SMAJ18C-E3/61 Equivalent & Substitute Parts

Part Overview

The SMAJ18C-E3/61 is a bidirectional transient voltage suppressor (TVS) diode manufactured by Vishay General Semiconductor - Diodes Division. This surface mount component in DO-214AC (SMA) package is designed for general-purpose transient voltage suppression applications. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer Part Number	SMAJ18C-E3/61
Manufacturer	Vishay General Semiconductor - Diodes Division
Category	Transient Voltage Suppressors (TVS)
Package / Case	DO-214AC, SMA
Voltage - Reverse Standoff (Typ)	18V
Voltage - Breakdown (Min)	20V
Voltage - Clamping (Max) @ Ipp	32.2V
Current - Peak Pulse (10/1000µs)	12.4A
Power - Peak Pulse	400W
Operating Temperature	-55°C ~ 150°C (TJ)
Type	Zener
Bidirectional Channels	1
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the SMAJ18C-E3/61 is determined by strict alignment of the following electrical and mechanical parameters:

Critical Matching Parameters:

Reverse Standoff Voltage: 18V (Typ)
Breakdown Voltage (Min): 20V
Package / Case: DO-214AC, SMA
Bidirectional Channels: 1
Mounting Type: Surface Mount
Operating Temperature Range: -55°C minimum to 150°C minimum

Allowable Variation Parameters:

Voltage - Clamping (Max) @ Ipp: 29.2V to 39.3V (within circuit protection requirements)
Current - Peak Pulse (10/1000µs): 12.4A to 102A (higher current capability acceptable)
Power - Peak Pulse: 400W to 600W (higher power rating acceptable)

Substitute parts are grouped into two categories based on clamping voltage performance and current handling capability. Parts with lower clamping voltages (29.2V) provide tighter voltage regulation, while parts with higher clamping voltages (33.2V to 39.3V) offer increased current handling capacity.

Parameter Comparison

Part Number	Manufacturer	Voltage - Reverse Standoff (Typ)	Voltage - Breakdown (Min)	Voltage - Clamping (Max) @ Ipp	Current - Peak Pulse (10/1000µs)	Power - Peak Pulse	Operating Temperature	Package	Product Status
SMAJ18C-E3/61	Vishay General Semiconductor - Diodes Division	18V	20V	32.2V	12.4A	400W	-55°C ~ 150°C	DO-214AC, SMA	Obsolete
SMAJ18CA-E3/61	Vishay General Semiconductor - Diodes Division	18V	20V	29.2V	13.7A	400W	-55°C ~ 150°C	DO-214AC, SMA	Active
SMAJ18C	Taiwan Semiconductor Corporation	18V	20V	32.2V	12.4A	400W	-55°C ~ 150°C	DO-214AC, SMA	Active
ATV04A180JB-HF	Comchip Technology	18V	20V	29.2V	13.7A	400W	-55°C ~ 150°C	DO-214AC, SMA	Active
SM4T21CAY	STMicroelectronics	18V	20V	39.3V	59A (8/20µs)	400W	-55°C ~ 150°C	DO-214AC, SMA	Active
SMA6J18CA-TR	STMicroelectronics	18V	20V	33.2V	102A (8/20µs)	600W	-55°C ~ 175°C	DO-214AC, SMA	Active
SMAJ18CA	MDD	18V	20V	29.2V	13.7A	400W	-50°C ~ 150°C	DO-214AC, SMA	Active
SMAJ18CA-13-F	Diodes Incorporated	18V	20V	29.2V	13.7A	400W	-55°C ~ 150°C	DO-214AC, SMA	Active

Engineering Selection Recommendations

Primary Recommendation: SMAJ18CA-E3/61

This part is the direct Vishay equivalent to the obsolete SMAJ18C-E3/61. It maintains identical reverse standoff voltage (18V), breakdown voltage (20V), and operating temperature range (-55°C ~ 150°C). The clamping voltage is reduced to 29.2V with slightly increased peak pulse current (13.7A vs 12.4A), both acceptable variations for general-purpose transient suppression. Product status is active with full availability. RoHS3 compliance and REACH unaffected status match the original part.

