FR304-T Equivalent & Substitute Parts

Part Overview

The FR304-T is a general-purpose rectifier diode manufactured by Diodes Incorporated, rated for 400 V DC reverse voltage and 3 A average rectified current in a through-hole DO-201AD axial package. This component is classified as obsolete, which necessitates identification of equivalent and substitute parts for ongoing design support and procurement continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives within acceptable parameter tolerances for the 400 V / 3 A rectifier diode category.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	400	V
Current - Average Rectified (Io)	3	A
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 3 A	V
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	—
Reverse Recovery Time (trr)	150	ns
Current - Reverse Leakage @ Vr	10	µA @ 400 V
Mounting Type	Through Hole	—
Package / Case	DO-201AD, Axial	—
Operating Temperature - Junction	-65 to 175	°C
Technology	Standard	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the FR304-T is determined by the following critical parameters:

Mandatory Matching Criteria:

Voltage - DC Reverse (Vr) (Max): 400 V
Current - Average Rectified (Io): 3 A
Mounting Type: Through Hole
Package / Case: DO-201AD or equivalent axial package

Acceptable Variation Ranges:

Voltage - Forward (Vf) (Max) @ If: 0.95 V to 1.5 V @ 3 A
Reverse Recovery Time (trr): 30 ns to 150 ns (fast recovery preferred)
Current - Reverse Leakage @ Vr: 1 µA to 20 µA @ 400 V
Operating Temperature - Junction: Minimum -40°C, Maximum 125°C or higher

Substitute parts are grouped into two categories: direct equivalents (matching all parameters within tight tolerances) and functional alternatives (meeting core electrical ratings with acceptable deviations in secondary characteristics such as recovery time or leakage current).

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vr (Max) [V]	Io [A]	Vf (Max) @ If [V]	Speed	trr [ns]	Ir @ Vr [µA]	Package	Tj (°C)	Product Status
FR304-T	Diodes Incorporated	400	3	1.3 @ 3A	Fast Recovery ≤ 500ns	150	10 @ 400V	DO-201AD	-65 to 175	Obsolete
1N5404-G	Comchip Technology	400	3	0.95 @ 3A	Standard Recovery >500ns	—	5 @ 400V	DO-201AD	-65 to 125	Active
1N5404G	onsemi	400	3	1.0 @ 3A	Standard Recovery >500ns	—	10 @ 400V	DO-201AA / DO-27	-65 to 150	Not For New Designs
1N5404RLG	onsemi	400	3	1.0 @ 3A	Standard Recovery >500ns	—	10 @ 400V	DO-201AA / DO-27	-65 to 150	Not For New Designs
1N5418	Microchip Technology	400	3	1.5 @ 9A	Fast Recovery ≤ 500ns	150	1 @ 400V	SQ-MELF, B	-65 to 175	Active
1N6543	Microchip Technology	—	—	—	—	—	—	A-PKG	—	Active
31GF4-E3/73	Vishay General Semiconductor - Diodes Division	400	3	1.25 @ 3A	Fast Recovery ≤ 500ns	30	20 @ 400V	DO-201AD	-40 to 150	Active
31GF4-M3/73	Vishay General Semiconductor - Diodes Division	400	3	1.25 @ 3A	Fast Recovery ≤ 500ns	30	20 @ 400V	DO-201AD	-40 to 150	Active
BY252P-E3/54	Vishay General Semiconductor - Diodes Division	400	3	1.1 @ 3A	Standard Recovery >500ns	3000	5 @ 400V	DO-201AD	-55 to 150	Active
EGP30G	onsemi	400	3	1.25 @ 3A	Fast Recovery ≤ 500ns	50	5 @ 400V	DO-201AD	-65 to 150	Not For New Designs
FR304GP-AP	Micro Commercial Co	400	3	1.3 @ 3A	Fast Recovery ≤ 500ns	150	5 @ 400V	DO-201AD	-55 to 150	Active

Engineering Selection Recommendations

Direct Equivalents (Preferred for Replacement):

The FR304GP-AP (Micro Commercial Co) provides the closest functional match to the FR304-T. Both parts share identical voltage and current ratings, fast recovery characteristics with 150 ns reverse recovery time, and DO-201AD package configuration. The FR304GP-AP is currently in active production status, ensuring long-term availability and supply chain stability.

