BAY72 Equivalent & Substitute Parts

Part Overview

The BAY72 is a general-purpose rectifier diode manufactured by onsemi, rated for 125 V DC reverse voltage and 200 mA average rectified current in a DO-35 through-hole package. This part is classified as obsolete, making equivalent and substitute components necessary for ongoing design support and procurement continuity. The BAY72 operates with small signal speed characteristics and a maximum junction temperature of 175°C, suitable for standard rectification applications in legacy and new designs requiring compatible electrical performance.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	125	V
Current - Average Rectified (Io)	200	mA
Voltage - Forward (Vf) (Max) @ If	1 V @ 100 mA	V
Speed	Small Signal ≤ 200mA (Io), Any Speed	—
Reverse Recovery Time (trr)	50	ns
Current - Reverse Leakage @ Vr	100 nA @ 100 V	nA
Mounting Type	Through Hole	—
Package / Case	DO-204AH, DO-35, Axial	—
Operating Temperature - Junction (Max)	175	°C

Substitute Part Grouping Explanation

Substitute parts for the BAY72 are grouped based on electrical parameter compatibility within the following criteria:

Parametric Equivalents — Parts with identical or superior voltage rating (125 V minimum), matching current rating (200 mA), compatible forward voltage characteristics, and equivalent or improved reverse leakage performance. These parts maintain the same functional envelope and are direct replacements.

Similar Parts with Higher Voltage Rating — Parts rated for 150 V or higher reverse voltage with 200 mA current rating. These provide enhanced voltage margin and are electrically compatible for applications where the BAY72 operates below its maximum rating.

Similar Parts with Higher Current Rating — Parts rated for 250 mA or higher at 125 V reverse voltage. These provide current margin and are suitable for applications where the BAY72 operates below its maximum current rating.

Package Considerations — All substitute parts maintain through-hole axial mounting in DO-35 or DO-34 packages, ensuring mechanical compatibility with existing PCB layouts and assembly processes.

Key Substitution Parameters:

Voltage - DC Reverse (Vr) (Max): ≥ 125 V
Current - Average Rectified (Io): ≥ 200 mA
Mounting Type: Through Hole
Package / Case: DO-35 or DO-34 compatible
Operating Temperature - Junction (Max): ≥ 175°C

Parameter Comparison

Part Number	Manufacturer	Vr (Max) [V]	Io [mA]	Vf (Max) @ If [V]	trr [ns/µs]	Ir @ Vr [nA/µA]	Package	Product Status
BAY72	onsemi	125	200	1 @ 100 mA	50 ns	100 nA @ 100 V	DO-35	Obsolete
FDH300A_NL	Fairchild Semiconductor	125	200	1 @ 200 mA	—	1 nA @ 125 V	DO-35	Active
FDH300A	onsemi	125	200	1 @ 200 mA	—	1 nA @ 125 V	DO-35	Active
FDH3595	onsemi	125	200	1 @ 200 mA	—	1 nA @ 125 V	DO-35	Active
1N3595TR	onsemi	150	200	1 @ 200 mA	3 µs	1 nA @ 125 V	DO-35	Active
1N484B	Microchip Technology	125	200	1 @ 100 mA	—	25 nA @ 125 V	DO-35	Active
1N458	Microchip Technology	150	150	1 @ 100 mA	—	1 µA @ 150 V	DO-35	Active
BAV19-TR	Vishay General Semiconductor - Diodes Division	100	250	1 @ 100 mA	50 ns	100 nA @ 100 V	DO-35	Active
BAS45A,113	Nexperia USA Inc.	125	250	1 @ 100 mA	1.5 µs	1 nA @ 125 V	DO-34	Active
BAS45A,133	Nexperia USA Inc.	125	250	1 @ 100 mA	1.5 µs	1 nA @ 125 V	DO-34	Active
BAS45A,143	Nexperia USA Inc.	125	250	1 @ 100 mA	1.5 µs	1 nA @ 125 V	DO-34	Active

Engineering Selection Recommendations

Parametric Equivalents (Direct Replacements)

FDH300A, FDH300A_NL, and FDH3595 are parametric equivalents to the BAY72, offering identical voltage and current ratings with active product status. FDH300A and FDH3595 are manufactured by onsemi and carry RoHS3 compliance. FDH300A_NL is manufactured by Fairchild Semiconductor with active status. These parts are suitable for direct substitution in applications where the BAY72 is specified.

Higher Voltage Rating Alternatives

1N3595TR (onsemi) provides 150 V reverse voltage rating with 200 mA current capacity and active product status with RoHS3 compliance. This part is suitable for applications requiring enhanced voltage margin while maintaining the same current handling capability.

Higher Current Rating Alternatives

BAS45A variants (BAS45A,113, BAS45A,133, BAS45A,143) from Nexperia USA Inc. provide 250 mA current rating at 125 V reverse voltage with active product status and RoHS3 compliance. These parts are suitable for applications requiring increased current capacity. Note that BAS45A variants use DO-34 packaging instead of DO-35, requiring PCB layout verification for mechanical compatibility.

