SD845-T Schottky Diode Equivalent & Substitute Parts

Part Overview

The SD845-T is a Schottky rectifier diode manufactured by Diodes Incorporated, rated for 45 V DC reverse voltage and 8 A average rectified current in a DO-201AD through-hole axial package. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and production continuity. Substitute parts are selected based on matching or exceeding the electrical performance parameters and mechanical compatibility of the original component.

Key Parameters

Parameter	SD845-T Value
Voltage - DC Reverse (Vr) (Max)	45 V
Current - Average Rectified (Io)	8 A
Voltage - Forward (Vf) (Max) @ If	550 mV @ 8 A
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)
Current - Reverse Leakage @ Vr	1 mA @ 45 V
Capacitance @ Vr, F	550pF @ 4V, 1MHz
Mounting Type	Through Hole
Package / Case	DO-201AD, Axial
Operating Temperature - Junction	-65°C ~ 150°C
Technology	Schottky
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the SD845-T are categorized based on electrical parameter compatibility and mechanical form factor. The primary substitution criteria are:

Critical Parameters for Substitution:

Voltage - DC Reverse (Vr) (Max): 45 V minimum
Current - Average Rectified (Io): 8 A minimum
Technology: Schottky
Mounting Type: Through Hole
Package / Case: DO-201AD or equivalent axial configuration

Substitution Groups:

Group 1: Direct Electrical and Package Match (45 V, 8 A, DO-201AD) Parts SR8045-AP, SR8045-BP, and SR8045-TP from Micro Commercial Co provide identical voltage and current ratings with DO-201AD packaging. These parts are active products with full compliance documentation.

Group 2: Equivalent Voltage and Current with Alternative Packaging (45 V, 8 A, Axial) The onsemi 80SQ045NG and 80SQ045NRLG offer 45 V and 8 A ratings in axial through-hole configuration with DO-201AA or DO-27 package designations, functionally equivalent to DO-201AD.

Group 3: Elevated Current Rating (45 V, 10 A) The SR1045-AP from Micro Commercial Co provides 45 V reverse voltage with 10 A current capacity, exceeding the original 8 A specification while maintaining 45 V rating and through-hole mounting.

Group 4: Reduced Voltage Rating (40 V, 8 A, DO-201AD) Parts SR804-AP, SR804-BP, and SR804-TP are rated for 40 V reverse voltage with 8 A current in DO-201AD packaging. These parts are suitable for applications where 40 V reverse voltage is acceptable.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vr (Max)	Io	Vf (Max) @ If	Package / Case	Operating Temp (Junction)	Product Status	Inventory (Pcs)
SD845-T	Diodes Incorporated	45 V	8 A	550 mV @ 8 A	DO-201AD, Axial	-65°C ~ 150°C	Obsolete	1080
80SQ045NG	onsemi	45 V	8 A	550 mV @ 8 A	DO-201AA, DO-27, Axial	-65°C ~ 175°C	Active	1384
80SQ045NRLG	onsemi	45 V	8 A	550 mV @ 8 A	DO-201AA, DO-27, Axial	-65°C ~ 125°C	Active	8200
SR1045-AP	Micro Commercial Co	45 V	10 A	550 mV @ 10 A	R-6, Axial	-55°C ~ 150°C	Active	823
SR804-AP	Micro Commercial Co	40 V	8 A	650 mV @ 8 A	DO-201AD, Axial	-55°C ~ 125°C	Active	692
SR804-BP	Micro Commercial Co	40 V	8 A	650 mV @ 8 A	DO-201AD, Axial	-55°C ~ 125°C	Active	926
SR804-TP	Micro Commercial Co	40 V	8 A	650 mV @ 8 A	DO-201AD, Axial	-55°C ~ 125°C	Active	1112
SR8045-AP	Micro Commercial Co	45 V	8 A	650 mV @ 8 A	DO-201AD, Axial	-55°C ~ 125°C	Active	872
SR8045-BP	Micro Commercial Co	45 V	8 A	650 mV @ 8 A	DO-201AD, Axial	-55°C ~ 125°C	Active	838
SR8045-TP	Micro Commercial Co	45 V	8 A	650 mV @ 8 A	DO-201AD, Axial	-55°C ~ 125°C	Active	742

Engineering Selection Recommendations

Primary Substitutes (Recommended for Direct Replacement):

The onsemi 80SQ045NG and 80SQ045NRLG are the preferred substitutes for the obsolete SD845-T. Both parts maintain the 45 V reverse voltage and 8 A current specifications with identical forward voltage characteristics (550 mV @ 8 A). The 80SQ045NRLG offers superior inventory availability (8200 units) and is supplied in Cut Tape packaging. Both parts are ROHS3 compliant and active products with extended operating temperature ranges compared to the original component.

