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1SMB51AT3 Equivalent & Substitute Parts
Part Overview
The 1SMB51AT3 is a unidirectional transient voltage suppressor (TVS) diode manufactured by onsemi, designed for general-purpose overvoltage protection applications. This component features a 51V reverse standoff voltage with an 82.4V maximum clamping voltage and 7.3A peak pulse current capability in a surface-mount SMB (DO-214AA) package. The part is currently classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.
Substiute Parts
Key Parameters
| Parameter | Value | Unit |
|---|---|---|
| Manufacturer | onsemi | — |
| Part Number | 1SMB51AT3 | — |
| Product Status | Obsolete | — |
| Type | Zener TVS Diode | — |
| Voltage - Reverse Standoff (Typ) | 51 | V |
| Voltage - Breakdown (Min) | 56.7 | V |
| Voltage - Clamping (Max) @ Ipp | 82.4 | V |
| Current - Peak Pulse (10/1000µs) | 7.3 | A |
| Power - Peak Pulse | 600 | W |
| Package / Case | DO-214AA, SMB | — |
| Operating Temperature Range | -65 to 150 | °C (TJ) |
| RoHS Status | Non-compliant | — |
| Moisture Sensitivity Level | 1 (Unlimited) | — |
Substitute Part Grouping Explanation
Substitution of the 1SMB51AT3 is determined by strict electrical and mechanical parameter matching:
Critical Matching Parameters:
- Voltage - Reverse Standoff (Typ): 51V
- Voltage - Clamping (Max) @ Ipp: 82.4V
- Current - Peak Pulse (10/1000µs): 7.3A
- Power - Peak Pulse: 600W
- Package / Case: DO-214AA (SMB) or equivalent surface-mount package
- Unidirectional configuration (single channel)
Substitute Categories:
Direct Electrical Equivalents (Identical Parameters): Parts matching all critical electrical specifications with identical or superior operating temperature ranges and active product status.
Similar Electrical Equivalents (Minor Parameter Variance): Parts with slight deviations in voltage or current ratings that remain within functional tolerance for general-purpose protection applications.
Package Variants: Parts with identical electrical specifications but different surface-mount package designations (SOD-128 vs. DO-214AA).
Parameter Comparison
| Part Number | Manufacturer | Voltage - Reverse Standoff (V) | Voltage - Clamping (V) | Current - Peak Pulse (A) | Power - Peak Pulse (W) | Package | Operating Temp (°C) | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|---|---|
| 1SMB51AT3 | onsemi | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -65 to 150 | Obsolete | Non-compliant |
| SMBJ51A | Good-Ark Semiconductor | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -55 to 150 | Active | ROHS3 Compliant |
| PTVS51VP1UP,115 | NXP USA Inc. | 51 | 82.4 | 7.3 | 600 | SOD-128 | -55 to 150 | Active | Not specified |
| SMBJ48CA-TP | Micro Commercial Co | 48 | 77.4 | 7.7 | 600 | DO-214AA (SMB) | -55 to 175 | Active | ROHS3 Compliant |
| SMBJ51A-13-F | Diodes Incorporated | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -55 to 150 | Active | ROHS3 Compliant |
| SMBJ51A-HR | Littelfuse Inc. | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -65 to 150 | Active | ROHS3 Compliant |
| SMBJ51A-HRA | Littelfuse Inc. | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -65 to 150 | Active | ROHS3 Compliant |
| SMBJ51A-TP | Micro Commercial Co | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -55 to 175 | Active | ROHS3 Compliant |
| SMBJ51AE3/TR13 | Microchip Technology | 51 | 82.4 | 7.3 | 600 | DO-214AA (SMB) | -65 to 150 | Active | ROHS3 Compliant |
Engineering Selection Recommendations
Tier 1 - Direct Replacements (Identical Electrical Specifications):
SMBJ51A (Good-Ark Semiconductor), SMBJ51A-13-F (Diodes Incorporated), SMBJ51A-TP (Micro Commercial Co), SMBJ51A-HR (Littelfuse Inc.), SMBJ51A-HRA (Littelfuse Inc.), and SMBJ51AE3/TR13 (Microchip Technology) provide complete electrical equivalence to the 1SMB51AT3. All are active products with ROHS3 compliance, addressing the obsolescence of the original part. Selection among these options depends on supply chain availability and packaging format (Tape & Reel vs. Cut Tape).
