BAT47 Equivalent & Substitute Parts

Part Overview

The BAT47 is a Schottky rectifier diode manufactured by STMicroelectronics, rated for 20 V DC reverse voltage and 350 mA average rectified current in a DO-35 through-hole package. This component is classified as obsolete, though 16,900 units remain in stock as new original inventory. The BAT47 exhibits fast recovery characteristics with switching speed ≤ 500 ns at currents exceeding 200 mA, making it suitable for high-frequency rectification applications. Due to its obsolete status, identification of equivalent and substitute parts is necessary for design continuity, long-term supply assurance, and potential performance optimization in new production runs.

Key Parameters

Parameter	BAT47 Specification
Voltage - DC Reverse (Vr) (Max)	20 V
Current - Average Rectified (Io)	350 mA
Voltage - Forward (Vf) (Max) @ If	1 V @ 300 mA
Speed Classification	Fast Recovery ≤ 500 ns, > 200 mA (Io)
Current - Reverse Leakage @ Vr	10 µA @ 20 V
Capacitance @ Vr, F	20 pF @ 0 V, 1 MHz
Package / Case	DO-204AH, DO-35, Axial
Mounting Type	Through Hole
Operating Temperature - Junction	-65°C ~ 125°C
RoHS Status	ROHS3 Compliant
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the BAT47 is determined by the following critical parameters: reverse voltage rating (Vr), average rectified current capacity (Io), forward voltage drop (Vf), switching speed classification, and package form factor. The BAT47 operates at 20 V maximum reverse voltage with 350 mA current handling and fast recovery switching characteristics.

Substitute parts are grouped into three categories based on electrical compatibility:

Category 1: Direct Current Rating Substitutes (350 mA or Higher) Parts in this category maintain the 20 V reverse voltage specification and support the full 350 mA current requirement or exceed it. These parts preserve the electrical operating envelope of the original BAT47 design.

Category 2: Reduced Current Substitutes (75 mA to 200 mA) Parts in this category maintain the 20 V reverse voltage but operate at reduced current ratings. These are suitable only for applications where the actual circuit current demand is lower than the BAT47's 350 mA rating.

Category 3: Elevated Voltage Substitutes (30 V) Parts in this category exceed the 20 V reverse voltage specification while maintaining compatible current ratings. These provide additional voltage margin and are electrically compatible with 20 V designs.

Category 4: Higher Current Substitutes (1 A) Parts in this category exceed both the voltage and current specifications of the BAT47, providing design flexibility for applications requiring higher current capacity.

Parameter Comparison

Part Number	Manufacturer	Vr (Max)	Io (mA)	Vf (Max) @ If	Speed	Package	Product Status	RoHS Status
BAT47	STMicroelectronics	20 V	350	1 V @ 300 mA	Fast Recovery ≤ 500 ns, > 200 mA	DO-35	Obsolete	ROHS3 Compliant
1N5712	Microchip Technology	20 V	75	1 V @ 35 mA	Small Signal ≤ 200 mA, Any Speed	DO-35	Active	RoHS non-compliant
1N5712-1	Microchip Technology	20 V	75	1 V @ 35 mA	Small Signal ≤ 200 mA, Any Speed	DO-35	Active	RoHS non-compliant
1N5817-T	Diodes Incorporated	20 V	1000	450 mV @ 1 A	Fast Recovery ≤ 500 ns, > 200 mA	DO-41	Active	ROHS3 Compliant
1N6857-1	Microchip Technology	20 V	150	750 mV @ 35 mA	Small Signal ≤ 200 mA, Any Speed	DO-35	Active	RoHS non-compliant
BAT85,113	Nexperia USA Inc.	30 V	200	800 mV @ 100 mA	Small Signal ≤ 200 mA, Any Speed	DO-34	Active	ROHS3 Compliant
BAT85,133	Nexperia USA Inc.	30 V	200	800 mV @ 100 mA	Small Signal ≤ 200 mA, Any Speed	DO-34	Active	ROHS3 Compliant
DSB0.2A20	Microchip Technology	20 V	200	500 mV @ 200 mA	Small Signal ≤ 200 mA, Any Speed	DO-35	Active	RoHS non-compliant
DSB0.2A40	Microchip Technology	20 V	200	510 mV @ 200 mA	Small Signal ≤ 200 mA, Any Speed	DO-35	Active	RoHS non-compliant
DSB0.5A20	Microchip Technology	20 V	500	650 mV @ 500 mA	Fast Recovery ≤ 500 ns, > 200 mA	DO-35	Active	RoHS non-compliant
DSB2810	Microchip Technology	20 V	75	410 mV @ 1 mA	Small Signal ≤ 200 mA, Any Speed	DO-35	Active	RoHS non-compliant

Engineering Selection Recommendations

For Direct Replacement with Identical Electrical Performance:

The DSB0.5A20 (Microchip Technology) provides the closest electrical match to the BAT47. It maintains the 20 V reverse voltage specification, exceeds the 350 mA current requirement with 500 mA capacity, and shares the fast recovery switching classification (≤ 500 ns, > 200 mA). The part is housed in the same DO-35 package and is currently in active production status with 1,047 units in stock. However, this part carries RoHS non-compliant status, whereas the BAT47 is ROHS3 compliant.

The 1N5817-T (Diodes Incorporated) offers superior current handling at 1 A with matching 20 V reverse voltage and fast recovery characteristics. This part is ROHS3 compliant and in active production. The package differs (DO-41 versus DO-35), requiring PCB layout modification. This option is suitable for applications where increased current margin and regulatory compliance are prioritized over form factor preservation.

