SD103B Schottky Diode Equivalent & Substitute Parts

Part Overview

The SD103B is a Schottky rectifier diode manufactured by Diodes Incorporated, rated for 30 V DC reverse voltage and 350 mA average rectified current in a through-hole DO-35 package. This component is discontinued at DiGi Electronics, necessitating identification of equivalent and substitute parts for ongoing design requirements and production needs. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives with modified parameters suitable for specific application requirements.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	30	V
Current - Average Rectified (Io)	350	mA
Voltage - Forward (Vf) (Max) @ If	600 mV @ 200 mA	mV @ mA
Reverse Recovery Time (trr)	10	ns
Current - Reverse Leakage @ Vr	5	µA @ 20 V
Capacitance @ Vr, F	50	pF @ 0V, 1MHz
Mounting Type	Through Hole	-
Package / Case	DO-204AH, DO-35, Axial	-
Operating Temperature - Junction (Max)	125	°C
Technology	Schottky	-

Substitute Part Grouping Explanation

Substitution of the SD103B is determined by the following critical parameters: maximum reverse voltage (Vr), average rectified current (Io), forward voltage drop (Vf), reverse recovery time (trr), and package type. Parts are grouped into three categories based on substitution relationship:

Direct Equivalent (Same Electrical & Mechanical Specifications): Parts maintaining 30 V reverse voltage, 350 mA current rating, 600 mV forward voltage, 10 ns recovery time, and DO-35 through-hole package.

Functional Equivalent (Same Voltage & Current, Different Package): Parts with identical 30 V and 350 mA ratings but surface-mount packaging, suitable for designs permitting package migration.

Parametric Substitute (Modified Ratings, Same Package): Parts with altered voltage or current specifications but compatible through-hole DO-35 packaging, applicable where design margins permit specification changes.

Parameter Comparison

Part Number	Manufacturer	Vr (Max) [V]	Io [mA]	Vf (Max) @ If [mV @ mA]	trr [ns]	Ir @ Vr [µA]	Package Type	Mounting	Product Status
SD103B	Diodes Incorporated	30	350	600 @ 200	10	5 @ 20V	DO-35	Through Hole	Discontinued
SD103BW-7-F	Diodes Incorporated	30	350	600 @ 200	10	5 @ 20V	SOD-123	Surface Mount	Active
SD103B-F	Diodes Incorporated	30	350	600 @ 200	10	5 @ 20V	DO-35	Through Hole	Discontinued
BAT42	STMicroelectronics	30	200	1000 @ 200	5	500 nA @ 25V	DO-35	Through Hole	Active
BAT43	STMicroelectronics	30	200	1000 @ 200	5	500 nA @ 25V	DO-35	Through Hole	Active
BAT48	STMicroelectronics	40	350	750 @ 200	10	25 @ 40V	DO-35	Through Hole	Active
SD103B-TR	Vishay General Semiconductor - Diodes Division	30	—	600 @ 200	10	5 @ 20V	DO-35	Through Hole	Active

Engineering Selection Recommendations

SD103B-F (Diodes Incorporated): Direct parametric equivalent with identical electrical specifications and DO-35 through-hole package. Discontinued status limits availability. RoHS3 compliant.

SD103BW-7-F (Diodes Incorporated): Maintains all electrical parameters of the SD103B with identical 30 V, 350 mA, and 600 mV specifications. Surface-mount SOD-123 package requires PCB redesign. Active product status with RoHS3 compliance. Suitable for new designs permitting package migration.

SD103B-TR (Vishay General Semiconductor - Diodes Division): Maintains 30 V reverse voltage, 600 mV forward voltage, and 10 ns recovery time in DO-35 through-hole package. Average rectified current not specified in available data. Active product status with RoHS3 compliance. Compatible footprint for direct replacement.

BAT42 and BAT43 (STMicroelectronics): Both parts maintain 30 V reverse voltage in DO-35 through-hole package. Current rating reduced to 200 mA (57% of SD103B rating). Forward voltage increased to 1000 mV (67% higher than SD103B). Reverse recovery time reduced to 5 ns. Active product status with RoHS3 compliance. Applicable only where 200 mA current capacity is sufficient.

BAT48 (STMicroelectronics): Maintains 350 mA current rating and 10 ns recovery time in DO-35 through-hole package. Reverse voltage increased to 40 V (33% higher than SD103B). Forward voltage increased to 750 mV (25% higher than SD103B). Active product status with RoHS3 compliance. Suitable for applications requiring higher voltage margin.

Frequently Asked Questions (FAQ)

Q: Can SD103B-F be used as a direct replacement for SD103B?

A: SD103B-F is a parametric equivalent with identical electrical specifications (30 V, 350 mA, 600 mV forward voltage, 10 ns recovery time) and DO-35 through-hole package. Both parts are discontinued at DiGi Electronics, limiting practical availability.

Q: What is the primary difference between SD103BW-7-F and SD103B?

A: SD103BW-7-F maintains all electrical parameters of SD103B but uses surface-mount SOD-123 packaging instead of through-hole DO-35. This requires PCB redesign and assembly process modification. SD103BW-7-F is currently active.

Q: Can BAT42 or BAT43 replace SD103B in all applications?

A: BAT42 and BAT43 are not direct replacements. Both parts reduce current capacity to 200 mA (from 350 mA) and increase forward voltage to 1000 mV (from 600 mV). These parts are suitable only for applications where the reduced current rating and higher forward voltage drop are acceptable.

Q: What advantage does BAT48 offer over SD103B?

A: BAT48 maintains the 350 mA current rating and 10 ns recovery time but increases reverse voltage rating to 40 V. This provides additional voltage margin for applications operating near the 30 V limit. Forward voltage is increased to 750 mV.

Q: Is SD103B-TR a suitable replacement for SD103B?

A: SD103B-TR maintains 30 V reverse voltage, 600 mV forward voltage, and 10 ns recovery time in DO-35 through-hole package. Average rectified current is not specified in available documentation. The part is currently active and RoHS3 compliant, making it a potential alternative where current specification can be verified.

Q: What are the RoHS compliance differences between these parts?

A: SD103B is RoHS non-compliant. All substitute parts (SD103B-F, SD103BW-7-F, BAT42, BAT43, BAT48, SD103B-TR) are RoHS3 compliant, meeting current environmental regulations for new designs and production.

Q: Which substitute part has the lowest reverse leakage current?

A: BAT42 and BAT43 exhibit the lowest reverse leakage at 500 nanoamperes at 25 V, compared to 5 microamperes at 20 V for SD103B. BAT48 shows 25 microamperes at 40 V. Lower leakage current may be beneficial in high-impedance circuit applications.

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

A: Only SD103B-F and SD103B-TR maintain DO-35 through-hole package compatibility with existing SD103B PCB layouts. SD103BW-7-F requires surface-mount PCB redesign. BAT42, BAT43, and BAT48 are compatible with DO-35 footprints but have modified electrical specifications requiring circuit analysis.

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