MR851RL Equivalent & Substitute Parts

Part Overview

The MR851RL is a general-purpose rectifier diode rated for 100 V DC reverse voltage and 3 A average rectified current in an axial through-hole package. Manufactured by onsemi, this component is classified as obsolete. Due to its obsolete status and limited availability relative to active alternatives, equivalent substitute parts are necessary for new designs and ongoing production requirements. Active alternatives maintain identical electrical ratings while offering improved compliance certifications and greater inventory availability.

Key Parameters

Parameter	Value
Voltage - DC Reverse (Vr) (Max)	100 V
Current - Average Rectified (Io)	3 A
Voltage - Forward (Vf) (Max) @ If	1.25 V @ 3 A
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)
Reverse Recovery Time (trr)	300 ns
Current - Reverse Leakage @ Vr	10 µA @ 100 V
Mounting Type	Through Hole
Package / Case	DO-201AA, DO-27, Axial
Operating Temperature - Junction	-65°C ~ 125°C
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the MR851RL are selected based on strict electrical and mechanical parameter matching. The primary substitution criteria are:

Electrical Parameters (Must Match):

Voltage - DC Reverse (Vr) (Max): 100 V
Current - Average Rectified (Io): 3 A
Mounting Type: Through Hole
Package / Case: Axial configuration (DO-201AA, DO-27, or DO-201AD)

Secondary Considerations (Allowable Variations):

Voltage - Forward (Vf) (Max) @ If: Variations within typical rectifier specifications
Speed Classification: Both Fast Recovery (≤ 500ns) and Standard Recovery (> 500ns) types are acceptable
Reverse Recovery Time (trr): Variations acceptable within rectifier classification
Current - Reverse Leakage @ Vr: Variations acceptable within specified voltage rating
Operating Temperature Range: Variations acceptable if minimum meets or exceeds -65°C and maximum meets or exceeds 125°C
Product Status: Active status preferred for ongoing availability

All substitute parts listed maintain the core 100 V / 3 A electrical specification and through-hole axial mounting configuration required for direct functional equivalence.

Parameter Comparison

Part Number	Manufacturer	Vr (Max)	Io	Vf (Max) @ If	Speed	trr	Ir @ Vr	Package	Temp Range	Status	RoHS
MR851RL	onsemi	100 V	3 A	1.25 V @ 3 A	Fast Recovery ≤ 500ns	300 ns	10 µA @ 100 V	DO-201AA, DO-27, Axial	-65°C ~ 125°C	Obsolete	Non-compliant
MR851RLG	onsemi	100 V	3 A	1.25 V @ 3 A	Fast Recovery ≤ 500ns	300 ns	10 µA @ 100 V	DO-201AA, DO-27, Axial	-65°C ~ 125°C	Active	ROHS3 Compliant
1N5401G	Good-Ark Semiconductor	100 V	3 A	1.1 V @ 3 A	Standard Recovery > 500ns	—	5 µA @ 100 V	DO-201AD, Axial	-55°C ~ 150°C	Active	ROHS3 Compliant
EGP30B	Fairchild Semiconductor	100 V	3 A	950 mV @ 3 A	Fast Recovery ≤ 500ns	50 ns	5 µA @ 100 V	DO-201AD, Axial	-65°C ~ 150°C	Active	—
GI501-E3/54	Vishay General Semiconductor - Diodes Division	100 V	3 A	1.1 V @ 9.4 A	Standard Recovery > 500ns	2 µs	5 µA @ 100 V	DO-201AD, Axial	-50°C ~ 150°C	Active	ROHS3 Compliant
GI501-E3/73	Vishay General Semiconductor - Diodes Division	100 V	3 A	1.1 V @ 9.4 A	Standard Recovery > 500ns	2 µs	5 µA @ 100 V	DO-201AD, Axial	-50°C ~ 150°C	Active	ROHS3 Compliant
UF3002-G	Comchip Technology	100 V	3 A	1 V @ 3 A	Fast Recovery ≤ 500ns	50 ns	5 µA @ 100 V	DO-201AA, DO-27, Axial	-55°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (Identical Specifications):

MR851RLG is the direct active equivalent to MR851RL. Both parts are manufactured by onsemi and share identical electrical parameters, package configuration, and temperature range. MR851RLG carries ROHS3 compliance certification, addressing regulatory requirements not met by the obsolete MR851RL. This part is the primary recommendation for direct substitution in existing designs.

