SMAJ18CA-13 Equivalent & Substitute Parts

Part Overview

The SMAJ18CA-13 is a transient voltage suppressor (TVS) diode manufactured by Diodes Incorporated in the DO-214AC (SMA) surface mount package. This component provides bidirectional transient voltage protection with an 18V reverse standoff voltage and 29.2V maximum clamping voltage at peak pulse current. The part is currently listed as obsolete, necessitating identification of active equivalent and substitute components that maintain electrical and mechanical compatibility for new designs and production continuity.

Key Parameters

Parameter	Value
Voltage - Reverse Standoff (Typ)	18V
Voltage - Breakdown (Min)	20V
Voltage - Clamping (Max) @ Ipp	29.2V
Current - Peak Pulse (10/1000µs)	13.7A
Power - Peak Pulse	400W
Package / Case	DO-214AC, SMA
Mounting Type	Surface Mount
Operating Temperature	-55°C ~ 150°C (TJ)
Type	Zener
Bidirectional Channels	1

Substitute Part Grouping Explanation

Substitution of the SMAJ18CA-13 is determined by strict equivalence across the following electrical and mechanical parameters:

Voltage - Reverse Standoff: 18V (nominal)
Voltage - Breakdown: 20V (minimum)
Voltage - Clamping: 29.2V (maximum at Ipp)
Current - Peak Pulse: 13.7A (10/1000µs)
Power - Peak Pulse: 400W
Package: DO-214AC (SMA)
Mounting: Surface Mount
Bidirectional operation with single channel

Parts meeting all these criteria are classified as direct electrical equivalents. Parts with identical electrical specifications but different packaging or product status are classified as functional equivalents. Parts with variations in clamping voltage or peak pulse current are classified as alternative suppressors within the same voltage class and are suitable only where the specific electrical variation is acceptable for the application.

Parameter Comparison

Manufacturer	Part Number	Vwm (Typ)	Vbr (Min)	Vc (Max)	Ipp (10/1000µs)	Ppk	Package	Status	RoHS
Diodes Incorporated	SMAJ18CA-13	18V	20V	29.2V	13.7A	400W	DO-214AC (SMA)	Obsolete	Non-compliant
Diodes Incorporated	SMAJ18CA-13-F	18V	20V	29.2V	13.7A	400W	DO-214AC (SMA)	Active	ROHS3 Compliant
Comchip Technology	ATV04A180JB-HF	18V	20V	29.2V	13.7A	400W	DO-214AC (SMA)	Active	ROHS3 Compliant
Panjit International Inc.	P4SMAJ18CA_R1_00001	18V	20V	29.2V	13.7A	400W	DO-214AC (SMA)	Active	ROHS3 Compliant
Panjit International Inc.	P4SMAJ18CAS_R1_00001	18V	20V	29.2V	13.7A	400W	DO-214AC (SMA)	Active	ROHS3 Compliant
STMicroelectronics	SM4T21CAY	18V	20V	39.3V	59A (8/20µs)	400W	DO-214AC (SMA)	Active	ROHS3 Compliant
Taiwan Semiconductor Corporation	SMAJ18C	18V	20V	32.2V	12.4A	400W	DO-214AC (SMA)	Active	ROHS3 Compliant
MDD	SMAJ18CA	18V	20V	29.2V	13.7A	400W	DO-214AC (SMA)	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Electrical Equivalents (Identical Specifications):

SMAJ18CA-13-F (Diodes Incorporated), P4SMAJ18CA_R1_00001 (Panjit International Inc.), P4SMAJ18CAS_R1_00001 (Panjit International Inc.), and SMAJ18CA (MDD) are direct electrical equivalents with identical voltage and current ratings. All are active products with ROHS3 compliance. SMAJ18CA-13-F is the recommended primary substitute as it is manufactured by the original supplier and maintains full specification alignment. Panjit and MDD alternatives provide equivalent electrical performance with active product status and regulatory compliance.

Automotive-Qualified Alternative:

ATV04A180JB-HF (Comchip Technology) provides identical electrical specifications with AEC-Q101 automotive qualification. This part is suitable for applications requiring automotive-grade components and maintains full electrical compatibility.

Alternative Suppressors (Specification Variations):

SM4T21CAY (STMicroelectronics) and SMAJ18C (Taiwan Semiconductor Corporation) operate within the same 18V voltage class but exhibit different clamping voltages and peak pulse currents. SM4T21CAY features higher clamping voltage (39.3V) and peak pulse current (59A at 8/20µs), while SMAJ18C exhibits slightly higher clamping voltage (32.2V) with marginally lower peak pulse current (12.4A). These parts are suitable only where the electrical variation is acceptable for the specific application circuit.

Frequently Asked Questions (FAQ)

Q: Can SMAJ18CA-13-F be used as a direct replacement for SMAJ18CA-13?

A: Yes. SMAJ18CA-13-F is manufactured by Diodes Incorporated and maintains identical electrical specifications: 18V reverse standoff, 20V breakdown minimum, 29.2V clamping maximum, and 13.7A peak pulse current. The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 compliant). Packaging and mounting type are identical.

Q: What is the difference between SMAJ18CA-13-F and P4SMAJ18CA_R1_00001?

A: Both parts are direct electrical equivalents with identical voltage and current ratings. The differences are manufacturer (Diodes Incorporated versus Panjit International Inc.) and packaging designation (Tape & Reel for both). Selection between these parts depends on supplier availability, lead time, and cost considerations. Electrical performance is equivalent.

Q: Is SM4T21CAY a suitable substitute?

A: SM4T21CAY operates within the same 18V voltage class but exhibits different electrical characteristics: 39.3V clamping voltage (versus 29.2V) and 59A peak pulse current at 8/20µs (versus 13.7A at 10/1000µs). This part is suitable only if the application circuit can accommodate higher clamping voltage and the different pulse waveform specification. Direct substitution without circuit analysis is not recommended.

Q: Why is SMAJ18C not recommended as a primary substitute?

A: SMAJ18C exhibits a higher clamping voltage (32.2V versus 29.2V) and lower peak pulse current (12.4A versus 13.7A). While it operates in the same voltage class, these electrical variations may affect circuit performance. Use only if application requirements accommodate the specification differences.

Q: Are all substitute parts available in the same DO-214AC (SMA) package?

A: Yes. All listed substitute parts use the DO-214AC (SMA) surface mount package, ensuring mechanical and footprint compatibility. Mounting type is surface mount for all alternatives.

Q: What is the operating temperature range for substitute parts?

A: All substitute parts operate across -55°C to 150°C junction temperature, matching the original SMAJ18CA-13 specification. MDD SMAJ18CA variant operates -50°C to 150°C, which is a narrower range suitable for applications not requiring the full -55°C lower limit.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts listed are ROHS3 compliant. The original SMAJ18CA-13 is RoHS non-compliant. For applications requiring RoHS compliance, any of the active substitute parts are suitable.

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