1SMB5945 R5G Equivalent & Substitute Parts

Part Overview

The 1SMB5945 R5G is a surface mount Zener diode manufactured by Taiwan Semiconductor Corporation, rated for 68 V nominal Zener voltage with 3 W maximum power dissipation in a DO-214AA (SMB) package. This part is discontinued at DiGi Electronics, necessitating identification of equivalent and substitute components for ongoing design requirements and production needs. Equivalent parts maintain identical electrical specifications, while substitute parts offer similar functionality with variations in voltage, power rating, or manufacturer.

Key Parameters

Parameter	Value
Voltage - Zener (Nom)	68 V
Tolerance	±5%
Power - Max	3 W
Impedance (Max)	120 Ohms
Current - Reverse Leakage @ Vr	1 µA @ 51.7 V
Operating Temperature	-55°C ~ 150°C
Package / Case	DO-214AA, SMB
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of Zener diodes is determined by the following critical parameters: nominal Zener voltage (Vz), maximum power dissipation (P-Max), impedance (Zzt), reverse leakage current, operating temperature range, and package type. Parts are grouped into three categories:

Parametric Equivalents maintain all electrical specifications identical to the main part (68 V, 3 W, 120 Ohms impedance, 1 µA reverse leakage). These parts differ only in packaging format (Tape & Reel versus other configurations) or product status (Active versus Discontinued).

Direct Manufacturer Equivalents are sourced from alternative manufacturers (Vishay) and maintain identical electrical parameters (68 V, 3 W, 120 Ohms, 1 µA reverse leakage) with the same DO-214AA package, ensuring pin-for-pin and functional compatibility.

Upgrade Parts provide enhanced specifications, such as extended operating temperature range (-65°C to 150°C versus -55°C to 150°C) or higher inventory availability, while maintaining core electrical parameters.

Similar Parts offer alternative voltage ratings (62 V or 60 V) or power ratings (5 W or 550 mW) and are suitable only when circuit design permits voltage or power tolerance variations.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	P-Max	Zzt (Max)	Reverse Leakage	Temp Range	Package	Product Status
1SMB5945 R5G	Taiwan Semiconductor	68 V	±5%	3 W	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMB)	Discontinued
1SMB5945	Taiwan Semiconductor	68 V	±5%	3 W	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMB)	Active
1SMB5945H	Taiwan Semiconductor	68 V	±5%	3 W	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMB)	Active (AEC-Q101)
SMBZ5945B-E3/52	Vishay	68 V	±5%	3 W	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMBJ)	Active
SMBZ5945B-E3/5B	Vishay	68 V	±5%	3 W	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMBJ)	Active
1SMB5945BT3G	onsemi	68 V	±5%	3 W	120 Ω	1 µA @ 51.7 V	-65°C ~ 150°C	DO-214AA (SMB)	Active
1SMB5944BT3G	onsemi	62 V	±5%	3 W	100 Ω	1 µA @ 47.1 V	-65°C ~ 150°C	DO-214AA (SMB)	Active
SMBJ5371B-TP	Micro Commercial Co	60 V	±5%	5 W	40 Ω	500 nA @ 45.5 V	-55°C ~ 150°C	DO-214AA (SMB)	Active
SMBJ5372B-TP	Micro Commercial Co	62 V	±5%	5 W	42 Ω	500 nA @ 47.1 V	-55°C ~ 150°C	DO-214AA (SMB)	Active
SMBZ5945B-M3/52	Vishay	68 V	±5%	550 mW	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMBJ)	Active
SMBZ5945B-M3/5B	Vishay	68 V	±5%	550 mW	120 Ω	1 µA @ 51.7 V	-55°C ~ 150°C	DO-214AA (SMBJ)	Active

Engineering Selection Recommendations

For Direct Replacement (Identical Specifications):

Select 1SMB5945 (Taiwan Semiconductor, Active status) or 1SMB5945H (Taiwan Semiconductor, Active status with AEC-Q101 automotive qualification) when exact electrical and thermal specifications are required. Both parts maintain 68 V nominal Zener voltage, 3 W power rating, 120 Ohms impedance, and -55°C to 150°C operating range. The 1SMB5945H variant is qualified to AEC-Q101 automotive standards and is suitable for applications requiring automotive-grade components.

