HER304-TP Equivalent & Substitute Parts

Part Overview

The HER304-TP is a general-purpose rectifier diode manufactured by Micro Commercial Co, rated for 300 V DC reverse voltage and 3 A average rectified current in a DO-201AD axial through-hole package. This part is classified as obsolete, necessitating identification of active equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain electrical performance within the specified voltage and current ratings while accommodating packaging and availability constraints.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	300	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)	50	ns
Current - Reverse Leakage @ Vr	10	µA @ 300 V
Package / Case	DO-201AD, Axial	—
Mounting Type	Through Hole	—
Operating Temperature - Junction	-55 to 150	°C
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the HER304-TP are classified into two categories based on electrical and mechanical compatibility:

Direct Manufacturer Substitute (Packaging Variant): The HER304G-TP from Micro Commercial Co maintains identical electrical specifications and package type but differs in product status (active vs. obsolete) and packaging format (Tape & Reel vs. bulk). This part is a direct functional replacement with no performance trade-offs.

Parametric Equivalents (Cross-Manufacturer): The SF35G and SF35GH from Taiwan Semiconductor Corporation meet or exceed the core electrical requirements: 300 V reverse voltage rating, 3 A average rectified current, DO-201AD package, and through-hole mounting. These parts demonstrate improved performance in reverse recovery time (35 ns vs. 50 ns) and reduced reverse leakage current (5 µA vs. 10 µA). The SF35GH variant includes automotive-grade qualification (AEC-Q101), suitable for applications requiring enhanced reliability standards.

Substitution eligibility is determined by:

Voltage - DC Reverse (Vr) rating ≥ 300 V
Current - Average Rectified (Io) rating ≥ 3 A
Package / Case: DO-201AD, Axial
Mounting Type: Through Hole
Operating Temperature range: -55°C to 150°C minimum

Parameter Comparison

Parameter	HER304-TP	HER304G-TP	SF35G	SF35GH
Manufacturer	Micro Commercial Co	Micro Commercial Co	Taiwan Semiconductor Corporation	Taiwan Semiconductor Corporation
Product Status	Obsolete	Active	Active	Active
Voltage - DC Reverse (Vr) (Max)	300 V	300 V	300 V	300 V
Current - Average Rectified (Io)	3 A	3 A	3 A	3 A
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 3 A	950 mV @ 3 A	1.3 V @ 3 A	1.3 V @ 3 A
Reverse Recovery Time (trr)	50 ns	50 ns	35 ns	35 ns
Current - Reverse Leakage @ Vr	10 µA @ 300 V	10 µA @ 300 V	5 µA @ 300 V	5 µA @ 300 V
Capacitance @ Vr, F	80 pF @ 4V, 1MHz	80 pF @ 4V, 1MHz	60 pF @ 4V, 1MHz	60 pF @ 4V, 1MHz
Package / Case	DO-201AD, Axial	DO-201AD, Axial	DO-201AD, Axial	DO-201AD, Axial
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Operating Temperature - Junction	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Packaging Format	Bulk	Tape & Reel (TR)	Cut Tape (CT)	Cut Tape (CT)
Automotive Grade / Qualification	—	—	—	AEC-Q101

Engineering Selection Recommendations

HER304G-TP Selection Criteria: The HER304G-TP is the primary substitute for the obsolete HER304-TP. Both parts are manufactured by Micro Commercial Co and share identical electrical specifications and package geometry. The HER304G-TP maintains active product status, ensuring long-term availability and supply chain continuity. The forward voltage characteristic is improved (950 mV vs. 1.3 V @ 3 A), resulting in reduced power dissipation. Selection of HER304G-TP is appropriate for direct replacement in existing designs without circuit modification. Packaging format differs (Tape & Reel vs. bulk), requiring adjustment to procurement and assembly processes.

