RB420D-TP Equivalent & Substitute Parts

Part Overview

The RB420D-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 part is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and procurement continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives with modified performance characteristics within acceptable application parameters.

Key Parameters

Parameter	Value	Specification Basis
Voltage - DC Reverse (Vr) (Max)	40 V	Primary voltage rating
Current - Average Rectified (Io)	100 mA	Primary current rating
Voltage - Forward (Vf) (Max) @ If	450 mV @ 10 mA	Forward conduction characteristic
Technology	Schottky	Diode type classification
Package / Case	TO-236-3, SC-59, SOT-23-3	Physical form factor
Mounting Type	Surface Mount	Assembly method
Operating Temperature - Junction (Max)	125°C	Thermal rating
Current - Reverse Leakage @ Vr	1 µA @ 10 V	Leakage characteristic
Capacitance @ Vr, F	6 pF @ 10V, 1MHz	Junction capacitance
RoHS Status	ROHS3 Compliant	Environmental compliance
Moisture Sensitivity Level (MSL)	1 (Unlimited)	Handling requirement

Substitute Part Grouping Explanation

Substitution of the RB420D-TP is determined by the following critical parameters:

Voltage Rating Requirement: All substitute parts must maintain a DC reverse voltage rating of 40 V or greater to ensure safe operation within the original circuit design envelope.

Package Compatibility: All substitute parts must use the TO-236-3 / SC-59 / SOT-23-3 package form factor to ensure mechanical and electrical compatibility with existing PCB layouts and assembly processes.

Technology Classification: All substitute parts must be Schottky diodes to maintain the forward voltage and switching characteristics required by the application.

Current Rating Consideration: Substitute parts may have current ratings equal to or greater than 100 mA. Higher current ratings provide design margin and do not compromise circuit function when the application current demand does not exceed the original 100 mA specification.

Surface Mount Assembly: All substitute parts must be surface mount devices to maintain compatibility with modern manufacturing processes.

Compliance Standards: All substitute parts must maintain ROHS3 compliance and MSL 1 rating to ensure environmental and handling compatibility.

Parameter Comparison

Part Number	Manufacturer	Vr (Max)	Io (mA)	Vf (Max) @ If	Package	Temp (Max)	Status	Leakage @ Vr
RB420D-TP	Micro Commercial Co	40 V	100	450 mV @ 10 mA	SOT-23-3	125°C	Obsolete	1 µA @ 10 V
BAS40,215	Nexperia USA Inc.	40 V	120	1 V @ 40 mA	TO-236AB	150°C	Active	10 µA @ 40 V
BAS40,235	Nexperia USA Inc.	40 V	120	1 V @ 40 mA	TO-236AB	150°C	Active	10 µA @ 40 V
BAS40-7-F	Diodes Incorporated	40 V	200	1 V @ 40 mA	SOT-23-3	125°C	Active	200 nA @ 30 V
BAT720,215	Nexperia USA Inc.	40 V	500	550 mV @ 500 mA	TO-236AB	125°C	Active	100 µA @ 35 V
BAT720,235	Nexperia USA Inc.	40 V	500	550 mV @ 500 mA	TO-236AB	125°C	Active	100 µA @ 35 V
BAT721,215	Nexperia USA Inc.	40 V	200	550 mV @ 200 mA	TO-236AB	125°C	Active	15 µA @ 30 V
PMEG4005ET,215	Nexperia USA Inc.	40 V	500	470 mV @ 500 mA	TO-236AB	150°C	Active	100 µA @ 40 V
PMEG4010ET,215	Nexperia USA Inc.	40 V	1000	640 mV @ 1 A	TO-236AB	150°C	Active	100 µA @ 40 V
RB421DFHT146	Rohm Semiconductor	40 V	100	550 mV @ 100 mA	SMD3	125°C	Not For New Designs	30 µA @ 10 V
RB420DFHT146	Rohm Semiconductor	40 V	100	450 mV @ 10 mA	SMD3	125°C	Not For New Designs	1 µA @ 10 V

Engineering Selection Recommendations

Parametric Equivalent (Direct Replacement):

RB420DFHT146 from Rohm Semiconductor provides parametric equivalence to the RB420D-TP with identical voltage rating (40 V), current rating (100 mA), forward voltage characteristic (450 mV @ 10 mA), and reverse leakage (1 µA @ 10 V). Both parts share the same operating temperature maximum of 125°C and maintain ROHS3 compliance. The RB420DFHT146 is classified as "Not For New Designs" but remains available for legacy system support and repair applications. The SMD3 package designation is mechanically and electrically equivalent to SOT-23-3.

