FDH300A_T50R Equivalent & Substitute Parts

Part Overview

The FDH300A_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 components necessary for ongoing design support and procurement continuity. The FDH300A_T50R serves applications requiring small-signal rectification with standard recovery characteristics and operates at a maximum junction temperature of 175°C.

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 @ 200 mA	V
Speed Classification	Small Signal ≤ 200mA (Io), Any Speed	—
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
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the FDH300A_T50R is determined by matching the following critical electrical and mechanical parameters:

Primary Matching Criteria:

Voltage - DC Reverse (Vr) (Max): 125 V minimum
Current - Average Rectified (Io): 200 mA minimum
Mounting Type: Through Hole
Package compatibility: DO-35 or equivalent axial configuration

Secondary Compatibility Factors:

Forward voltage (Vf) characteristics at rated current
Reverse leakage current performance
Operating temperature range
Speed classification (Small Signal, Any Speed)

Substitute parts are grouped into two categories: Parametric Equivalents (identical electrical ratings and active product status) and Similar Parts (matching core electrical parameters with variations in packaging, speed characteristics, or manufacturer).

Parameter Comparison

Part Number	Manufacturer	Vr (Max) [V]	Io [mA]	Vf (Max) [V]	Package	Product Status	Temp Range [°C]
FDH300A_T50R	onsemi	125	200	1 @ 200 mA	DO-35	Obsolete	—/175
FDH300ATR	onsemi	125	200	1 @ 200 mA	DO-35	Active	—/175
FDH300TR	onsemi	125	200	1 @ 200 mA	DO-35	Active	—/175
BAY72TR	Fairchild Semiconductor	125	200	1 @ 100 mA	DO-35	Active	—/175
1N3595	Microchip Technology	125	200	1 @ 200 mA	Axial	Active	-65/150
BAV20,113	Nexperia USA Inc.	150	250	1.25 @ 200 mA	ALF2	Active	—/175
BAV20,133	NXP USA Inc.	150	250	1.25 @ 200 mA	ALF2	Active	—/175
BAV20,143	Nexperia USA Inc.	150	250	1.25 @ 200 mA	ALF2	Active	—/175
1N4448	Microchip Technology	75	200	1 @ 100 mA	DO-35	Discontinued at DiGi Electronics	-65/150

Engineering Selection Recommendations

Recommended Primary Substitutes (Parametric Equivalents):

FDH300ATR and FDH300TR are direct parametric equivalents to the FDH300A_T50R. Both are manufactured by onsemi with identical electrical specifications (125 V, 200 mA, 1 V forward voltage at 200 mA) and the same DO-35 package. Both parts carry Active product status and are RoHS3 compliant, providing long-term availability and regulatory compliance. These parts are the preferred substitutes for direct replacement in existing designs.

Alternative Substitutes (Electrical Equivalents with Package Variations):

BAY72TR (Fairchild Semiconductor) provides identical voltage and current ratings with Active product status. The forward voltage specification differs slightly (1 V @ 100 mA versus 1 V @ 200 mA), but remains within acceptable operating parameters for general-purpose rectification applications.

1N3595 (Microchip Technology) matches the core electrical specifications (125 V, 200 mA, 1 V @ 200 mA) and is Active. This part uses an Axial package instead of DO-35, requiring mechanical redesign for board layout compatibility.

Higher-Rated Alternatives (Derating Consideration):

BAV20,113, BAV20,133, and BAV20,143 (Nexperia/NXP) provide elevated voltage (150 V) and current (250 mA) ratings with Active status. These parts are suitable for applications where design margin or future specification changes warrant higher ratings. The ALF2 package differs from DO-35, necessitating mechanical evaluation.

Not Recommended:

1N4448 (Microchip Technology) has a reduced reverse voltage rating of 75 V, which is insufficient for the 125 V specification of the FDH300A_T50R. This part is also discontinued at DiGi Electronics and carries RoHS non-compliant status.

Frequently Asked Questions (FAQ)

Q: Can FDH300ATR or FDH300TR be used as direct replacements for FDH300A_T50R?

A: Yes. FDH300ATR and FDH300TR are parametric equivalents with identical electrical ratings (125 V, 200 mA, 1 V forward voltage) and the same DO-35 package. Both are Active products with current manufacturing support. The primary difference is packaging format (Cut Tape versus the original format), which does not affect electrical performance or board-level compatibility.

Q: What is the difference between DO-35 and Axial packages?

A: Both are through-hole packages for axial-lead diodes. DO-35 is a standardized package designation (DO-204AH), while Axial refers to the lead configuration. Mechanically, they are compatible for most applications, but board layout and component placement may require adjustment. The 1N3595 uses an Axial package and is electrically equivalent to the FDH300A_T50R.

Q: Why are BAV20 series parts listed as substitutes if they have higher voltage and current ratings?

A: BAV20,113, BAV20,133, and BAV20,143 exceed the minimum electrical requirements of the FDH300A_T50R (150 V versus 125 V, 250 mA versus 200 mA). These parts are suitable substitutes when design margins are desired or when future specification changes may require higher ratings. However, the ALF2 package differs from DO-35, requiring mechanical evaluation before implementation.

Q: Is 1N4448 a suitable substitute?

A: No. The 1N4448 has a maximum reverse voltage rating of 75 V, which is insufficient for the 125 V specification of the FDH300A_T50R. Additionally, 1N4448 is discontinued at DiGi Electronics and does not meet current RoHS compliance requirements.

Q: What compliance certifications should I verify when selecting a substitute?

A: All recommended substitutes carry REACH Unaffected status and EAR99 export classification, matching the FDH300A_T50R. FDH300ATR and FDH300TR are RoHS3 compliant. BAY72TR compliance status should be verified with the manufacturer. Ensure selected parts meet your application's regulatory and environmental requirements.

Q: Can I use a substitute with a lower reverse voltage rating?

A: No. The reverse voltage rating must equal or exceed the FDH300A_T50R specification of 125 V. Using a part with a lower rating (such as 1N4448 at 75 V) creates risk of diode failure under reverse bias conditions and is not acceptable for engineering applications.

Q: What is the significance of the "Small Signal ≤ 200mA (Io), Any Speed" classification?

A: This classification indicates the diode is designed for small-signal rectification applications with currents up to 200 mA and has no specific speed requirement (standard or fast recovery). All recommended substitutes share this classification, ensuring functional compatibility in the intended application domain.

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