FDH300_T50R Equivalent & Substitute Parts

Part Overview

The FDH300_T50R 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 parts necessary for ongoing design support and procurement continuity. The FDH300_T50R serves applications requiring small-signal rectification with moderate voltage and current ratings in compact axial packaging.

Key Parameters

Parameter	Value
Voltage - DC Reverse (Vr) (Max)	125 V
Current - Average Rectified (Io)	200 mA
Voltage - Forward (Vf) (Max) @ If	1 V @ 200 mA
Current - Reverse Leakage @ Vr	1 nA @ 125 V
Capacitance @ Vr, F	6 pF @ 0V, 1MHz
Mounting Type	Through Hole
Package / Case	DO-204AH, DO-35, Axial
Operating Temperature - Junction (Max)	175°C
Speed Classification	Small Signal ≤ 200mA (Io), Any Speed

Substitute Part Grouping Explanation

Substitution for the FDH300_T50R is determined by the following critical parameters: reverse voltage rating (Vr), average rectified current (Io), forward voltage drop (Vf), reverse leakage current, package type, and mounting configuration. All substitute parts must maintain through-hole axial mounting in DO-35 or equivalent packaging to ensure mechanical and electrical compatibility.

Substitute parts are grouped into two categories:

Parametric Equivalents maintain identical or superior electrical specifications across all critical parameters, including 125 V reverse voltage rating and 200 mA current capacity. These parts are direct functional replacements with no derating required.

Similar Parts offer comparable functionality with variations in one or more parameters. These parts may have higher voltage ratings, increased current capacity, or different speed characteristics, but remain compatible within the application's electrical constraints.

Parameter Comparison

Part Number	Manufacturer	Vr (Max)	Io	Vf (Max) @ If	Reverse Leakage @ Vr	Package	Product Status
FDH300_T50R	onsemi	125 V	200 mA	1 V @ 200 mA	1 nA @ 125 V	DO-35	Obsolete
FDH300TR	onsemi	125 V	200 mA	1 V @ 200 mA	1 nA @ 125 V	DO-35	Active
FDH300ATR	onsemi	125 V	200 mA	1 V @ 200 mA	1 nA @ 125 V	DO-35	Active
BAY72TR	Fairchild Semiconductor	125 V	200 mA	1 V @ 100 mA	100 nA @ 100 V	DO-35	Active
BAV20,113	Nexperia USA Inc.	150 V	250 mA	1.25 V @ 200 mA	100 nA @ 150 V	ALF2	Active
BAV20,133	NXP USA Inc.	150 V	250 mA	1.25 V @ 200 mA	100 nA @ 150 V	ALF2	Active
BAV20,143	Nexperia USA Inc.	150 V	250 mA	1.25 V @ 200 mA	100 nA @ 150 V	ALF2	Active
1N458	Microchip Technology	150 V	150 mA	1 V @ 100 mA	1 µA @ 150 V	DO-35	Active
1N4448	Microchip Technology	75 V	200 mA	1 V @ 100 mA	25 nA @ 20 V	DO-35	Discontinued at DiGi Electronics

Engineering Selection Recommendations

Primary Recommendation: FDH300TR or FDH300ATR

Both FDH300TR and FDH300ATR are active onsemi products that provide complete parametric equivalence to the obsolete FDH300_T50R. These parts maintain identical electrical specifications: 125 V reverse voltage, 200 mA current rating, 1 V forward voltage drop at 200 mA, and 1 nA reverse leakage at 125 V. Both are RoHS3 compliant and carry REACH Unaffected status. FDH300TR is available in higher inventory (35,400 units) compared to FDH300ATR (4,200 units), making it the preferred choice for volume applications. Both parts are supplied in cut tape packaging and are suitable for direct replacement without circuit modification.

Secondary Recommendation: BAY72TR

BAY72TR from Fairchild Semiconductor is an active parametric equivalent offering identical 125 V and 200 mA ratings in DO-35 packaging. This part exhibits higher reverse leakage current (100 nA @ 100 V versus 1 nA @ 125 V) and longer reverse recovery time (50 ns), which may affect performance in high-frequency or low-leakage applications. BAY72TR is available in bulk packaging with substantial inventory (80,843 units) and is suitable for applications where the increased leakage and recovery time specifications are acceptable.

