SMTY18AM Equivalent & Substitute Parts

Part Overview

The SMTY18AM is a transient voltage suppressor (TVS) diode manufactured by STMicroelectronics, classified as a unidirectional zener-type device in the DO-216AA surface mount package. This component is designed for general-purpose transient voltage suppression applications with a 16V reverse standoff voltage and 20V maximum clamping voltage. The SMTY18AM is currently listed as obsolete, necessitating identification of active equivalent and substitute components to maintain design continuity and ensure ongoing component availability for production and repair applications.

Key Parameters

Parameter	SMTY18AM
Manufacturer	STMicroelectronics
Category	Transient Voltage Suppressors (TVS)
Type	Zener
Unidirectional Channels	1
Voltage - Reverse Standoff (Typ)	16V
Voltage - Clamping (Max) @ Ipp	20V
Power - Peak Pulse	400W
Mounting Type	Surface Mount
Package / Case	DO-216AA
Product Status	Obsolete
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the SMTY18AM is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

Unidirectional zener-type TVS diode configuration
Reverse standoff voltage within acceptable operating range
Clamping voltage compatible with circuit protection requirements
Peak pulse power rating sufficient for transient suppression
Surface mount package type (DO-216AA)

Mechanical Compatibility Criteria:

DO-216AA package footprint and pinout
Surface mount assembly compatibility
Moisture sensitivity level MSL 1 (unlimited shelf life)

The substitute parts listed are Microchip Technology UPT series devices, all housed in the DO-216AA package with identical mounting characteristics. These devices operate across the voltage ranges specified for the SMTY18AM application space, with clamping voltages ranging from 18V to 29.2V and peak pulse power ratings of 1000W, providing enhanced performance margins compared to the original 400W specification.

Parameter Comparison

Parameter	SMTY18AM	UPT10/TR13	UPT10/TR7	UPT10E3/TR13	UPT15/TR13	UPT15/TR7	UPT15E3/TR13	UPT15RE3/TR7	UPT17/TR13	UPT17/TR7	UPT17E3/TR13
Manufacturer	STMicroelectronics	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology	Microchip Technology
Type	Zener	Zener	Zener	Zener	Zener	Zener	Zener	Zener	Zener	Zener	Zener
Unidirectional Channels	1	1	1	1	1	1	1	1	1	1	1
Voltage - Reverse Standoff (Typ)	16V	10V	10V	10V	15V	15V	15V	15V	17V	17V	17V
Voltage - Clamping (Max) @ Ipp	20V	18V	18V	18V	26V	26V	26V	26V	29.2V	29.2V	29.2V
Current - Peak Pulse (10/1000µs)	—	8.33A	8.33A	8.33A	5.77A	5.77A	5.77A	5.77A	5.14A	5.14A	5.14A
Power - Peak Pulse	400W	1000W	1000W	1000W	1000W	1000W	1000W	1000W	1000W	1000W	1000W
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA	DO-216AA
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	RoHS non-compliant	RoHS non-compliant	ROHS3 Compliant	RoHS non-compliant	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant	RoHS non-compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitutes (ROHS3 Compliant):

For applications requiring ROHS3 compliance matching the original SMTY18AM specification, the following Microchip Technology devices are recommended:

UPT10E3/TR13: 10V standoff, 18V clamping voltage. Suitable for lower voltage protection circuits. ROHS3 compliant.
UPT15E3/TR13: 15V standoff, 26V clamping voltage. Closest electrical performance to SMTY18AM. ROHS3 compliant.
UPT15RE3/TR7: 15V standoff, 26V clamping voltage. Identical electrical specifications to UPT15E3/TR13 with alternative tape reel configuration. ROHS3 compliant.
UPT17E3/TR13: 17V standoff, 29.2V clamping voltage. Higher voltage protection capability. ROHS3 compliant.

Secondary Substitutes (RoHS Non-Compliant):

For applications where RoHS compliance is not required, the following Microchip Technology devices provide active product status and enhanced power dissipation:

UPT10/TR13 and UPT10/TR7: 10V standoff, 18V clamping voltage.
UPT15/TR13 and UPT15/TR7: 15V standoff, 26V clamping voltage.
UPT17/TR13 and UPT17/TR7: 17V standoff, 29.2V clamping voltage.

Selection Criteria:

All substitute devices share identical DO-216AA package geometry and surface mount assembly compatibility with the SMTY18AM. The UPT series devices provide 2.5× higher peak pulse power rating (1000W versus 400W), offering enhanced transient suppression capability. Selection between UPT10, UPT15, and UPT17 variants depends on the specific reverse standoff voltage requirement of the protected circuit. Tape reel configuration (TR13 or TR7) represents packaging format variation without electrical performance impact.

Frequently Asked Questions (FAQ)

Q: Can UPT10E3/TR13 replace SMTY18AM in all applications?

A: UPT10E3/TR13 operates at a lower reverse standoff voltage (10V versus 16V) and lower clamping voltage (18V versus 20V). Substitution is valid only for circuits designed to operate at or below 10V standoff voltage. For circuits requiring 16V standoff protection, UPT15E3/TR13 or UPT17E3/TR13 are appropriate selections.

Q: What is the difference between UPT15E3/TR13 and UPT15RE3/TR7?

A: Both devices have identical electrical specifications: 15V reverse standoff voltage and 26V clamping voltage. The difference is packaging format. TR13 and TR7 designations indicate different tape reel configurations used during manufacturing and distribution. Both are ROHS3 compliant and suitable for SMTY18AM replacement.

Q: Why do some substitute parts show RoHS non-compliant status?

A: UPT10/TR13, UPT10/TR7, UPT15/TR13, UPT15/TR7, UPT17/TR13, and UPT17/TR7 are RoHS non-compliant variants of the same electrical specifications as their E3 counterparts. These devices are suitable for applications where RoHS3 compliance is not a requirement. For new designs or applications requiring regulatory compliance, ROHS3-compliant variants (E3 suffix) are recommended.

Q: Are all substitute parts in the same DO-216AA package?

A: Yes. All listed substitute parts use the DO-216AA surface mount package, providing identical footprint and assembly compatibility with the SMTY18AM. No PCB layout modifications are required for substitution.

Q: What is the significance of the higher 1000W power rating in UPT series devices?

A: The UPT series devices are rated for 1000W peak pulse power compared to the SMTY18AM's 400W rating. This represents enhanced transient suppression capability and improved thermal performance during high-energy transient events. The higher power rating does not affect compatibility; it provides additional design margin for transient protection.

Q: Can I use UPT17E3/TR13 as a universal replacement for SMTY18AM?

A: UPT17E3/TR13 has a higher reverse standoff voltage (17V versus 16V) and higher clamping voltage (29.2V versus 20V). This device provides protection at higher voltage levels. Substitution is valid for circuits where the higher voltage thresholds are acceptable. For circuits requiring exact voltage matching to the original 16V/20V specification, UPT15E3/TR13 is the more appropriate selection.

Q: What inventory levels are available for substitute parts?

A: Current inventory levels are: UPT10/TR13 (774 pcs), UPT10/TR7 (707 pcs), UPT10E3/TR13 (729 pcs), UPT15/TR13 (1146 pcs), UPT15/TR7 (779 pcs), UPT15E3/TR13 (711 pcs), UPT15RE3/TR7 (1111 pcs), UPT17/TR13 (1035 pcs), UPT17/TR7 (847 pcs), and UPT17E3/TR13 (661 pcs). All substitute parts are listed as active products with new original stock availability.

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