1SMB48AT3G Equivalent & Substitute Parts

Part Overview

The 1SMB48AT3G is a transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. This component features a 48V reverse standoff voltage with a 77.4V maximum clamping voltage and 7.7A peak pulse current capability in a DO-214AA (SMB) package. The part is currently classified as obsolete, necessitating identification of active equivalent and substitute components that maintain electrical and mechanical compatibility for ongoing production and field replacement requirements.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	48	V
Voltage - Breakdown (Min)	53.3	V
Voltage - Clamping (Max) @ Ipp	77.4	V
Current - Peak Pulse (10/1000µs)	7.7	A
Power - Peak Pulse	600	W
Package / Case	DO-214AA, SMB	—
Operating Temperature Range	-65°C to 150°C	TJ
Type	Zener	—
Unidirectional Channels	1	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the 1SMB48AT3G is determined by strict electrical and mechanical parameter matching:

Primary Substitution Criteria:

Voltage - Reverse Standoff: 48V (exact match required)
Voltage - Clamping (Max) @ Ipp: 77.4V (exact match required)
Current - Peak Pulse (10/1000µs): 7.7A ±0.4A tolerance acceptable
Package / Case: DO-214AA, SMB (mechanical compatibility)
Power - Peak Pulse: 600W (minimum requirement)
Unidirectional Channels: 1 (functional requirement)

Secondary Compatibility Parameters:

Operating Temperature Range: -65°C to 150°C minimum
RoHS3 Compliance: Required
MSL Rating: 1 (Unlimited) preferred

Parts are grouped into two categories:

Group A - Direct Electrical Equivalents (77.4V Clamping): SMBJ48A (Meritek), SMBJ48A-HR (Littelfuse), SMBJ48A-HRA (Littelfuse), SMBJ48A-13-F (Diodes Incorporated), SMBJ48A-TP (Micro Commercial Co), SMBJ48A-TR (STMicroelectronics), SMBJ48AE3/TR13 (Microchip Technology)

Group B - Voltage-Variant Substitute: SMBJ48E3/TR13 (Microchip Technology) features 85.5V clamping voltage and is suitable only where higher clamping voltage is acceptable within system design margins.

Group C - Voltage-Reduced Substitute: SMBJ45A (MDD) operates at 45V reverse standoff with 72.7V clamping and is suitable only where lower voltage rating meets application requirements.

Parameter Comparison

Part Number	Manufacturer	VWM (V)	VBR Min (V)	VC Max @ Ipp (V)	Ipp (A)	Temp Range (°C)	Status
1SMB48AT3G	Littelfuse Inc.	48	53.3	77.4	7.7	-65 to 150	Obsolete
SMBJ48A	Meritek	48	53.3	77.4	7.75	-55 to 150	Active
SMBJ48A-HR	Littelfuse Inc.	48	53.3	77.4	7.8	-65 to 150	Active
SMBJ48A-HRA	Littelfuse Inc.	48	53.3	77.4	7.8	-65 to 150	Active
SMBJ48A-13-F	Diodes Incorporated	48	53.3	77.4	7.7	-55 to 150	Active
SMBJ48A-TP	Micro Commercial Co	48	53.3	77.4	7.7	-55 to 175	Active
SMBJ48A-TR	STMicroelectronics	48	53.3	77.4	8.1	-55 to 150	Active
SMBJ48AE3/TR13	Microchip Technology	48	53.3	77.4	7.7	-65 to 150	Active
SMBJ48E3/TR13	Microchip Technology	48	53.3	85.5	7.0	-65 to 150	Active
SMBJ45A	MDD	45	50.0	72.7	8.3	-50 to 150	Active

Engineering Selection Recommendations

Preferred Direct Replacements (Group A):

For applications requiring exact electrical equivalence to the 1SMB48AT3G, select from active parts with matching 48V reverse standoff and 77.4V clamping specifications. SMBJ48A-HR and SMBJ48A-HRA (Littelfuse Inc.) maintain the original manufacturer lineage and support the full -65°C to 150°C operating range. SMBJ48AE3/TR13 (Microchip Technology) provides identical electrical performance with equivalent temperature range. All Group A substitutes are ROHS3 compliant with MSL 1 rating.

Temperature-Constrained Applications:

Where operating temperature range is limited to -55°C minimum or higher, SMBJ48A-13-F (Diodes Incorporated), SMBJ48A-TP (Micro Commercial Co), and SMBJ48A-TR (STMicroelectronics) are suitable. SMBJ48A-TP extends the upper temperature limit to 175°C, providing additional thermal margin in high-temperature environments.

Voltage-Variant Substitutes:

SMBJ48E3/TR13 (Microchip Technology) with 85.5V clamping voltage is suitable only where system design accommodates higher transient voltage suppression. SMBJ45A (MDD) with 45V reverse standoff and 72.7V clamping is suitable only where application requirements permit reduced voltage rating and minimum operating temperature of -50°C.

Inventory and Availability:

SMBJ48A (Meritek) offers the highest inventory availability at 77,400 units. SMBJ48A-HR and SMBJ48A-HRA maintain lower stock levels (1,062 and 725 units respectively) but provide direct Littelfuse sourcing continuity.

Frequently Asked Questions (FAQ)

Q: Can SMBJ48E3/TR13 replace 1SMB48AT3G directly?

A: SMBJ48E3/TR13 has identical reverse standoff voltage (48V) but features 85.5V clamping voltage versus 77.4V in the original part. This higher clamping voltage alters transient suppression characteristics. Use only where system design margins accommodate increased clamping voltage.

Q: What is the difference between SMBJ48A-HR and SMBJ48A-HRA?

A: Both parts share identical electrical specifications (48V standoff, 77.4V clamping, 7.8A peak pulse) and operating temperature range (-65°C to 150°C). The suffix designations indicate different packaging or tape configurations. Verify packaging requirements with supplier documentation before selection.

Q: Is SMBJ45A compatible with 1SMB48AT3G applications?

A: SMBJ45A operates at 45V reverse standoff with 72.7V clamping voltage, representing a 3V reduction in standoff voltage and 4.7V reduction in clamping voltage. Compatibility depends on application circuit design. Use only where lower voltage rating is explicitly acceptable within system protection requirements.

Q: Do all substitute parts meet RoHS3 compliance?

A: All listed substitute parts are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, matching the original 1SMB48AT3G specifications.

Q: What is the temperature range limitation for SMBJ45A?

A: SMBJ45A operates from -50°C to 150°C, providing a 15°C higher minimum temperature limit compared to the 1SMB48AT3G (-65°C to 150°C). Applications requiring operation below -50°C require selection from Group A substitutes.

Q: Are there packaging differences between substitute parts?

A: All substitute parts use DO-214AA (SMB) package for mechanical compatibility. Packaging format variations (Tape & Reel, Cut Tape, Digi-Reel) affect handling and assembly processes but not electrical or mechanical fit. Verify packaging format with procurement requirements.

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