1N5821 Schottky Diode Equivalent & Substitute Parts

Part Overview

The 1N5821 is a Schottky rectifier diode manufactured by STMicroelectronics, rated for 30 V DC reverse voltage and 3 A average rectified current in a through-hole DO-201AD axial package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Schottky diodes are fast-recovery rectifiers commonly used in power supply circuits, reverse polarity protection, and high-frequency switching applications where low forward voltage drop and rapid switching characteristics are required.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	30	V
Current - Average Rectified (Io)	3	A
Voltage - Forward (Vf) (Max) @ If	500 mV @ 3 A	mV
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	2	mA @ 30 V
Mounting Type	Through Hole	—
Package / Case	DO-201AD, Axial	—
Operating Temperature - Junction (Max)	150	°C
Technology	Schottky	—

Substitute Part Grouping Explanation

Substitute parts for the 1N5821 are grouped into two categories based on electrical and mechanical compatibility:

Category 1: Direct Electrical Equivalents (Same Voltage and Current Ratings)

Parts meeting the core electrical specifications of 30 V reverse voltage and 3 A average rectified current with identical forward voltage characteristics (500 mV @ 3 A) and fast recovery speed (≤ 500ns) are classified as direct equivalents. These parts maintain the same functional performance in circuits designed for the 1N5821.

Key parameters for equivalence:

Voltage - DC Reverse (Vr) (Max): 30 V
Current - Average Rectified (Io): 3 A
Voltage - Forward (Vf) (Max) @ If: 500 mV @ 3 A
Speed: Fast Recovery ≤ 500ns, > 200mA (Io)
Mounting Type: Through Hole
Package / Case: DO-201AD or compatible axial package

Category 2: Higher Voltage Rating Alternatives

Parts with elevated reverse voltage ratings (40 V) maintain compatibility with 30 V circuit designs while providing additional voltage margin. These parts are suitable for applications requiring enhanced overvoltage protection.

Category 3: Surface Mount Alternatives

Parts with different mounting technology (surface mount) and reduced current ratings (750 mA) are listed for reference in applications where package form factor differs from the original through-hole requirement.

Parameter Comparison

Part Number	Manufacturer	Vr (Max)	Io	Vf (Max) @ If	Speed	Ir @ Vr	Package	Mounting	Tj (Max)	Status
1N5821	STMicroelectronics	30 V	3 A	500 mV @ 3 A	≤ 500ns	2 mA @ 30 V	DO-201AD	Through Hole	150°C	Obsolete
1N5821-AP	Micro Commercial Co	30 V	3 A	500 mV @ 3 A	≤ 500ns	500 µA @ 30 V	DO-201AD	Through Hole	125°C	Active
1N5821-BP	Micro Commercial Co	30 V	3 A	500 mV @ 3 A	≤ 500ns	500 µA @ 30 V	DO-201AD	Through Hole	125°C	Active
1N5821-TP	Micro Commercial Co	30 V	3 A	500 mV @ 3 A	≤ 500ns	500 µA @ 30 V	DO-201AD	Through Hole	125°C	Active
1N5821RLG	onsemi	30 V	3 A	500 mV @ 3 A	≤ 500ns	2 mA @ 30 V	DO-201AA / DO-27	Through Hole	125°C	Active
1N5822	Microchip Technology	40 V	3 A	500 mV @ 3 A	≤ 500ns	100 µA @ 40 V	B, Axial	Through Hole	125°C	Active
ZHCS750TA	Diodes Incorporated	40 V	750 mA	490 mV @ 750 mA	≤ 500ns	100 µA @ 30 V	SOT-23-3	Surface Mount	125°C	Active

Engineering Selection Recommendations

For Direct Replacement (Same Electrical and Mechanical Specifications):

The 1N5821-TP (Micro Commercial Co) is the primary recommended substitute. This part maintains identical electrical ratings (30 V, 3 A, 500 mV forward voltage) and package configuration (DO-201AD through-hole axial). The part is active in production with ROHS3 compliance and unlimited moisture sensitivity level. Inventory availability is 6005 units.

The 1N5821RLG (onsemi) provides an alternative direct replacement with identical electrical specifications and active product status. This part features compatible axial packaging (DO-201AA / DO-27) and ROHS3 compliance. Inventory availability is 4654 units.

