1SMB45CAT3G Equivalent & Substitute Parts

Part Overview

The 1SMB45CAT3G 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 45V reverse standoff voltage with 72.2V maximum clamping voltage and 8.3A peak pulse current capability in a DO-214AA (SMB) package. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for new designs and production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	45	V
Voltage - Breakdown (Min)	50	V
Voltage - Clamping (Max) @ Ipp	72.2	V
Current - Peak Pulse (10/1000µs)	8.3	A
Power - Peak Pulse	600	W
Package / Case	DO-214AA, SMB	—
Mounting Type	Surface Mount	—
Operating Temperature	-65 to 150	°C (TJ)
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the 1SMB45CAT3G is determined by strict equivalence across the following electrical and mechanical parameters:

Voltage - Reverse Standoff: 45V (nominal)
Voltage - Breakdown: 50V (minimum)
Voltage - Clamping: 72.2V to 72.7V range acceptable
Current - Peak Pulse: 8.25A to 8.3A range acceptable
Power - Peak Pulse: 600W
Package: DO-214AA / SMB (surface mount)
Bidirectional Channels: 1
Type: Zener TVS Diode
Applications: General Purpose
RoHS Compliance: ROHS3 Compliant
MSL Rating: 1 (Unlimited)

Substitute parts must maintain all electrical specifications within the defined tolerances and use identical or functionally equivalent packaging. Operating temperature range variations are acceptable provided the minimum operating temperature does not exceed -55°C and maximum does not fall below 150°C.

Parameter Comparison

Part Number	Manufacturer	Status	VWM (V)	VBR (V)	VC (V)	Ipp (A)	Package	Temp Range (°C)
1SMB45CAT3G	Littelfuse Inc.	Obsolete	45	50	72.2	8.3	DO-214AA, SMB	-65 to 150
SMBJ45CA	MDD	Active	45	50	72.7	8.3	DO-214AA, SMB	-50 to 150
SMBJ45CA-HR	Littelfuse Inc.	Active	45	50	72.7	8.3	DO-214AA, SMB	-65 to 150
SMBJ45CA-HRA	Littelfuse Inc.	Active	45	50	72.7	8.3	DO-214AA, SMB	-65 to 150
TV06B450JB-G	Comchip Technology	Active	45	50	72.7	8.25	DO-214AA, SMB	Not specified
SMBJ45CA-13-F	Diodes Incorporated	Active	45	50	72.7	8.3	DO-214AA, SMB	-55 to 150
SMBJ45CA-TP	Micro Commercial Co	Active	45	50	72.7	8.3	DO-214AA, SMB	-55 to 175
SMBJ45CE3/TR13	Microchip Technology	Active	45	50	80.3	7.5	DO-214AA, SMB	-65 to 150
TV06B450JB-HF	Comchip Technology	Active	45	50	72.7	8.25	DO-214AA, SMB	Not specified

Engineering Selection Recommendations

All substitute parts listed are ROHS3 compliant and carry MSL rating 1 (Unlimited), matching the original 1SMB45CAT3G specifications. Selection among active alternatives should prioritize:

Primary Equivalents (Recommended): SMBJ45CA-HR and SMBJ45CA-HRA (Littelfuse Inc.) maintain identical electrical parameters and operating temperature range (-65 to 150°C) as the original part, ensuring direct functional replacement with active product status and established supply availability.

Secondary Equivalents: SMBJ45CA-13-F (Diodes Incorporated) and SMBJ45CA-TP (Micro Commercial Co) provide electrical equivalence with slightly narrower minimum operating temperatures (-55°C) but remain suitable for most general-purpose applications. SMBJ45CA-TP extends maximum operating temperature to 175°C, offering enhanced thermal margin.

Alternative Equivalent: SMBJ45CA (MDD) matches electrical specifications but operates to -50°C minimum, acceptable for applications not requiring extended low-temperature performance.

Limited Equivalence: SMBJ45CE3/TR13 (Microchip Technology) maintains voltage standoff and breakdown specifications but exhibits higher clamping voltage (80.3V) and reduced peak pulse current (7.5A), suitable only for applications with relaxed clamping voltage tolerance. TV06B450JB-G and TV06B450JB-HF (Comchip Technology) provide equivalent clamping voltage and current but lack specified operating temperature data, requiring verification for temperature-critical applications.

Frequently Asked Questions (FAQ)

Q: Can SMBJ45CE3/TR13 be used as a direct replacement for 1SMB45CAT3G?

A: SMBJ45CE3/TR13 is not a direct equivalent. While it maintains the 45V reverse standoff and 50V breakdown voltage, the clamping voltage reaches 80.3V (versus 72.2V) and peak pulse current is reduced to 7.5A (versus 8.3A). Use only if circuit design accommodates higher clamping voltage and lower current handling.

Q: Are all substitute parts available in the same SMB package?

A: Yes. All listed substitutes use DO-214AA (SMB) surface mount packaging, ensuring mechanical and footprint compatibility with the original 1SMB45CAT3G design.

Q: What is the difference between SMBJ45CA-HR and SMBJ45CA-HRA?

A: Both parts are manufactured by Littelfuse Inc. with identical electrical specifications and operating temperature range. The designation difference reflects internal product line categorization. Both are functionally equivalent for substitution purposes.

Q: Which substitute offers the widest operating temperature range?

A: SMBJ45CA-TP (Micro Commercial Co) extends to 175°C maximum operating temperature, compared to 150°C for most alternatives. This provides additional thermal margin for high-temperature environments while maintaining -55°C minimum operating temperature.

Q: Is the clamping voltage difference between 72.2V and 72.7V significant?

A: The 0.5V difference falls within normal manufacturing tolerance for TVS diodes and does not affect functional equivalence for general-purpose overvoltage protection applications. Both values meet the specified electrical performance window.

Q: Can I use parts with unspecified operating temperature ranges?

A: TV06B450JB-G and TV06B450JB-HF lack published operating temperature specifications. Verification with the manufacturer is required before use in temperature-critical applications or designs requiring documented thermal performance.

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