1SMB170AT3 Transient Voltage Suppressor Diode – Equivalent & Substitute Parts

Part Overview

The 1SMB170AT3 is a unidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection in surface-mount applications. This component features a 170V reverse standoff voltage, 275V maximum clamping voltage, and 2.2A peak pulse current capability in a DO-214AA (SMB) package. The part is currently obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity.

Key Parameters

Parameter	Value	Unit
Voltage – Reverse Standoff (Typ)	170	V
Voltage – Breakdown (Min)	189	V
Voltage – Clamping (Max) @ Ipp	275	V
Current – Peak Pulse (10/1000µs)	2.2	A
Power – Peak Pulse	600	W
Type	Zener	–
Unidirectional Channels	1	–
Package / Case	DO-214AA, SMB	–
Operating Temperature	-65 to 150	°C (TJ)
Mounting Type	Surface Mount	–

Substitute Part Grouping Explanation

Substitution eligibility for the 1SMB170AT3 is determined by the following critical parameters:

Primary Matching Criteria:

Voltage – Reverse Standoff: 170V (±tolerance)
Voltage – Clamping (Max) @ Ipp: 275V (±tolerance)
Current – Peak Pulse (10/1000µs): 2.2A (±tolerance)
Package / Case: DO-214AA or SMB equivalent
Type: Zener diode, unidirectional configuration
Mounting Type: Surface Mount

Secondary Compatibility Factors:

Operating Temperature Range: Must encompass or exceed -65°C to 150°C
Power – Peak Pulse: 600W minimum
RoHS and REACH compliance status (for regulatory alignment)

Substitute parts are classified into two categories:

Direct Equivalents: Parts matching all primary criteria with identical electrical performance specifications.

Similar Alternatives: Parts with the same voltage and current ratings but differing in secondary parameters such as temperature range, RoHS compliance, or bidirectional channel configuration. These require design review to confirm compatibility with application constraints.

Parameter Comparison

Part Number	Manufacturer	VWM (V)	Clamp (V)	Ipp (A)	Channels	Temp Range (°C)	Package	Status	RoHS
1SMB170AT3	onsemi	170	275	2.2	Unidirectional	-65 to 150	DO-214AA, SMB	Obsolete	Non-compliant
SMBJ170A	Fairchild Semiconductor	170	275	2.2	Unidirectional	-55 to 150	DO-214AA, SMB	Active	Not specified
SMBJ170A-13	Diodes Incorporated	170	275	2.2	Unidirectional	-55 to 150	DO-214AA, SMB	Discontinued	Non-compliant
SMBJ170A-13-F	Diodes Incorporated	170	275	2.2	Unidirectional	-55 to 150	DO-214AA, SMB	Active	ROHS3 Compliant
SMBJ170A-TR	STMicroelectronics	170	275	2.2	Unidirectional	-55 to 150	DO-214AA, SMB	Active	ROHS3 Compliant
SMBJ170AE3/TR13	Microchip Technology	170	275	2.2	Unidirectional	-65 to 150	DO-214AA, SMB	Active	ROHS3 Compliant
SMBJ170CA-TR	STMicroelectronics	170	275	2.2	Bidirectional	-55 to 150	DO-214AA, SMB	Active	ROHS3 Compliant
SMBJ170E3/TR13	Microchip Technology	170	304	2.0	Unidirectional	-65 to 150	DO-214AA, SMB	Active	ROHS3 Compliant
SMBJ160CA-TP	Micro Commercial Co	160	259	2.3	Bidirectional	-55 to 175	DO-214AA, SMB	Active	ROHS3 Compliant

Engineering Selection Recommendations

Preferred Direct Equivalents:

SMBJ170A-13-F (Diodes Incorporated) and SMBJ170A-TR (STMicroelectronics) are the primary recommended substitutes. Both maintain identical electrical specifications (170V standoff, 275V clamp, 2.2A peak pulse) and unidirectional channel configuration. Both are active products with ROHS3 compliance, ensuring long-term availability and regulatory alignment for new designs.

SMBJ170AE3/TR13 (Microchip Technology) is an additional equivalent option with identical electrical performance and the extended temperature range (-65°C to 150°C) matching the original 1SMB170AT3 specification. This part is ROHS3 compliant and actively produced.

Conditional Alternatives:

SMBJ170CA-TR (STMicroelectronics) provides identical voltage and current ratings but features bidirectional channel configuration. This part is suitable only if the application circuit can accommodate bidirectional transient suppression. It is ROHS3 compliant and actively produced.

SMBJ170E3/TR13 (Microchip Technology) exhibits a higher clamping voltage (304V vs. 275V) and slightly reduced peak pulse current (2.0A vs. 2.2A). Selection requires confirmation that the application tolerates the elevated clamping voltage and reduced current capacity.

SMBJ160CA-TP (Micro Commercial Co) operates at 160V standoff with 259V clamping voltage, representing a lower voltage rating. This part is suitable only for applications where reduced voltage protection is acceptable.

Obsolete or Discontinued Parts:

SMBJ170A-13 (Diodes Incorporated) is discontinued at DiGi Electronics and should not be selected for new designs requiring long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can SMBJ170A-TR directly replace 1SMB170AT3 in existing designs?

A: Yes. SMBJ170A-TR matches all critical electrical parameters: 170V reverse standoff, 275V clamping voltage, 2.2A peak pulse current, and unidirectional configuration. The package is identical (DO-214AA/SMB). The only difference is the operating temperature range (-55°C to 150°C vs. -65°C to 150°C), which is acceptable for most applications operating above -55°C.

Q: What is the difference between unidirectional and bidirectional TVS diodes?

A: Unidirectional TVS diodes (like 1SMB170AT3 and SMBJ170A) suppress transients in one direction only, suitable for protecting against overvoltage on a single polarity line. Bidirectional TVS diodes (like SMBJ170CA-TR) suppress transients in both directions, used for AC signal lines or bidirectional data lines. Selection depends on circuit topology.

Q: Is SMBJ170AE3/TR13 compatible with designs requiring the full -65°C to 150°C temperature range?

A: Yes. SMBJ170AE3/TR13 maintains the extended temperature range (-65°C to 150°C) of the original 1SMB170AT3, making it suitable for applications with extreme low-temperature requirements.

Q: Why does SMBJ170E3/TR13 have a higher clamping voltage (304V)?

A: SMBJ170E3/TR13 is a variant within the SMBJ170 series with different internal design parameters. The 304V clamping voltage is a specified characteristic of this part. Use only if the application circuit can tolerate this elevated clamping level without component damage.

Q: Are all recommended substitutes RoHS compliant?

A: SMBJ170A-13-F, SMBJ170A-TR, SMBJ170AE3/TR13, SMBJ170CA-TR, SMBJ170E3/TR13, and SMBJ160CA-TP are all ROHS3 compliant. The original 1SMB170AT3 is RoHS non-compliant. For new designs subject to RoHS regulations, select from the compliant alternatives.

Q: What packaging options are available for these substitutes?

A: All listed substitutes use the DO-214AA (SMB) surface-mount package, maintaining mechanical and thermal compatibility with the original 1SMB170AT3. Packaging variants (Tape & Reel, Cut Tape, Digi-Reel) affect supply format but not component functionality or footprint.

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