Functional Equivalents (100 V / 3 A Rating):

The following parts maintain the core 100 V reverse voltage and 3 A average rectified current specifications and are suitable for applications where the MR851RL is specified:

1N5401G (Good-Ark Semiconductor): Active status with ROHS3 compliance. Operates across -55°C to 150°C. Forward voltage is lower (1.1 V @ 3 A) and recovery speed is standard (> 500ns). Package is DO-201AD.
EGP30B (Fairchild Semiconductor): Active status. Operates across -65°C to 150°C, matching the original temperature range. Features fast recovery (≤ 500ns) with 50 ns reverse recovery time. Forward voltage is 950 mV @ 3 A. Package is DO-201AD.
GI501-E3/54 and GI501-E3/73 (Vishay General Semiconductor - Diodes Division): Both active with ROHS3 compliance. Standard recovery speed (> 500ns). Operate across -50°C to 150°C. Forward voltage specified at 1.1 V @ 9.4 A. Package is DO-201AD.
UF3002-G (Comchip Technology): Active status with ROHS3 compliance. Fast recovery (≤ 500ns) with 50 ns reverse recovery time. Forward voltage is 1 V @ 3 A. Operates across -55°C to 125°C. Package configuration includes DO-27 option, matching original package options.

Compliance Considerations:

All substitute parts listed carry ROHS3 compliance or are unaffected by REACH regulations. The original MR851RL is RoHS non-compliant. Selection of compliant alternatives ensures compatibility with current regulatory requirements for new designs and production.

Inventory Availability:

MR851RLG offers the highest inventory availability (7500 pcs) among active alternatives. GI501-E3/54 provides 6324 pcs, EGP30B provides 3382 pcs, 1N5401G provides 1346 pcs, and UF3002-G provides 852 pcs.

Frequently Asked Questions (FAQ)

Q: Can MR851RLG be used as a direct replacement for MR851RL?

A: Yes. MR851RLG is the direct active equivalent manufactured by onsemi. Both parts share identical electrical specifications (100 V, 3 A, fast recovery ≤ 500ns, 300 ns reverse recovery time), package configuration (DO-201AA, DO-27, Axial), and operating temperature range (-65°C ~ 125°C). The primary difference is product status (Active vs. Obsolete) and RoHS compliance (ROHS3 vs. Non-compliant).

Q: What are the key electrical parameters that determine substitution compatibility?

A: The primary parameters are Voltage - DC Reverse (Vr) (Max) of 100 V and Current - Average Rectified (Io) of 3 A. All listed substitutes maintain these specifications. Secondary parameters including forward voltage, recovery speed, and reverse leakage current vary among alternatives but remain within acceptable ranges for general-purpose rectifier applications. Mounting type (Through Hole) and package configuration (Axial) must also be maintained.

Q: Are there package differences between substitute parts?

A: Yes. The original MR851RL is available in DO-201AA, DO-27, and Axial configurations. Most substitutes use DO-201AD package, which is mechanically and electrically compatible with DO-201AA in axial through-hole applications. UF3002-G maintains DO-27 availability. Verify physical dimensions and lead spacing for your specific PCB layout before selection.

Q: What is the difference between Fast Recovery and Standard Recovery diodes?

A: Fast Recovery diodes have reverse recovery time ≤ 500ns, while Standard Recovery diodes exceed 500ns. The MR851RL specifies Fast Recovery (300 ns). Substitutes EGP30B and UF3002-G maintain Fast Recovery characteristics. Substitutes 1N5401G, GI501-E3/54, and GI501-E3/73 use Standard Recovery (> 500ns or 2 µs). Standard Recovery diodes are suitable for lower-frequency applications and general-purpose rectification where switching speed is not critical.

Q: Do all substitute parts meet RoHS compliance?

A: All listed substitute parts carry ROHS3 compliance or are REACH Unaffected. The original MR851RL is RoHS non-compliant. For new designs and production subject to RoHS regulations, any of the listed substitutes are acceptable. MR851RLG is the recommended choice for direct replacement with compliance certification.

Q: What is the operating temperature range difference between substitutes?

A: The original MR851RL operates from -65°C to 125°C. Substitutes vary: 1N5401G operates -55°C to 150°C, EGP30B operates -65°C to 150°C, GI501-E3/54 and GI501-E3/73 operate -50°C to 150°C, and UF3002-G operates -55°C to 125°C. For applications requiring the full -65°C minimum, EGP30B is the preferred alternative among non-onsemi options.

Q: Can I use a substitute with lower forward voltage?

A: Yes. Lower forward voltage (such as EGP30B at 950 mV vs. MR851RL at 1.25 V) results in reduced power dissipation and heat generation. This is generally beneficial in rectifier applications. Verify that your circuit design does not depend on the specific forward voltage characteristic of the original part.

Q: Which substitute offers the best inventory availability?

A: MR851RLG offers 7500 pcs in stock, followed by GI501-E3/54 with 6324 pcs. For applications requiring immediate availability of large quantities, these two options provide the shortest lead times.

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