For Reduced Current Applications:

The 1N6857-1 (Microchip Technology) operates at 150 mA, suitable for circuits where actual current demand is below 350 mA. It maintains 20 V reverse voltage and DO-35 packaging. The 1N5712 and 1N5712-1 (Microchip Technology) operate at 75 mA with identical voltage and package specifications. These parts are in active production but carry RoHS non-compliant status.

For Elevated Voltage Margin Applications:

The BAT85,113 and BAT85,133 (Nexperia USA Inc.) both provide 30 V reverse voltage rating with 200 mA current capacity. Both are ROHS3 compliant and in active production. The package is DO-34 (slightly different from DO-35), and both parts are available in high inventory quantities (22,058 and 26,781 units respectively).

Compliance Considerations:

Parts with ROHS3 compliance status include the BAT47 (original), 1N5817-T, BAT85,113, and BAT85,133. Parts with RoHS non-compliant status include 1N5712, 1N5712-1, 1N6857-1, DSB0.2A20, DSB0.2A40, DSB0.5A20, and DSB2810. Selection should account for end-product regulatory requirements and supply chain compliance mandates.

Frequently Asked Questions (FAQ)

Q: Can the 1N5712 directly replace the BAT47 in my circuit?

A: The 1N5712 shares the 20 V reverse voltage specification and DO-35 package with the BAT47. However, it is rated for only 75 mA average rectified current compared to the BAT47's 350 mA. Direct substitution is only valid if your circuit's actual current demand does not exceed 75 mA. Exceeding this rating will cause component failure.

Q: What is the difference between the 1N5712 and 1N5712-1?

A: Both parts are manufactured by Microchip Technology and share identical electrical specifications: 20 V reverse voltage, 75 mA current rating, and DO-35 packaging. The "-1" suffix typically indicates a variant designation. Both are in active production status and carry RoHS non-compliant status. Selection between them depends on supplier availability and internal part numbering systems.

Q: Why does the DSB0.5A20 have a higher forward voltage drop than the BAT47?

A: The DSB0.5A20 exhibits a forward voltage drop of 650 mV at 500 mA, compared to the BAT47's 1 V at 300 mA. Forward voltage characteristics vary with current density and semiconductor junction design. The DSB0.5A20's lower Vf at its rated current reflects its design optimization for higher current operation. At the BAT47's original 300 mA operating point, the DSB0.5A20 would exhibit a lower voltage drop than specified.

Q: Can I use the 1N5817-T as a substitute if my PCB is designed for DO-35 packages?

A: The 1N5817-T is housed in a DO-41 package, which has different physical dimensions and lead spacing than the DO-35 package. Direct PCB substitution without layout modification is not possible. However, the part can be used with manual rework, adapter boards, or PCB redesign. The 1N5817-T offers superior electrical performance (1 A current rating, ROHS3 compliance) if layout modification is feasible.

Q: Are the BAT85,113 and BAT85,133 interchangeable?

A: Yes. Both parts are manufactured by Nexperia USA Inc. and share identical electrical specifications: 30 V reverse voltage, 200 mA current rating, 800 mV forward voltage drop at 100 mA, and DO-34 packaging. Both are ROHS3 compliant and in active production. The different part number suffixes reflect internal Nexperia designation variants. Selection between them depends on supplier availability.

Q: What does "Small Signal ≤ 200 mA (Io), Any Speed" mean for the 1N5712?

A: This classification indicates that the 1N5712 is optimized for small-signal applications with current levels not exceeding 200 mA. The "Any Speed" designation means the part does not have a defined fast recovery switching specification. In contrast, the BAT47 is classified as "Fast Recovery ≤ 500 ns, > 200 mA (Io)," indicating optimized performance for high-frequency switching at currents above 200 mA. For high-frequency rectification applications, the BAT47's fast recovery characteristic is superior.

Q: Why is the BAT47 listed as obsolete if inventory is available?

A: Obsolete status indicates that the manufacturer (STMicroelectronics) has discontinued production and will not accept new orders. The 16,900 units in current stock represent remaining inventory from the final production run. Once this stock is depleted, the part will no longer be available. Identifying and qualifying substitute parts ensures design continuity and supply chain resilience.

Q: Can I use multiple lower-current parts in parallel to replace the BAT47?

A: Parallel connection of Schottky diodes is not recommended without careful analysis of current sharing characteristics. Schottky diodes exhibit positive temperature coefficients in their forward voltage characteristics, which can lead to unequal current distribution and thermal runaway in parallel configurations. Consult detailed application notes and thermal analysis before implementing parallel diode strategies.

Q: What is the significance of the reverse leakage current specification?

A: Reverse leakage current (Ir) represents the small current that flows through the diode when reverse-biased. The BAT47 specifies 10 µA at 20 V, while the 1N5712 specifies 150 nA at 16 V. Lower leakage current is generally preferable in precision analog circuits, high-impedance applications, and low-power designs. Higher leakage current may be acceptable in power rectification applications where leakage represents a negligible fraction of total circuit current.

Q: Does package size affect electrical performance?

A: Package size (DO-35 versus DO-34 versus DO-41) primarily affects thermal dissipation capability and physical form factor. Electrically, the semiconductor junction characteristics determine performance. However, larger packages generally provide better heat dissipation, which can improve reliability in high-current or high-frequency applications. The 1N5817-T's DO-41 package provides superior thermal performance compared to the BAT47's DO-35 package, making it suitable for higher current applications.

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