Active Production Alternatives:

For applications where the FR304GP-AP is unavailable, the following parts are suitable substitutes:

31GF4-E3/73 and 31GF4-M3/73 (Vishay): These parts meet all core electrical requirements with improved reverse recovery time (30 ns) and are ROHS3 compliant. Operating temperature range is -40°C to 150°C, which is acceptable for most industrial applications.
1N5404-G (Comchip Technology): Provides 400 V / 3 A ratings with lower forward voltage (0.95 V @ 3 A) and reduced reverse leakage (5 µA). Uses standard recovery characteristics (>500 ns), suitable for non-critical switching applications.
BY252P-E3/54 (Vishay): Meets voltage and current specifications with standard recovery characteristics and low forward voltage (1.1 V @ 3 A). Includes capacitance specification (40 pF @ 4 V, 1 MHz) for applications requiring predictable parasitic behavior.

Not Recommended for New Designs:

Parts marked "Not For New Designs" (1N5404G, 1N5404RLG, EGP30G) are suitable only for legacy system maintenance and repair. These parts remain available but are not recommended for new circuit development.

Package Consideration:

The 1N5418 (Microchip Technology) is a surface-mount alternative in SQ-MELF package. This part is suitable only for applications where surface-mount technology is specified. It is not a direct replacement for through-hole applications.

Compliance Status:

All recommended substitute parts are ROHS3 compliant. The 1N5418 is RoHS non-compliant and should be avoided in applications requiring RoHS certification.

Frequently Asked Questions (FAQ)

Q: Can the FR304-T be directly replaced with the 1N5404-G?

A: Yes, the 1N5404-G is a functional substitute. Both parts are rated for 400 V / 3 A in DO-201AD packages. The 1N5404-G has lower forward voltage (0.95 V vs. 1.3 V) and uses standard recovery characteristics instead of fast recovery. For applications not sensitive to switching speed, this substitution is acceptable.

Q: What is the difference between fast recovery and standard recovery diodes?

A: Fast recovery diodes (trr ≤ 500 ns) are designed for high-frequency switching applications and exhibit lower reverse recovery time. Standard recovery diodes (trr > 500 ns) are suitable for lower-frequency rectification and general-purpose applications. The FR304-T specifies fast recovery with 150 ns trr. Substitutes with standard recovery (such as 1N5404-G or BY252P-E3/54) are acceptable in applications where switching frequency does not exceed the diode's recovery capability.

Q: Are the 31GF4-E3/73 and 31GF4-M3/73 interchangeable?

A: Yes, both parts are electrically identical. The difference lies in packaging designation. Both are suitable replacements for the FR304-T and offer improved reverse recovery time (30 ns) compared to the original part.

Q: Why is the operating temperature range different across substitute parts?

A: Operating temperature range is determined by the semiconductor material and package design. The FR304-T specifies -65°C to 175°C, while some substitutes (such as 1N5404-G) specify -65°C to 125°C. For applications operating within the lower temperature range, these parts are fully compatible. Applications requiring operation above 125°C must use parts with extended temperature ratings.

Q: Can the 1N5418 replace the FR304-T in a through-hole circuit?

A: No. The 1N5418 is a surface-mount device in SQ-MELF package, while the FR304-T is a through-hole axial component. Physical mounting incompatibility prevents direct substitution. The 1N5418 is suitable only for new designs using surface-mount technology.

Q: What does "Not For New Designs" mean?

A: Parts designated "Not For New Designs" are in mature or declining production phases. While they remain available for legacy system support and repair, manufacturers do not recommend their use in new circuit development. For new designs, select parts with "Active" product status to ensure long-term availability and supply chain continuity.

Q: How do I verify that a substitute part is compatible with my application?

A: Verify compatibility by confirming that the substitute part meets or exceeds the following minimum requirements: (1) Voltage - DC Reverse rating ≥ 400 V, (2) Current - Average Rectified rating ≥ 3 A, (3) Operating temperature range encompasses your application's thermal requirements, (4) Package type matches your circuit board design (through-hole DO-201AD for the FR304-T), and (5) RoHS compliance status matches your regulatory requirements.

Q: What is the significance of reverse leakage current variation?

A: Reverse leakage current (Ir) represents the small current flowing through the diode in reverse bias. The FR304-T specifies 10 µA @ 400 V. Substitutes range from 1 µA to 20 µA. Lower leakage current improves efficiency in high-impedance circuits and reduces power dissipation. Higher leakage current is acceptable in most general-purpose rectification applications. Select parts with lower leakage (1–5 µA) for precision analog circuits or battery-powered applications.

Q: Are all substitute parts ROHS3 compliant?

A: No. The 1N5418 is RoHS non-compliant. All other recommended substitutes are ROHS3 compliant. Verify RoHS compliance status before selecting a substitute for applications subject to RoHS regulations.

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