Secondary Substitutes (Matching Voltage and Current):

The Micro Commercial Co SR8045-AP, SR8045-BP, and SR8045-TP series provide exact voltage (45 V) and current (8 A) matching in DO-201AD packaging. These parts are active products with REACH compliance. The forward voltage specification is 650 mV @ 8 A, representing a 100 mV increase over the original SD845-T. Operating temperature range is -55°C to 125°C, narrower than the original -65°C to 150°C specification.

Alternative Substitutes (Elevated Current Capability):

The SR1045-AP from Micro Commercial Co provides 45 V reverse voltage with elevated 10 A current capacity. This part is suitable for applications requiring additional current margin. The R-6 package is mechanically compatible with through-hole mounting requirements.

Conditional Substitutes (Reduced Voltage Rating):

The SR804-AP, SR804-BP, and SR804-TP series are rated for 40 V reverse voltage with 8 A current. These parts are suitable only for applications where the circuit design accommodates 40 V maximum reverse voltage. Forward voltage is specified at 650 mV @ 8 A.

Frequently Asked Questions (FAQ)

Q: Can the onsemi 80SQ045NG directly replace the SD845-T in existing designs?

A: Yes. The 80SQ045NG maintains identical electrical specifications (45 V, 8 A, 550 mV forward voltage) and through-hole axial mounting. The DO-201AA and DO-27 package designations are functionally equivalent to the original DO-201AD. Physical dimensions and lead spacing are compatible with existing PCB layouts.

Q: What is the difference between the onsemi 80SQ045NG and 80SQ045NRLG?

A: Both parts have identical electrical specifications. The primary differences are packaging format (80SQ045NG supplied in Bulk; 80SQ045NRLG supplied in Cut Tape) and operating temperature range (80SQ045NG: -65°C to 175°C; 80SQ045NRLG: -65°C to 125°C). The 80SQ045NRLG offers significantly higher inventory availability.

Q: Why do the Micro Commercial Co SR8045 series parts have higher forward voltage (650 mV) compared to the original SD845-T (550 mV)?

A: Forward voltage variation is a normal characteristic of Schottky diodes and reflects differences in semiconductor processing and junction design between manufacturers. The 100 mV difference is within typical manufacturing tolerances for this device category. Circuit designs must account for this variation in thermal and voltage drop calculations.

Q: Are the SR804 series parts (40 V rating) suitable replacements for the SD845-T (45 V rating)?

A: The SR804 series is suitable only for applications where the maximum reverse voltage requirement is 40 V or lower. If the circuit design requires 45 V reverse voltage capability, the SR804 series is not appropriate. The SR8045 series maintains the 45 V specification.

Q: What is the significance of the different suffixes (AP, BP, TP) on the Micro Commercial Co parts?

A: The suffixes indicate different packaging or tape configurations within the same electrical specification. All SR8045-AP, SR8045-BP, and SR8045-TP variants provide identical electrical performance (45 V, 8 A, 650 mV forward voltage) and are mechanically compatible.

Q: Is the SR1045-AP with 10 A current rating a suitable substitute for the 8 A SD845-T?

A: Yes. The SR1045-AP provides 45 V reverse voltage with elevated 10 A current capacity, exceeding the original 8 A specification. This part is suitable for applications where additional current margin is beneficial. The R-6 package is mechanically compatible with through-hole mounting.

Q: What compliance certifications apply to the substitute parts?

A: The onsemi 80SQ045NG and 80SQ045NRLG are ROHS3 compliant. The Micro Commercial Co SR series parts (SR1045-AP, SR804 series, SR8045 series) are REACH unaffected. All parts are classified under ECCN EAR99 and HTSUS 8541.10.0080.

Q: How do the operating temperature ranges compare between the original and substitute parts?

A: The SD845-T operates from -65°C to 150°C. The onsemi 80SQ045NG extends to 175°C. The 80SQ045NRLG and all Micro Commercial Co parts operate from -55°C to 125°C, representing a narrower range at the lower temperature limit. Circuit designs operating below -55°C require the onsemi 80SQ045NG or original SD845-T.

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