Active Substitute with Increased Current Rating:

BAS40-7-F from Diodes Incorporated maintains the 40 V voltage rating and SOT-23-3 package compatibility while providing doubled current capacity (200 mA versus 100 mA). This part is in active production status and offers superior reverse leakage performance (200 nA @ 30 V). The forward voltage specification differs at the measurement point (1 V @ 40 mA versus 450 mV @ 10 mA), but both values remain within acceptable Schottky diode operating ranges. This part is suitable for applications requiring enhanced current margin.

Active Substitutes with Higher Current Ratings:

BAT720,215, BAT720,235, PMEG4005ET,215, and PMEG4010ET,215 from Nexperia USA Inc. provide 40 V voltage rating compatibility with progressively higher current ratings (500 mA to 1 A). These parts are in active production and offer enhanced thermal performance with maximum junction temperatures of 125°C to 150°C. These substitutes are appropriate for applications where the original 100 mA specification provides insufficient design margin or where future current demand expansion is anticipated.

Automotive-Qualified Alternatives:

BAS40,215 and BAS40,235 from Nexperia USA Inc., along with BAT721,215, carry automotive grade designation and AEC-Q100 qualification. These parts are suitable for applications requiring automotive-level reliability and traceability. Both maintain 40 V voltage rating with current ratings of 120 mA to 200 mA and are in active production status.

Avoidance Criteria:

RB421DFHT146 from Rohm Semiconductor is classified as "Not For New Designs" and should not be selected for new circuit implementations, although it remains available for legacy system maintenance.

Frequently Asked Questions (FAQ)

Q: Can BAS40-7-F directly replace RB420D-TP in existing designs?

A: Yes. BAS40-7-F maintains the critical 40 V voltage rating and SOT-23-3 package form factor. The doubled current rating (200 mA versus 100 mA) provides design margin without compromising circuit function. Forward voltage characteristics differ at the measurement point but remain within acceptable Schottky diode operating ranges.

Q: What is the difference between TO-236AB and SOT-23-3 package designations?

A: TO-236AB and SOT-23-3 are equivalent package designations for the same three-lead surface mount form factor. Both refer to the same physical dimensions and pin configuration. Parts specified with either designation are mechanically and electrically interchangeable.

Q: Why do some substitute parts have higher reverse leakage current specifications?

A: Reverse leakage current varies among manufacturers and process technologies. Higher leakage specifications (such as 10 µA versus 1 µA) remain within acceptable limits for most applications and do not indicate inferior performance. Application-specific requirements should determine whether leakage specifications are critical.

Q: Are Nexperia BAS40 and BAT720 series parts suitable for high-reliability applications?

A: Nexperia parts designated with automotive grade and AEC-Q100 qualification (BAS40,215, BAS40,235, BAT721,215) are suitable for high-reliability applications. Non-automotive variants remain suitable for general industrial and consumer applications where automotive qualification is not required.

Q: What is the significance of "Not For New Designs" status on Rohm parts?

A: "Not For New Designs" indicates that the manufacturer no longer recommends these parts for new circuit implementations. However, these parts remain available for legacy system support, repair, and maintenance. New designs should select from parts with "Active" status.

Q: Can PMEG4010ET,215 (1 A rating) be used in place of RB420D-TP (100 mA rating)?

A: Yes. The PMEG4010ET,215 maintains the 40 V voltage rating and TO-236AB package compatibility. The significantly higher current rating (1 A versus 100 mA) provides substantial design margin. Forward voltage increases at higher current levels (640 mV @ 1 A), but this does not prevent substitution in applications where the original 100 mA specification is adequate.

Q: What packaging options are available for RB420D-TP substitutes?

A: Substitute parts are available in Tape & Reel (TR) and Cut Tape (CT) & Digi-Reel® packaging formats. Selection between packaging options depends on procurement volume and assembly process requirements. Both formats contain identical components; packaging differences affect only handling and delivery logistics.

Q: Are all listed substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed maintain ROHS3 compliance and MSL 1 (Unlimite

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