BAY73TR Equivalent & Substitute Parts

Part Overview

The BAY73TR is a general-purpose rectifier diode manufactured by onsemi, rated for 125 V DC reverse voltage and 500 mA average rectified current in a DO-35 through-hole package. This component is classified as obsolete, necessitating identification of equivalent alternatives for ongoing design and maintenance applications. Substitute parts must maintain functional compatibility within the specified electrical and mechanical parameters while accounting for differences in voltage rating, current capacity, and recovery characteristics.

Key Parameters

Parameter	BAY73TR Value	Unit
Voltage - DC Reverse (Vr) (Max)	125	V
Current - Average Rectified (Io)	500	mA
Voltage - Forward (Vf) (Max) @ If	1 @ 200	V @ mA
Reverse Recovery Time (trr)	1	µs
Current - Reverse Leakage @ Vr	5 @ 100	nA @ V
Capacitance @ Vr, F	8 @ 0, 1MHz	pF @ V, MHz
Mounting Type	Through Hole	-
Package / Case	DO-204AH, DO-35, Axial	-
Operating Temperature - Junction (Max)	175	°C
Product Status	Obsolete	-
Technology	Standard	-

Substitute Part Grouping Explanation

Substitution of the BAY73TR is determined by the following critical parameters:

Voltage Rating Compatibility: The substitute part must support the maximum DC reverse voltage (Vr) required by the application. The BAY73TR operates at 125 V; substitutes with lower voltage ratings (such as 75 V) are suitable only for applications with reduced voltage requirements, while substitutes with higher ratings (such as 225 V) provide additional margin.

Current Capacity: The BAY73TR carries 500 mA average rectified current. Substitute parts with lower current ratings (200 mA) are compatible only in circuits where the actual current demand does not exceed the substitute's specification.

Package and Mounting: Both the main part and substitutes use DO-35 through-hole axial packages, ensuring mechanical and electrical compatibility on printed circuit boards designed for this form factor.

Recovery Characteristics: The BAY73TR exhibits standard recovery behavior (>500 ns) with a reverse recovery time of 1 µs. Substitutes classified as small-signal diodes with faster recovery times (4 ns) are electrically compatible but represent different performance classes.

Temperature Range: The BAY73TR operates to 175°C junction temperature. Substitutes with equivalent or extended temperature ranges maintain thermal compatibility.

The identified substitutes—1N4448 and 1N5196—share the DO-35 package and through-hole mounting but differ in voltage and current ratings, requiring application-specific evaluation.

Parameter Comparison

Parameter	BAY73TR	1N4448	1N5196	Unit
Voltage - DC Reverse (Vr) (Max)	125	75	225	V
Current - Average Rectified (Io)	500	200	200	mA
Voltage - Forward (Vf) (Max) @ If	1 @ 200	1 @ 100	1 @ 100	V @ mA
Reverse Recovery Time (trr)	1	4	-	µs / ns
Current - Reverse Leakage @ Vr	5 @ 100	25 @ 20	25 @ 225	nA @ V
Mounting Type	Through Hole	Through Hole	Through Hole	-
Package / Case	DO-35	DO-35	DO-35	-
Operating Temperature - Junction	175 (Max)	-65 ~ 150	-65 ~ 175	°C
Product Status	Obsolete	Discontinued at DiGi Electronics	Active	-
Technology	Standard	Standard	Standard	-

Engineering Selection Recommendations

1N5196 Selection: The 1N5196 is the preferred substitute for new designs and long-term availability. This part maintains active product status, supports the full 175°C junction temperature range of the BAY73TR, and provides a higher voltage rating (225 V) suitable for applications requiring the BAY73TR's 125 V specification. The 1N5196 carries 200 mA current capacity, which is lower than the BAY73TR's 500 mA rating; selection requires confirmation that circuit current demands do not exceed 200 mA. The 1N5196 is RoHS non-compliant and REACH unaffected, matching the BAY73TR's compliance profile.

1N4448 Selection: The 1N4448 is a secondary alternative with discontinued status at DiGi Electronics. This part operates at a reduced voltage rating (75 V) and current capacity (200 mA), limiting its application to circuits with correspondingly reduced electrical demands. The 1N4448 operates to 150°C maximum junction temperature, below the BAY73TR's 175°C specification. The 1N4448 exhibits faster recovery characteristics (4 ns) compared to the BAY73TR (1 µs), representing a different performance class suitable for high-frequency applications. RoHS non-compliance matches the BAY73TR.

Compliance Considerations: Both substitutes maintain REACH unaffected status and EAR99 export classification consistent with the BAY73TR. Moisture sensitivity level remains at MSL 1 (unlimited) across all parts.

Frequently Asked Questions (FAQ)

Q: Can the 1N4448 directly replace the BAY73TR in all applications?

A: No. The 1N4448 operates at 75 V maximum reverse voltage and 200 mA current capacity, compared to the BAY73TR's 125 V and 500 mA ratings. Direct substitution is limited to circuits where the actual operating voltage does not exceed 75 V and current does not exceed 200 mA. Applications requiring the full 125 V or 500 mA specification require the 1N5196 or continued sourcing of BAY73TR inventory.

Q: Is the 1N5196 suitable for all BAY73TR applications?

A: The 1N5196 is suitable for applications where circuit current does not exceed 200 mA. The 1N5196's 225 V rating exceeds the BAY73TR's 125 V specification, providing additional voltage margin. The 1N5196 maintains the full 175°C junction temperature range and active product status, making it the preferred long-term substitute. Circuits requiring the BAY73TR's 500 mA capacity cannot use the 1N5196.

Q: Do all three parts use the same package?

A: Yes. The BAY73TR, 1N4448, and 1N5196 all use the DO-35 through-hole axial package (DO-204AH). Physical and electrical board compatibility is maintained across all three parts.

Q: What is the difference between standard recovery and small-signal recovery characteristics?

A: The BAY73TR exhibits standard recovery behavior with a reverse recovery time of 1 µs, suitable for general-purpose rectification. The 1N4448 is classified as a small-signal diode with 4 ns recovery time, enabling operation at higher switching frequencies. Selection between these recovery classes depends on circuit frequency requirements; standard recovery is appropriate for line-frequency and low-frequency applications, while small-signal recovery is required for high-frequency switching circuits.

Q: Are there temperature range differences between the substitutes?

A: Yes. The BAY73TR operates to 175°C maximum junction temperature. The 1N4448 operates to 150°C maximum, reducing the available thermal margin by 25°C. The 1N5196 operates to 175°C maximum, matching the BAY73TR. Applications operating near thermal limits require the 1N5196 or BAY73TR inventory.

Q: What is the impact of lower reverse leakage current in the 1N4448?

A: The 1N4448 exhibits 25 nA reverse leakage at 20 V, compared to the BAY73TR's 5 nA at 100 V. Higher reverse leakage increases standby power dissipation and may affect precision analog circuits. The 1N5196 exhibits 25 nA leakage at 225 V. Applications sensitive to leakage current should evaluate the specific operating voltage and thermal environment.

Q: Can the BAY73TR be used in new designs, or must substitutes be selected?

A: The BAY73TR is classified as obsolete. New designs should specify the 1N5196 for long-term availability and active product status. Existing designs using BAY73TR may continue with available inventory; however, transition planning to the 1N5196 is recommended for production continuity.

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