Secondary Recommendation: SMAJ18C (Taiwan Semiconductor Corporation)

This part provides electrical characteristics identical to the original SMAJ18C-E3/61, including 32.2V clamping voltage and 12.4A peak pulse current. It is currently active and available. The part maintains the same package, temperature range, and power rating. This option is suitable when clamping voltage matching is a design requirement.

Alternative for Automotive Applications: ATV04A180JB-HF

This Comchip Technology part is qualified to AEC-Q101 automotive standard and carries active product status. It matches the 18V reverse standoff voltage and 20V breakdown voltage with 29.2V clamping voltage and 13.7A peak pulse current. This option is appropriate for automotive-grade applications requiring formal qualification.

High-Current Alternative: SMA6J18CA-TR

This STMicroelectronics part offers significantly increased current handling (102A at 8/20µs pulse) and power dissipation (600W vs 400W). It maintains the 18V reverse standoff voltage and 20V breakdown voltage with 33.2V clamping voltage. Operating temperature extends to 175°C. This option is suitable for applications requiring enhanced transient suppression capability.

General-Purpose Alternatives: SMAJ18CA (MDD) and SMAJ18CA-13-F (Diodes Incorporated)

Both parts provide 29.2V clamping voltage and 13.7A peak pulse current in active status. The MDD variant operates from -50°C to 150°C, while the Diodes Incorporated part maintains -55°C to 150°C. Both are suitable for general-purpose applications with high inventory availability.

Frequently Asked Questions (FAQ)

Q: Can SMAJ18CA-E3/61 be used as a direct replacement for SMAJ18C-E3/61?

A: Yes. Both parts share identical reverse standoff voltage (18V), breakdown voltage (20V), package (DO-214AC, SMA), and operating temperature range (-55°C ~ 150°C). The clamping voltage difference (29.2V vs 32.2V) and peak pulse current increase (13.7A vs 12.4A) are within acceptable substitution parameters for general-purpose transient suppression.

Q: What is the difference between 10/1000µs and 8/20µs pulse specifications?

A: These represent different test pulse waveforms. The 10/1000µs waveform is a standard transient pulse, while 8/20µs is an alternative pulse shape used in some automotive and industrial standards. Parts specified with 8/20µs pulses (SM4T21CAY, SMA6J18CA-TR) typically handle higher peak currents under this specific waveform condition.

Q: Is the DO-214AC package identical to SMA?

A: Yes. DO-214AC and SMA refer to the same surface mount package. Both designations are used interchangeably in the industry for this component form factor.

Q: Can I use a part with higher clamping voltage than the original?

A: Higher clamping voltages (33.2V to 39.3V) are acceptable substitutes provided the circuit design tolerates the increased voltage transient. Parts with lower clamping voltages (29.2V) provide tighter voltage regulation and are generally preferred when available.

Q: What is the significance of RoHS3 compliance?

A: RoHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead and other hazardous materials. All listed substitute parts maintain RoHS3 compliance, ensuring regulatory alignment with the original part.

Q: Are automotive-qualified parts (AEC-Q101) required for this application?

A: AEC-Q101 qualification is required only for automotive applications. For general-purpose industrial or consumer applications, non-automotive qualified parts are acceptable. ATV04A180JB-HF and SM4T21CAY carry automotive qualification if needed.

Q: What inventory considerations should I evaluate?

A: Inventory availability varies significantly among substitutes. SMAJ18CA (MDD) offers the highest inventory (72,210 pcs), while SMAJ18CA-13-F (Diodes Incorporated) provides 26,075 pcs. Vishay SMAJ18CA-E3/61 maintains 5,894 pcs. Evaluate lead times and supply chain stability based on your procurement timeline.

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