RB421D-TP Equivalent & Substitute Parts

Part Overview

The RB421D-TP is a Schottky rectifier diode manufactured by Micro Commercial Co, rated for 40 V DC reverse voltage and 100 mA average rectified current in a surface mount SOT-23 package. This component is classified as obsolete, necessitating identification of equivalent and substitute parts for ongoing design support and procurement continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives within acceptable parameter ranges for the application category.

Key Parameters

Parameter	Value	Unit
Technology	Schottky	—
Voltage - DC Reverse (Vr) (Max)	40	V
Current - Average Rectified (Io)	100	mA
Voltage - Forward (Vf) (Max) @ If	550 mV @ 100 mA	—
Current - Reverse Leakage @ Vr	30 µA @ 10 V	—
Capacitance @ Vr, F	6 pF @ 10 V, 1 MHz	—
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—
Operating Temperature - Junction (Max)	125	°C
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the RB421D-TP is determined by the following critical parameters:

Electrical Compatibility Criteria:

Voltage - DC Reverse (Vr) (Max): Must equal or exceed 40 V
Current - Average Rectified (Io): Must equal or exceed 100 mA
Technology: Schottky diode classification
Forward voltage characteristics: Must be compatible with circuit design requirements

Mechanical Compatibility Criteria:

Package / Case: TO-236-3, SC-59, SOT-23-3 (surface mount)
Mounting Type: Surface Mount
Moisture Sensitivity Level: MSL 1 (Unlimited)

Compliance Criteria:

RoHS Status: ROHS3 Compliant
REACH Status: REACH Unaffected

Substitute parts are grouped into two categories: parametric equivalents (identical electrical specifications) and functional substitutes (equal or superior current ratings with identical voltage ratings).

Parameter Comparison

Parameter	RB421D-TP (Main)	RB421DT146	RB421DFHT146	RB420DFHT146	BAS40-7-F
Manufacturer	Micro Commercial Co	Rohm Semiconductor	Rohm Semiconductor	Rohm Semiconductor	Diodes Incorporated
Product Status	Obsolete	Active	Not For New Designs	Not For New Designs	Active
Voltage - DC Reverse (Vr) (Max)	40 V	40 V	40 V	40 V	40 V
Current - Average Rectified (Io)	100 mA	100 mA	100 mA	100 mA	200 mA
Voltage - Forward (Vf) (Max) @ If	550 mV @ 100 mA	550 mV @ 100 mA	550 mV @ 100 mA	450 mV @ 10 mA	1 V @ 40 mA
Current - Reverse Leakage @ Vr	30 µA @ 10 V	30 µA @ 10 V	30 µA @ 10 V	1 µA @ 10 V	200 nA @ 30 V
Capacitance @ Vr, F	6 pF @ 10 V, 1 MHz	6 pF @ 10 V, 1 MHz	6 pF @ 10 V, 1 MHz	6 pF @ 10 V, 1 MHz	5 pF @ 0 V, 1 MHz
Package / Case	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3	TO-236-3, SC-59, SOT-23-3
Operating Temperature - Junction (Max)	125°C	125°C	125°C	125°C	125°C
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Parametric Equivalent (Recommended for Direct Replacement):

RB421DT146 manufactured by Rohm Semiconductor is the primary parametric equivalent. This part maintains identical electrical specifications including 40 V reverse voltage, 100 mA average rectified current, and 550 mV forward voltage at 100 mA. The RB421DT146 holds Active product status, ensuring long-term availability and supply chain continuity. This part is suitable for new designs and provides direct functional replacement without circuit modification.

Alternative Equivalent (Tape & Reel Packaging):

RB421DFHT146 manufactured by Rohm Semiconductor provides identical electrical parameters to the main part and is available in Tape & Reel packaging. This part is classified as Not For New Designs but remains available for legacy system support and repair applications. Electrical compatibility is complete across all critical parameters.

Functional Substitute (Enhanced Current Rating):

BAS40-7-F manufactured by Diodes Incorporated provides a functional substitute with superior current handling capability (200 mA versus 100 mA) while maintaining the 40 V reverse voltage rating. This part is Active and suitable for new designs. The higher current rating provides design margin for applications requiring increased current capacity. Forward voltage characteristics differ at the specified test point but remain within acceptable Schottky diode performance ranges.

Alternative Functional Substitute (Automotive Grade):

RB420DFHT146 manufactured by Rohm Semiconductor provides identical 40 V and 100 mA specifications with improved reverse leakage characteristics (1 µA @ 10 V versus 30 µA @ 10 V). This part carries AEC-Q101 automotive qualification and is classified as Not For New Designs. Selection of this part is appropriate for automotive applications requiring enhanced reliability certification.

Frequently Asked Questions (FAQ)

Q: Can RB421DT146 be used as a direct replacement for RB421D-TP?

A: Yes. RB421DT146 is a parametric equivalent with identical voltage rating (40 V), current rating (100 mA), forward voltage (550 mV @ 100 mA), and package type (SOT-23-3). No circuit modification is required. RB421DT146 holds Active product status, ensuring availability for ongoing production.

Q: What is the difference between RB421DT146 and RB421DFHT146?

A: Both parts are manufactured by Rohm Semiconductor and provide identical electrical specifications. The primary difference is packaging format: RB421DT146 is supplied in Cut Tape (CT) & Digi-Reel format, while RB421DFHT146 is supplied in Tape & Reel (TR) format. Both are parametric equivalents to the RB421D-TP.

Q: Can BAS40-7-F replace RB421D-TP in all applications?

A: BAS40-7-F is a functional substitute with identical 40 V reverse voltage rating but double the current capacity (200 mA versus 100 mA). The higher current rating provides design margin and is compatible with applications designed for 100 mA operation. Forward voltage characteristics differ slightly but remain within acceptable Schottky diode performance parameters. BAS40-7-F is Active and suitable for new designs.

Q: Why is RB420DFHT146 listed as an alternative?

A: RB420DFHT146 provides identical 40 V and 100 mA specifications with superior reverse leakage performance (1 µA @ 10 V versus 30 µA @ 10 V). This part carries AEC-Q101 automotive qualification, making it suitable for automotive applications requiring enhanced reliability certification. It is classified as Not For New Designs but remains available for legacy and automotive system support.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts (RB421DT146, RB421DFHT146, RB420DFHT146, and BAS40-7-F) are ROHS3 Compliant and REACH Unaffected, matching the compliance status of the RB421D-TP.

Q: What is the significance of MSL 1 (Unlimited) rating?

A: Moisture Sensitivity Level 1 (Unlimited) indicates that these components have no moisture sensitivity restrictions. They do not require special moisture control during storage, handling, or assembly, simplifying procurement and manufacturing processes.

Q: Can these parts be used interchangeably in existing PCB designs?

A: Yes, all substitute parts use identical SOT-23-3 package geometry (TO-236-3, SC-59). PCB footprints and assembly processes require no modification. Electrical compatibility is maintained across all critical parameters for the specified application category.

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