For Applications Requiring Enhanced Voltage Margin:

The 1N5822 (Microchip Technology) is suitable for circuits where additional reverse voltage headroom is beneficial. This part maintains the 3 A current rating and 500 mV forward voltage characteristic while providing 40 V reverse voltage rating. The part is active in production with high inventory availability (26834 units). Note: RoHS non-compliant status applies to this part.

For Surface Mount Applications:

The ZHCS750TA (Diodes Incorporated) is applicable only to designs requiring surface mount technology. This part operates at reduced current rating (750 mA) and is not suitable for direct replacement in through-hole circuits designed for 3 A operation. The part is active in production with ROHS3 compliance and high inventory availability (22879 units).

For Bulk Packaging Options:

The 1N5821-AP and 1N5821-BP (Micro Commercial Co) provide bulk packaging alternatives to the cut-tape format. Both parts maintain identical electrical specifications to the 1N5821-TP and are active in production with ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can the 1N5821-TP be used as a direct replacement for the obsolete 1N5821?

A: Yes. The 1N5821-TP maintains identical electrical specifications (30 V reverse voltage, 3 A average rectified current, 500 mV forward voltage at 3 A) and package configuration (DO-201AD through-hole axial). The part is active in production and ROHS3 compliant.

Q: What is the difference between 1N5821-AP, 1N5821-BP, and 1N5821-TP?

A: These three parts are electrically identical and differ only in packaging format. The -AP and -BP variants are supplied in bulk packaging, while the -TP variant is supplied in cut tape format. Selection depends on procurement and assembly requirements.

Q: Can the 1N5822 replace the 1N5821 in existing circuits?

A: The 1N5822 is electrically compatible for circuits designed for 30 V operation, as it maintains the same 3 A current rating and 500 mV forward voltage characteristic. The 1N5822 provides a higher 40 V reverse voltage rating, which adds voltage margin but does not affect circuit operation at 30 V. However, the 1N5822 is RoHS non-compliant, which may impact procurement decisions based on regulatory requirements.

Q: Is the ZHCS750TA suitable as a replacement for the 1N5821?

A: The ZHCS750TA is not suitable for direct replacement. While both parts are Schottky diodes with fast recovery characteristics, the ZHCS750TA is rated for only 750 mA average rectified current compared to the 1N5821's 3 A rating. Additionally, the ZHCS750TA uses surface mount technology (SOT-23-3 package) rather than through-hole axial mounting. The ZHCS750TA is applicable only to new designs requiring surface mount components with lower current requirements.

Q: What is the significance of the reverse leakage current difference between the 1N5821 and 1N5821-TP?

A: The 1N5821 specifies 2 mA reverse leakage at 30 V, while the 1N5821-TP specifies 500 µA at the same voltage. Lower reverse leakage current reduces power dissipation in reverse bias conditions and improves circuit efficiency. The 1N5821-TP's lower leakage is advantageous for applications sensitive to standby power consumption.

Q: Are all substitute parts ROHS3 compliant?

A: No. The 1N5822 (Microchip Technology) is RoHS non-compliant. All other substitute parts listed (1N5821-AP, 1N5821-BP, 1N5821-TP, 1N5821RLG, and ZHCS750TA) are ROHS3 compliant.

Q: What is the operating temperature range difference between the 1N5821 and its substitutes?

A: The original 1N5821 specifies a maximum junction temperature of 150°C. Most active substitutes (1N5821-AP, 1N5821-BP, 1N5821-TP, 1N5821RLG, 1N5822, and ZHCS750TA) specify a maximum junction temperature of 125°C. This difference may impact thermal design in high-temperature applications. The 1N5821RLG extends the lower temperature limit to -65°C compared to the original part's unspecified lower limit.

Q: Can the 1N5821RLG be used interchangeably with the 1N5821-TP?

A: Yes, for most applications. Both parts maintain identical electrical specifications (30 V, 3 A, 500 mV forward voltage) and through-hole axial mounting. The 1N5821RLG uses DO-201AA / DO-27 packaging, which is mechanically compatible with DO-201AD. Both parts are ROHS3 compliant and active in production.

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