SF35G Selection Criteria: The SF35G from Taiwan Semiconductor Corporation is a parametric equivalent suitable for applications where cross-manufacturer sourcing is acceptable. This part meets all electrical requirements and improves upon the original HER304-TP in reverse recovery time (35 ns vs. 50 ns) and reverse leakage current (5 µA vs. 10 µA). The SF35G is supplied in Cut Tape format. Selection is appropriate for new designs or redesigns where performance enhancement is beneficial and supply diversification is desired.

SF35GH Selection Criteria: The SF35GH is identical to the SF35G with the addition of automotive-grade qualification (AEC-Q101). This variant is required for applications subject to automotive industry reliability and qualification standards. The SF35GH demonstrates the same electrical performance improvements as the SF35G. Selection is mandatory for automotive applications and optional for industrial applications where enhanced qualification provides additional assurance.

Product Status Consideration: The HER304-TP is classified as obsolete. The HER304G-TP, SF35G, and SF35GH are all active products, ensuring continued manufacturing and availability. For new designs, selection of an active product is required. For legacy system support, HER304G-TP provides the most direct transition path.

Frequently Asked Questions (FAQ)

Q: Can the HER304G-TP be used as a direct replacement for the HER304-TP?

A: Yes. The HER304G-TP is manufactured by the same company (Micro Commercial Co) and maintains identical electrical specifications, package type (DO-201AD), and mounting method (through-hole). The primary difference is packaging format (Tape & Reel vs. bulk) and product status (active vs. obsolete). No circuit modifications are required.

Q: What are the advantages of using SF35G or SF35GH over HER304G-TP?

A: The SF35G and SF35GH offer improved reverse recovery time (35 ns vs. 50 ns) and reduced reverse leakage current (5 µA vs. 10 µA). These characteristics result in faster switching performance and lower standby current. The SF35GH additionally includes AEC-Q101 automotive qualification. These improvements are beneficial in high-frequency switching applications and automotive environments but are not required for general-purpose rectification.

Q: Are all substitute parts available in the same package?

A: Yes. All substitute parts (HER304G-TP, SF35G, SF35GH) use the DO-201AD axial through-hole package, ensuring mechanical compatibility with existing PCB layouts and assembly equipment. Packaging format differs (Tape & Reel vs. Cut Tape), affecting procurement and handling but not physical installation.

Q: Which substitute should be selected for automotive applications?

A: The SF35GH is the appropriate selection for automotive applications due to AEC-Q101 qualification. This certification confirms compliance with automotive industry reliability and testing standards. The SF35GH maintains all electrical performance characteristics of the SF35G while providing the required qualification documentation.

Q: Is the forward voltage difference between HER304G-TP (950 mV) and HER304-TP (1.3 V) significant?

A: The forward voltage difference of 350 mV at 3 A represents a reduction in power dissipation. In a 3 A circuit, this translates to approximately 1.05 W lower dissipation per diode. This improvement is beneficial in power supply designs and reduces thermal management requirements. The lower forward voltage does not create compatibility issues; circuits designed for the original 1.3 V specification will operate with improved efficiency at 950 mV.

Q: Can SF35G and SF35GH be used interchangeably?

A: Yes, from an electrical and mechanical standpoint. Both parts are identical except for automotive qualification. The SF35GH includes AEC-Q101 certification, making it suitable for applications requiring automotive-grade components. In non-automotive applications, either part is acceptable. Selection should be based on application requirements and qualification documentation needs.

Q: What is the impact of reduced reverse leakage current (5 µA vs. 10 µA) in SF35G and SF35GH?

A: Reduced reverse leakage current decreases standby power consumption and improves circuit performance in high-impedance applications. In a 300 V circuit, the difference represents 1.5 mW lower leakage power per diode. This improvement is particularly beneficial in precision analog circuits and low-power applications but is not critical for general-purpose rectification.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts (HER304G-TP, SF35G, SF35GH) are ROHS3 compliant, meeting environmental and hazardous substance restrictions. The original HER304-TP is also ROHS3 compliant. No environmental or regulatory issues arise from substitution.

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