FDH444TR Equivalent & Substitute Parts

Part Overview

The FDH444TR is a general-purpose rectifier diode manufactured by onsemi, rated for 125 V DC reverse voltage and 200 mA average rectified current. The device is packaged in a DO-35 axial through-hole configuration and is classified as a small signal diode with reverse recovery time of 60 ns. This part is currently active in production status with ROHS3 compliance and REACH unaffected designation.

Equivalent and substitute parts are identified based on matching or exceeding the electrical performance parameters while maintaining compatible mechanical packaging and thermal characteristics. Substitutes must satisfy the same voltage rating, current capacity, and mounting requirements to ensure direct functional replacement in circuit applications.

Key Parameters

Parameter	FDH444TR	Unit
Voltage - DC Reverse (Vr) (Max)	125	V
Current - Average Rectified (Io)	200	mA
Voltage - Forward (Vf) (Max) @ If	1.2 @ 300 mA	V
Reverse Recovery Time (trr)	60	ns
Current - Reverse Leakage @ Vr	50 nA @ 100 V	nA
Capacitance @ Vr, F	2.5 @ 0V, 1MHz	pF
Operating Temperature - Junction (Max)	175	°C
Package / Case	DO-204AH, DO-35, Axial	—
Mounting Type	Through Hole	—
Technology	Standard	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the FDH444TR are identified from the BAS45A series manufactured by Nexperia USA Inc. The substitution logic is based on the following electrical and mechanical compatibility criteria:

Voltage Rating Compatibility: All substitute parts maintain the same 125 V DC reverse voltage maximum rating as the primary part, ensuring equivalent reverse bias protection.

Current Capacity: Substitute parts in the BAS45A series are rated for 250 mA average rectified current, which exceeds the 200 mA requirement of the FDH444TR. This higher current rating provides margin for circuit operation.

Package Compatibility: Substitute parts use the DO-34 axial through-hole package (DO-204AG), which is mechanically compatible with DO-35 applications in standard PCB layouts. Both packages are axial lead configurations suitable for through-hole mounting.

Thermal Rating: All substitute parts maintain the same 175°C maximum junction temperature operating range.

Compliance Status: All substitute parts carry ROHS3 compliance and REACH unaffected designation, matching the regulatory status of the primary part.

Speed Classification: Substitute parts are classified as standard recovery diodes with reverse recovery time of 1.5 µs, compared to the 60 ns small signal classification of the FDH444TR. This represents a functional difference in switching speed characteristics.

Parameter Comparison

Parameter	FDH444TR (onsemi)	BAS45A,113 (Nexperia)	BAS45A,133 (Nexperia)	BAS45A,143 (Nexperia)	Unit
Voltage - DC Reverse (Vr) (Max)	125	125	125	125	V
Current - Average Rectified (Io)	200	250	250	250	mA
Voltage - Forward (Vf) (Max) @ If	1.2 @ 300 mA	1 @ 100 mA	1 @ 100 mA	1 @ 100 mA	V
Reverse Recovery Time (trr)	60	1.5	1.5	1.5	ns / µs
Current - Reverse Leakage @ Vr	50 nA @ 100 V	1 nA @ 125 V	1 nA @ 125 V	1 nA @ 125 V	nA
Capacitance @ Vr, F	2.5 @ 0V, 1MHz	4 @ 0V, 1MHz	4 @ 0V, 1MHz	4 @ 0V, 1MHz	pF
Operating Temperature - Junction (Max)	175	175	175	175	°C
Package / Case	DO-204AH, DO-35	DO-204AG, DO-34	DO-204AG, DO-34	DO-204AG, DO-34	—
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	—

Engineering Selection Recommendations

Primary Part Status: The FDH444TR maintains active production status with full ROHS3 compliance and REACH unaffected regulatory standing. This part is suitable for new designs and ongoing production applications.

Substitute Part Status: All three BAS45A variants (BAS45A,113, BAS45A,133, and BAS45A,143) are active production parts from Nexperia USA Inc. with identical ROHS3 compliance and REACH unaffected designation. These parts are qualified alternatives for applications requiring equivalent or higher current capacity.

Compliance Equivalence: Both the primary part and all substitute parts meet the same regulatory requirements for hazardous substance restrictions and environmental compliance. No compliance barriers exist for substitution.

Inventory Availability: The FDH444TR has 10,708 pieces in stock. Substitute parts show higher inventory levels: BAS45A,113 (18,738 pcs), BAS45A,133 (10,460 pcs), and BAS45A,143 (4,178 pcs). Selection among substitutes may be influenced by supply chain requirements.

Electrical Performance Differences: Substitute parts provide higher current capacity (250 mA versus 200 mA) and lower reverse leakage current (1 nA versus 50 nA). However, substitute parts exhibit slower reverse recovery time (1.5 µs versus 60 ns), which affects switching speed performance in high-frequency applications.

Frequently Asked Questions (FAQ)

Q: Can BAS45A series diodes directly replace the FDH444TR in all applications?

A: BAS45A series diodes are electrically compatible for voltage and current ratings. However, the reverse recovery time differs significantly (1.5 µs versus 60 ns). Applications requiring fast switching or operating at high frequencies may experience performance changes. Circuit validation is necessary when switching speed is a critical design parameter.

Q: What is the difference between DO-35 and DO-34 packages?

A: Both DO-35 (DO-204AH) and DO-34 (DO-204AG) are axial lead through-hole packages with similar physical dimensions and mounting compatibility. The primary difference is in the lead diameter and case length specifications. Both packages are suitable for standard PCB through-hole mounting applications.

Q: Are all three BAS45A variants electrically identical?

A: BAS45A,113, BAS45A,133, and BAS45A,143 share identical electrical specifications. The numeric suffixes indicate different packaging or tape reel configurations from Nexperia. All three variants are functionally equivalent for circuit applications.

Q: What does the higher reverse leakage current in the FDH444TR indicate?

A: The FDH444TR exhibits 50 nA reverse leakage at 100 V compared to 1 nA in BAS45A variants. This represents a tenfold difference in leakage current. For applications sensitive to leakage current, such as precision analog circuits or high-impedance applications, the lower leakage of BAS45A parts may provide improved performance.

Q: Is the higher capacitance of BAS45A parts a concern?

A: BAS45A parts have 4 pF capacitance compared to 2.5 pF in the FDH444TR. This 1.5 pF difference is negligible in most general-purpose rectifier applications. High-frequency or RF applications may require evaluation of this parameter.

Q: What is the significance of the "Small Signal" versus "Standard Recovery" classification?

A: The FDH444TR is classified as a small signal diode with 60 ns reverse recovery time, suitable for fast switching applications. BAS45A parts are standard recovery diodes with 1.5 µs recovery time, designed for general-purpose rectification. Selection depends on the required switching speed of the application.

Q: Are all parts suitable for the same operating temperature range?

A: All parts maintain a maximum junction temperature of 175°C. They are suitable for identical thermal operating ranges in circuit applications.

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