Alternative Consideration: BAV20 Series (BAV20,113 / BAV20,133 / BAV20,143)

The BAV20 series from Nexperia/NXP offers superior electrical ratings with 150 V reverse voltage and 250 mA current capacity, providing design margin above the FDH300_T50R specifications. These parts feature fast recovery characteristics (50 ns) and are RoHS3 compliant. However, BAV20 parts use ALF2 packaging rather than DO-35, requiring PCB layout modification. Forward voltage is higher at 1.25 V @ 200 mA. These parts are suitable for applications requiring enhanced voltage and current margins with tolerance for package change.

Limited Compatibility: 1N458

The 1N458 from Microchip Technology offers 150 V reverse voltage in DO-35 packaging but is rated for only 150 mA average rectified current, below the FDH300_T50R specification of 200 mA. This part is suitable only for applications where the actual circuit current requirement does not exceed 150 mA. Reverse leakage is significantly higher at 1 µA @ 150 V.

Not Recommended: 1N4448

The 1N4448 from Microchip Technology has a reduced reverse voltage rating of 75 V, which is insufficient for the FDH300_T50R's 125 V specification. This part is not suitable for direct substitution and is discontinued at DiGi Electronics.

Frequently Asked Questions (FAQ)

Q: Can FDH300TR be used as a direct replacement for FDH300_T50R without circuit modification?

A: Yes. FDH300TR is a parametric equivalent with identical electrical specifications: 125 V reverse voltage, 200 mA current rating, 1 V forward voltage drop at 200 mA, and 1 nA reverse leakage at 125 V. Both parts use DO-35 through-hole axial packaging. No circuit modification is required.

Q: What is the difference between FDH300TR and FDH300ATR?

A: Both parts are parametric equivalents with identical electrical specifications. The primary difference is packaging format: FDH300TR is supplied in cut tape (CT) packaging with 35,400 units in stock, while FDH300ATR is also supplied in cut tape with 4,200 units in stock. Both are RoHS3 compliant and active products. FDH300TR is recommended for volume applications due to higher inventory availability.

Q: Why is BAY72TR not the primary recommendation despite being an active parametric equivalent?

A: While BAY72TR maintains the 125 V and 200 mA ratings, it exhibits higher reverse leakage current (100 nA @ 100 V versus 1 nA @ 125 V) and longer reverse recovery time (50 ns). For applications sensitive to leakage or operating at high frequencies, FDH300TR or FDH300ATR are superior choices. BAY72TR is suitable for general-purpose applications where these parameter differences are acceptable.

Q: Can BAV20 series parts replace FDH300_T50R?

A: BAV20 series parts (BAV20,113 / BAV20,133 / BAV20,143) offer superior electrical ratings with 150 V reverse voltage and 250 mA current capacity. However, they use ALF2 packaging instead of DO-35, requiring PCB layout modification. Forward voltage is higher at 1.25 V @ 200 mA. These parts are suitable only if the application can accommodate package change and higher forward voltage drop.

Q: Is 1N458 a suitable substitute?

A: 1N458 is not recommended as a primary substitute. Although it offers 150 V reverse voltage in DO-35 packaging, its 150 mA current rating is below the FDH300_T50R specification of 200 mA. This part is suitable only for applications where actual circuit current does not exceed 150 mA. Reverse leakage is also significantly higher at 1 µA @ 150 V.

Q: What compliance certifications should I verify for substitute parts?

A: All recommended substitute parts (FDH300TR, FDH300ATR, BAY72TR, and BAV20 series) carry REACH Unaffected status and are RoHS3 compliant. All parts are classified under ECCN EAR99 and HTSUS 8541.10.0070. Verify compliance documentation with your supplier for specific application requirements.

Q: Can I use 1N4448 as a substitute?

A: No. The 1N4448 has a maximum reverse voltage rating of 75 V, which is insufficient for the FDH300_T50R's 125 V specification. This part is not suitable for direct substitution. Additionally, 1N4448 is discontinued at DiGi Electronics.

Q: What is the operating temperature range for substitute parts?

A: FDH300TR, FDH300ATR, and BAY72TR all support a maximum junction temperature of 175°C, matching the FDH300_T50R specification. BAV20 series parts also support 175°C maximum junction temperature. The 1N458 supports a lower range of -65°C to 150°C, limiting its high-temperature application suitability.

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