs)	17.2	A
Power - Peak Pulse	500	W
Type	Zener	-
Bidirectional Channels	1	-
Mounting Type	Through Hole	-
Package / Case	DO-204AC, DO-15, Axial	-
Applications	General Purpose	-

Substitute Part Grouping Explanation

Substitution of the obsolete onsemi SA18CA is determined by strict electrical and mechanical parameter matching within the TVS diode category. The following criteria establish valid substitution relationships:

Primary Substitution Criteria:

Reverse standoff voltage: 18V (±tolerance)
Breakdown voltage minimum: 20V
Clamping voltage maximum @ Ipp: 29.2V to 30.6V range
Peak pulse current: 17.2A to 20A range
Power dissipation: 500W to 600W
Package type: DO-15 (DO-204AC) axial through-hole
Bidirectional zener configuration

Substitute Categories:

Direct Equivalents maintain identical electrical specifications and packaging, enabling pin-for-pin replacement without circuit modification.

Compatible Substitutes operate within the allowed parameter ranges for the application, with minor variations in clamping voltage or peak pulse current that remain within acceptable design margins for general-purpose transient suppression.

Parameter Comparison

Part Number	Manufacturer	Product Status	Vwm (Typ) V	Vbr (Min) V	Vc (Max) @ Ipp V	Ipp (10/1000µs) A	Ppk W	Package	Inventory Pcs
SA18CA	onsemi	Obsolete	18	20	29.2	17.2	500	DO-15	2145
SA18CA	Taiwan Semiconductor Corporation	Active	18	20	39.4	17.9	500	DO-204AC	2145
P6KE22CA	Diotec Semiconductor	Active	18.8	20.9	30.6	20	600	DO-15	88623
P5KE18CA-TP	Micro Commercial Co	Active	18	20	29.2	17.2	500	DO-15	1173
P5KE18CA-BP	Micro Commercial Co	Active	18	20	29.2	17.2	500	DO-15	1063
P5KE18CA-AP	Micro Commercial Co	Active	18	20	29.2	17.2	500	DO-15	649
SA18CA-TP	Micro Commercial Co	Active	18	20	29.2	17.5	500	DO-15	1139

Engineering Selection Recommendations

Direct Replacement Priority:

The P5KE18CA series (P5KE18CA-TP, P5KE18CA-BP, P5KE18CA-AP) from Micro Commercial Co provides direct electrical equivalence to the obsolete onsemi SA18CA, with identical reverse standoff voltage (18V), breakdown voltage (20V minimum), clamping voltage (29.2V), and peak pulse current (17.2A). All variants are active products with REACH compliance and EAR99 classification. Selection among P5KE18CA variants depends on packaging requirements (Tape & Reel, Bulk) and inventory availability.

Alternative Equivalent:

The SA18CA from Taiwan Semiconductor Corporation maintains identical voltage specifications (18V standoff, 20V breakdown) and is actively manufactured. This part operates within the same electrical class despite higher clamping voltage (39.4V) and marginally increased peak pulse current (17.9A), both within acceptable design tolerances for general-purpose applications.

Compatible Substitute:

The P6KE22CA from Diotec Semiconductor operates within the allowed parameter range with slightly elevated reverse standoff voltage (18.8V) and clamping voltage (30.6V), with increased peak pulse current capability (20A) and power dissipation (600W). This part is suitable for applications where slightly higher transient suppression margins are acceptable. Diotec P6KE22CA is RoHS3 compliant and actively produced with high inventory availability (88,623 units).

Product Status Consideration:

All recommended substitutes are active products with current manufacturing status, ensuring long-term availability and supply chain continuity. The obsolete onsemi SA18CA should be phased out in favor of active alternatives.

Frequently Asked Questions (FAQ)

Q: Can the P5KE18CA series directly replace the obsolete onsemi SA18CA without circuit modification?

A: Yes. The P5KE18CA-TP, P5KE18CA-BP, and P5KE18CA-AP variants from Micro Commercial Co are direct electrical and mechanical equivalents with identical reverse standoff voltage (18V), breakdown voltage (20V), clamping voltage (29.2V), peak pulse current (17.2A), and DO-15 package configuration. No circuit changes are required.

Q: What is the difference between P5KE18CA-TP, P5KE18CA-BP, and P5KE18CA-AP?

A: These part numbers represent the same electrical device with different packaging configurations. The suffix indicates packaging type: -TP (Tape & Reel), -BP (Bulk), and -AP (Bulk alternative). Electrical performance is identical; selection depends on procurement and assembly requirements.

Q: Is the Taiwan Semiconductor Corporation SA18CA a suitable replacement?

A: Yes. The TSC SA18CA maintains identical voltage specifications (18V standoff, 20V breakdown) and is an active product. The higher clamping voltage (39.4V) and marginally increased peak pulse current (17.9A) remain within acceptable design margins for general-purpose transient suppression applications.

Q: Can the P6KE22CA from Diotec be used as a substitute?

A: Yes, with design consideration. The P6KE22CA operates within the allowed parameter range with slightly elevated standoff voltage (18.8V) and clamping voltage (30.6V), providing enhanced transient suppression capability. This part is suitable for applications where additional protection margin is beneficial. Verify that the higher clamping voltage does not exceed downstream component voltage ratings.

Q: Are all substitute parts RoHS and REACH compliant?

A: All recommended substitutes carry REACH compliance and EAR99 classification. The P6KE22CA from Diotec is explicitly RoHS3 compliant. Verify specific compliance documentation with your supplier for the selected part variant.

Q: What inventory levels are available for each substitute?

A: Inventory availability varies: P6KE22CA (88,623 units), P5KE18CA-TP (1,173 units), SA18CA-TP (1,139 units), P5KE18CA-BP (1,063 units), P5KE18CA-AP (649 units). High availability of the P6KE22CA supports rapid procurement for production requirements.

Q: Does package type affect substitution compatibility?

A: No. All substitute parts use the DO-15 (DO-204AC) axial through-hole package, which is mechanically and electrically compatible with the original onsemi SA18CA. Board layout and assembly processes require no modification.

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