6A4 General Purpose Rectifier Diode Equivalent & Substitute Parts

Part Overview

The 6A4 is a general purpose rectifier diode rated for 400 V DC reverse voltage and 6 A average rectified current in an R-6 axial through-hole package. Manufactured by SMC Diode Solutions, this component is classified as obsolete. Due to its obsolete status, equivalent substitute parts from active manufacturers are necessary for new designs and ongoing production requirements. Substitute diodes must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating packaging and availability constraints.

Substiute Parts

6A4

SMC Diode SolutionsIn Stock: 10306A4 Datasheet

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6A4-TP

Micro Commercial CoIn Stock: 128516A4-TP Datasheet

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6A40G B0G

Taiwan Semiconductor CorporationIn Stock: 8306A40G B0G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 6A4 rectifier diode is determined by strict equivalence across the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Voltage - DC Reverse (Vr) (Max): 400 V minimum
• Current - Average Rectified (Io): 6 A minimum
• Mounting Type: Through Hole
• Package / Case: R-6, Axial

Secondary Compatibility Parameters:

• Voltage - Forward (Vf) (Max) @ If: 950 mV or lower @ 6 A
• Speed: Standard Recovery >500ns, > 200mA (Io)
• Current - Reverse Leakage @ Vr: 10 µA or lower @ 400 V
• Operating Temperature - Junction: Must encompass application requirements

Substitute parts must satisfy all primary criteria. Variations in secondary parameters are acceptable provided they do not degrade circuit performance. Parts with higher forward voltage drop, lower reverse voltage rating, or reduced current capacity are not suitable substitutes.

Parameter Comparison

Engineering Selection Recommendations

6A4-TP (Micro Commercial Co): This substitute maintains identical electrical specifications to the original 6A4 across voltage, current, forward voltage drop, and reverse leakage parameters. The R-6 axial package and through-hole mounting are identical. The operating temperature range is reduced to -55°C ~ 125°C compared to the original -65°C ~ 175°C. This part is classified as "Not For New Designs," indicating limited long-term availability. ROHS3 compliance is confirmed. Selection of this substitute is appropriate for legacy system maintenance where the reduced temperature range is acceptable.

6A40G B0G (Taiwan Semiconductor Corporation): This substitute meets all primary substitution criteria with 400 V reverse voltage, 6 A current rating, and R-6 axial through-hole package. Forward voltage is specified at 1 V @ 6 A, representing a 50 mV increase over the original specification. Capacitance is reduced to 60 pF, which may improve high-frequency performance in certain applications. Operating temperature range extends to -55°C ~ 150°C. Product status is Active, ensuring long-term availability and supply continuity. ROHS3 compliance is confirmed. This substitute is suitable for new designs and ongoing production applications where the slightly elevated forward voltage drop is acceptable.

Frequently Asked Questions (FAQ)

Q: Can the 6A4-TP substitute for the original 6A4 in all applications?

A: The 6A4-TP maintains electrical equivalence across voltage, current, and leakage specifications. The primary consideration is the reduced operating temperature range (-55°C ~ 125°C versus -65°C ~ 175°C). Applications operating below -55°C or above 125°C require evaluation against actual circuit requirements. The part is classified as "Not For New Designs," indicating potential future availability constraints.

Q: What is the difference between the 6A4-TP and 6A40G B0G substitutes?

A: Both parts satisfy the primary substitution criteria of 400 V reverse voltage and 6 A current rating in R-6 axial packages. The 6A40G B0G has a slightly higher forward voltage drop (1 V versus 950 mV @ 6 A) and lower capacitance (60 pF versus 150 pF). The 6A40G B0G is classified as Active, providing superior long-term availability compared to the 6A4-TP, which is "Not For New Designs."

Q: Is the R-6 axial package interchangeable between all three parts?

A: Yes. All three parts—the original 6A4, the 6A4-TP, and the 6A40G B0G—use the R-6 axial through-hole package. Physical dimensions and lead spacing are identical, allowing direct board-level substitution without layout modifications.

Q: Does the 50 mV increase in forward voltage drop for the 6A40G B0G affect circuit performance?

A: The 6A40G B0G specifies 1 V forward voltage drop at 6 A, compared to 950 mV for the original 6A4. This 50 mV difference results in approximately 0.3 W additional power dissipation at full current. Circuit evaluation is necessary to determine if thermal management or voltage regulation adjustments are required. For most general purpose rectification applications, this difference is within acceptable tolerance.

Q: What is the significance of the reduced capacitance in the 6A40G B0G?

A: The 6A40G B0G specifies 60 pF capacitance at 4 V, 1 MHz, compared to 150 pF for the original 6A4. Lower junction capacitance typically improves switching performance and reduces capacitive coupling effects at higher frequencies. This characteristic may provide performance benefits in high-frequency or switching applications without introducing compatibility issues.

Q: Which substitute should be selected for new product designs?

A: The 6A40G B0G from Taiwan Semiconductor Corporation is the recommended substitute for new designs. It maintains all primary electrical specifications, is classified as Active for long-term availability, and carries ROHS3 compliance certification. The 6A4-TP is classified as "Not For New Designs" and should be reserved for legacy system maintenance only.

Q: Are there compliance or regulatory differences between the substitutes?

A: Both substitute parts carry ROHS3 compliance and REACH Unaffected status, matching the regulatory profile of the original 6A4. ECCN and HTSUS classifications are identical across all three parts. No compliance barriers exist for substitution.