SMAJ8.5 Equivalent & Substitute Parts

Part Overview

The SMAJ8.5 is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features an 8.5V reverse standoff voltage with a 15.12V maximum clamping voltage and 27.8A peak pulse current capability in a surface-mount DO-214AC (SMA) package. The main part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for ongoing production and field replacement requirements.

Key Parameters

Parameter	Value	Unit
Reverse Standoff Voltage (Typ)	8.5	V
Breakdown Voltage (Min)	8.93	V
Clamping Voltage (Max) @ Ipp	15.12	V
Peak Pulse Current (10/1000µs)	27.8	A
Peak Pulse Power	400	W
Package Type	DO-214AC (SMA)	—
Mounting Type	Surface Mount	—
Operating Temperature Range	-65 to 150	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the SMAJ8.5 is determined by the following critical parameters:

Electrical Compatibility Criteria:

Reverse standoff voltage must equal 8.5V (typical)
Breakdown voltage minimum must fall within 9.4V to 9.44V range
Clamping voltage maximum must not exceed 18.7V
Peak pulse current capability must be ≥27.7A
Peak pulse power must be ≥400W
Unidirectional channel configuration (single channel)
Zener diode type classification

Mechanical Compatibility Criteria:

Package type: DO-214AC (SMA) surface mount
Mounting type: Surface mount
Operating temperature range must encompass at least -55°C to 150°C

Compliance Requirements:

ROHS3 compliant
Moisture sensitivity level MSL 1 (unlimited)

All substitute parts listed maintain these core parameters within acceptable engineering tolerances for direct functional replacement.

Parameter Comparison

Part Number	Manufacturer	Standoff Voltage (V)	Breakdown Min (V)	Clamp Voltage Max (V)	Peak Pulse Current (A)	Peak Pulse Power (W)	Temp Range (°C)	Product Status
SMAJ8.5	Littelfuse Inc.	8.5	8.93	15.12	27.8	400	-65 to 150	Obsolete
SMAJ8.5A	Meritek	8.5	9.44	14.4	27.78	400	-55 to 150	Active
SMA6J8.5A-TR	STMicroelectronics	8.5	9.4	18.7	205	600	-55 to 175	Active
SMAJ8.5A-13-F	Diodes Incorporated	8.5	9.44	14.4	27.7	400	-55 to 150	Active
SMAJ8.5A-TP	Micro Commercial Co	8.5	9.44	14.4	27.7	400	-55 to 175	Active
SMAJ8.5AE3/TR13	Microchip Technology	8.5	9.44	14.4	34.7	500	-65 to 150	Active
SMAJ8.5E3/TR13	Microchip Technology	8.5	9.44	15.9	31.4	500	-65 to 150	Active
TV04A8V5J-G	Comchip Technology	8.5	9.44	14.4	27.78	400	-55 to 150	Active

Engineering Selection Recommendations

All listed substitute parts are classified as active products with ROHS3 compliance and MSL 1 moisture sensitivity rating, ensuring regulatory alignment and supply chain availability.

Primary Substitutes (Closest Electrical Match): SMAJ8.5A (Meritek), SMAJ8.5A-13-F (Diodes Incorporated), and TV04A8V5J-G (Comchip Technology) provide direct functional equivalence with clamping voltages of 14.4V and peak pulse currents of 27.7–27.78A, matching the original specification within standard engineering tolerances.

Extended Temperature Range Options: SMAJ8.5A-TP (Micro Commercial Co) extends the upper operating temperature to 175°C while maintaining identical electrical parameters, suitable for applications requiring enhanced thermal performance.

Enhanced Performance Alternatives: SMAJ8.5AE3/TR13 and SMAJ8.5E3/TR13 (Microchip Technology) offer increased peak pulse current (31.4–34.7A) and power dissipation (500W), providing design margin for applications with higher transient stress. SMAJ8.5AE3/TR13 maintains the original -65°C lower temperature limit.

High-Current Application: SMA6J8.5A-TR (STMicroelectronics) delivers significantly elevated peak pulse current (205A at 8/20µs) and power (600W) with extended temperature range (-55 to 175°C), appropriate for high-energy transient suppression requirements.

Frequently Asked Questions (FAQ)

Q: Can SMAJ8.5A directly replace the obsolete SMAJ8.5? A: Yes. SMAJ8.5A maintains the 8.5V standoff voltage, 14.4V clamping voltage, and 27.78A peak pulse current within acceptable engineering tolerances. The primary difference is the reduced lower operating temperature limit (-55°C versus -65°C). Verify application temperature requirements before selection.

Q: What is the difference between SMAJ8.5A and SMAJ8.5A-TP? A: Both parts share identical electrical specifications (8.5V standoff, 14.4V clamp, 27.7A peak current). SMAJ8.5A-TP extends the upper operating temperature to 175°C compared to 150°C for SMAJ8.5A. Select SMAJ8.5A-TP for high-temperature applications.

Q: Why does SMA6J8.5A-TR have significantly higher peak pulse current? A: SMA6J8.5A-TR is rated for 205A peak pulse current (8/20µs measurement) versus 27.8A (10/1000µs) for SMAJ8.5. This reflects different pulse waveform specifications and higher energy dissipation capability (600W). Use this part only when application transient energy exceeds standard SMAJ8.5 ratings.

Q: Are all substitute parts in the same DO-214AC (SMA) package? A: Yes. All listed substitutes use the DO-214AC (SMA) surface-mount package, ensuring mechanical and PCB layout compatibility with the original SMAJ8.5.

Q: Do all substitutes meet RoHS3 compliance? A: Yes. All active substitute parts listed are ROHS3 compliant with MSL 1 moisture sensitivity rating, meeting current regulatory and supply chain requirements.

Q: Which substitute offers the closest temperature range match to the original SMAJ8.5? A: SMAJ8.5AE3/TR13 and SMAJ8.5E3/TR13 (Microchip Technology) maintain the original -65°C lower operating limit, providing the closest thermal specification match while offering enhanced current and power ratings.

Q: What packaging formats are available for these substitutes? A: Substitutes are supplied in Tape & Reel (TR), Cut Tape (CT) with Digi-Reel, or standard packaging configurations. Verify packaging requirements with your procurement specification before ordering.

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