Tier 2 - Extended Temperature Range:
SMBJ51A-HR and SMBJ51A-HRA (Littelfuse Inc.) maintain the original -65°C to 150°C operating temperature range, matching the 1SMB51AT3 specification exactly. These are preferred for applications requiring the full temperature envelope.
Tier 3 - Enhanced Temperature Performance:
SMBJ51A-TP (Micro Commercial Co) extends the upper operating temperature to 175°C, providing additional thermal margin for high-ambient applications while maintaining all electrical specifications.
Tier 4 - Alternative Package:
PTVS51VP1UP,115 (NXP USA Inc.) offers identical electrical performance in SOD-128 package format. This option is suitable only if PCB layout accommodates the different package footprint.
Tier 5 - Similar Electrical Performance:
SMBJ48CA-TP (Micro Commercial Co) provides a lower voltage alternative (48V standoff, 77.4V clamping) with slightly higher peak pulse current (7.7A) and extended temperature range (-55°C to 175°C). This part is suitable only for applications where the lower voltage rating is acceptable.
Frequently Asked Questions (FAQ)
Q: Can SMBJ51A directly replace 1SMB51AT3 without circuit modification?
A: Yes. SMBJ51A matches all critical electrical parameters: 51V reverse standoff, 82.4V clamping voltage, 7.3A peak pulse current, and 600W peak power. Both use DO-214AA (SMB) surface-mount packaging. The only difference is product status (SMBJ51A is active; 1SMB51AT3 is obsolete) and RoHS compliance (SMBJ51A is ROHS3 compliant).
Q: What is the difference between SMBJ51A-HR and SMBJ51A-HRA?
A: Both parts are manufactured by Littelfuse Inc. with identical electrical specifications and operating temperature range (-65°C to 150°C). The "-HR" and "-HRA" designations indicate different product series within Littelfuse's portfolio. Selection between them depends on supply availability and internal part numbering requirements.
Q: Why is SMBJ48CA-TP listed as a substitute if the voltage rating is different?
A: SMBJ48CA-TP is classified as a similar electrical equivalent rather than a direct replacement. It provides lower voltage protection (48V standoff vs. 51V) with marginally higher current handling (7.7A vs. 7.3A). This part is suitable only for applications where the lower voltage threshold is functionally acceptable.
Q: Does the package format affect substitution compatibility?
A: Package format is critical for PCB compatibility. All recommended Tier 1 and Tier 2 substitutes use DO-214AA (SMB) packaging, matching the 1SMB51AT3 footprint exactly. PTVS51VP1UP,115 uses SOD-128 packaging and requires PCB layout verification before selection.
Q: Are all substitute parts RoHS compliant?
A: All active substitute parts listed are ROHS3 compliant. The original 1SMB51AT3 is RoHS non-compliant. If RoHS compliance is a design requirement, any active substitute part satisfies this criterion.
Q: What is the inventory status of substitute parts?
A: SMBJ51A (Good-Ark Semiconductor) has the highest inventory availability at 17,300 pieces. SMBJ51A-TP and SMBJ51A-13-F maintain 3,311 and 15,200 pieces respectively. Littelfuse variants (SMBJ51A-HR and SMBJ51A-HRA) have lower stock levels (1,137 and 1,050 pieces). PTVS51VP1UP,115 (NXP) maintains 40,725 pieces in bulk packaging.
Q: Can SMBJ51A-TP be used in applications requiring the full -65°C to 150°C temperature range?
A: SMBJ51A-TP operates from -55°C to 175°C. While the upper limit exceeds the original specification, the lower limit (-55°C) does not reach -65°C. For applications requiring operation below -55°C, SMBJ51A-HR, SMBJ51A-HRA, or SMBJ51AE3/TR13 are required.
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