For Cross-Manufacturer Equivalents:

SMBZ5945B-E3/52 and SMBZ5945B-E3/5B (Vishay) provide identical electrical specifications with active product status and ROHS3 compliance. These parts are suitable for applications where manufacturer diversification is required for supply chain resilience.

For Enhanced Temperature Range:

1SMB5945BT3G (onsemi) extends the operating temperature range to -65°C to 150°C while maintaining all other electrical parameters. This part is suitable for applications requiring lower temperature operation and offers significantly higher inventory availability (20,864 units).

For Voltage or Power Variations:

1SMB5944BT3G (62 V, 3 W) is suitable only when circuit design permits a 6 V reduction in Zener voltage. SMBJ5371B-TP (60 V, 5 W) and SMBJ5372B-TP (62 V, 5 W) are suitable only when higher power dissipation capability is required and voltage tolerance is acceptable. SMBZ5945B-M3/52 and SMBZ5945B-M3/5B (550 mW) are suitable only for applications with reduced power requirements.

Compliance Considerations:

All listed parts maintain ROHS3 compliance, Moisture Sensitivity Level 1 (Unlimited), and REACH Unaffected status, ensuring regulatory compatibility with the original part.

Frequently Asked Questions (FAQ)

Q: Can 1SMB5945 directly replace 1SMB5945 R5G?

A: Yes. The 1SMB5945 is a parametric equivalent with identical electrical specifications (68 V, 3 W, 120 Ohms impedance, 1 µA reverse leakage, -55°C to 150°C operating range) and DO-214AA package. The primary difference is product status: 1SMB5945 R5G is discontinued, while 1SMB5945 is active.

Q: What is the difference between 1SMB5945H and 1SMB5945?

A: Both parts are parametrically identical with 68 V nominal voltage, 3 W power rating, and identical impedance and leakage specifications. The 1SMB5945H carries AEC-Q101 automotive qualification, making it suitable for automotive applications requiring qualified components.

Q: Can Vishay SMBZ5945B-E3/52 replace the Taiwan Semiconductor part?

A: Yes. SMBZ5945B-E3/52 maintains identical electrical specifications (68 V, 3 W, 120 Ohms, 1 µA reverse leakage) and DO-214AA package configuration. The difference is manufacturer (Vishay versus Taiwan Semiconductor). Both are ROHS3 compliant and active products.

Q: Is 1SMB5945BT3G a suitable replacement?

A: Yes, with an enhancement. 1SMB5945BT3G (onsemi) maintains all electrical specifications identical to the original part but extends the operating temperature range to -65°C (versus -55°C minimum). This part is suitable for applications requiring lower temperature operation and offers superior inventory availability.

Q: Can I use 1SMB5944BT3G as a substitute?

A: 1SMB5944BT3G is a similar part with a different Zener voltage (62 V versus 68 V) and impedance (100 Ohms versus 120 Ohms). This part is suitable only when circuit design permits a 6 V reduction in Zener voltage and the corresponding impedance change.

Q: What is the difference between SMBJ5371B-TP and the original part?

A: SMBJ5371B-TP differs in three parameters: Zener voltage (60 V versus 68 V), power rating (5 W versus 3 W), and impedance (40 Ohms versus 120 Ohms). This part is suitable only when higher power dissipation is required and the lower Zener voltage is acceptable for the application.

Q: Are the Vishay SMBZ5945B-M3 variants suitable replacements?

A: SMBZ5945B-M3/52 and SMBZ5945B-M3/5B maintain the 68 V Zener voltage and 120 Ohms impedance but reduce power rating to 550 mW (versus 3 W). These parts are suitable only for applications with reduced power dissipation requirements.

Q: Do all substitute parts have the same package?

A: All listed parts use DO-214AA (SMB) package configuration, ensuring mechanical and pin compatibility. Supplier device package designations may vary (SMB, SMBJ) but refer to the same physical package standard.

Q: Which part offers the best inventory availability?

A: 1SMB5945BT3G (onsemi) offers the highest inventory availability at 20,864 units, combined with extended temperature range (-65°C to 150°C) and identical electrical specifications to the original part.

Q: Are all parts ROHS3 compliant?

A: Yes. All listed equivalent and substitute parts maintain ROHS3 compliance, Moisture Sensitivity Level 1 (Unlimited), and REACH Unaffected status.

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