Compliance and Regulatory Status

Parts with active product status and RoHS3 compliance are preferred for new designs and long-term procurement continuity. The BAY72 is obsolete; therefore, migration to active alternatives is necessary for sustained component availability. All recommended substitutes maintain REACH Unaffected status and EAR99 export classification consistent with the original part.

Microchip Technology Alternatives

1N484B (Microchip Technology) provides 125 V / 200 mA ratings with active status but carries RoHS non-compliant designation. This part is suitable for legacy applications where RoHS compliance is not required. 1N458 (Microchip Technology) provides 150 V rating but with reduced current capacity (150 mA), limiting its application scope.

Vishay General Semiconductor Alternative

BAV19-TR provides 100 V reverse voltage with 250 mA current capacity, automotive qualification (AEC-Q101), and active status with RoHS3 compliance. This part is suitable for applications operating below 100 V where automotive-grade reliability is required. The 100 V rating is lower than the BAY72 specification and requires application voltage verification.

Frequently Asked Questions (FAQ)

Q: Can FDH300A directly replace BAY72 in existing designs?

A: Yes. FDH300A provides identical voltage (125 V) and current (200 mA) ratings with the same DO-35 through-hole package. Both parts maintain 175°C maximum junction temperature. FDH300A carries active product status and RoHS3 compliance, making it suitable for direct substitution.

Q: What is the difference between FDH300A and FDH300A_NL?

A: Both parts provide identical electrical specifications (125 V, 200 mA, DO-35 package). FDH300A is manufactured by onsemi with RoHS3 compliance. FDH300A_NL is manufactured by Fairchild Semiconductor with non-applicable RoHS status. Selection depends on manufacturer preference and supply chain requirements.

Q: Can 1N3595TR be used instead of BAY72?

A: Yes, with voltage margin consideration. 1N3595TR provides 150 V reverse voltage (25 V higher than BAY72) and 200 mA current rating with identical DO-35 packaging. This part is suitable for applications where the BAY72 operates below its 125 V maximum rating. 1N3595TR carries active product status and RoHS3 compliance.

Q: Why do BAS45A variants have different part numbers (113, 133, 143)?

A: BAS45A,113, BAS45A,133, and BAS45A,143 are packaging variants of the same base part (BAS45A) with identical electrical specifications. All three provide 125 V / 250 mA ratings in DO-34 packaging. Selection depends on packaging and tape configuration requirements. Verify PCB layout compatibility with DO-34 package dimensions before substitution.

Q: Is BAV19-TR suitable for replacing BAY72?

A: BAV19-TR is not a direct replacement. It provides 100 V reverse voltage (25 V lower than BAY72) with 250 mA current capacity. This part is suitable only for applications where the operating voltage is confirmed to be below 100 V. BAV19-TR carries automotive qualification (AEC-Q101) and is suitable for automotive applications requiring this certification.

Q: What is the impact of package differences between DO-35 and DO-34?

A: DO-35 and DO-34 are both axial through-hole packages with different physical dimensions. DO-34 is slightly smaller than DO-35. Substitution requires PCB layout verification to confirm that component lead spacing and hole positioning accommodate the alternative package. Mechanical compatibility must be confirmed before design implementation.

Q: Which substitute part offers the best compliance profile for new designs?

A: FDH300A, FDH3595, 1N3595TR, and BAS45A variants all carry active product status and RoHS3 compliance. FDH300A and FDH3595 (onsemi) provide parametric equivalence with identical voltage and current ratings. These parts are recommended for new designs requiring sustained component availability and regulatory compliance.

Q: Can 1N484B be used in applications requiring RoHS compliance?

A: No. 1N484B carries RoHS non-compliant designation. This part is suitable only for legacy applications where RoHS compliance is not required. For new designs or applications requiring RoHS compliance, select from FDH300A, FDH3595, 1N3595TR, or BAS45A variants.

Q: What is the significance of reverse recovery time (trr) differences?

A: Reverse recovery time affects switching speed and switching losses. BAY72 specifies 50 ns (fast recovery). FDH300A and FDH3595 do not specify trr. 1N3595TR specifies 3 µs (slower recovery). BAV19-TR specifies 50 ns (matching BAY72). BAS45A variants specify 1.5 µs. For applications sensitive to switching speed, BAY72 and BAV19-TR are preferred. For general rectification, differences are not critical.

Q: Are there inventory considerations for substitute part selection?

A: Yes. Inventory levels vary significantly. FDH300A_NL (15,062 pcs), 1N3595TR (50,821 pcs), and BAV19-TR (38,866 pcs) have substantial inventory. FDH3595 (719 pcs) and 1N458 (737 pcs) have limited inventory. For long-term procurement, parts with higher inventory levels provide better supply continuity.

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