Equivalent & Substitute Parts for 20TQ035 Schottky Diode

Part Overview

The Vishay 20TQ035 is a Schottky rectifier diode rated for 35 V reverse voltage and 20 A average rectified current in a TO-220AC package. This component is classified as obsolete, which necessitates identification of equivalent and substitute parts for ongoing design support and procurement. The 20TQ035 operates across a junction temperature range of -55°C to 150°C and exhibits fast recovery characteristics suitable for high-frequency switching applications.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	35	V
Current - Average Rectified (Io)	20	A
Voltage - Forward (Vf) (Max) @ If	570 mV @ 20 A	mV
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	2.7	mA @ 35 V
Capacitance @ Vr, F	1400	pF @ 5V, 1MHz
Mounting Type	Through Hole	—
Package / Case	TO-220-2	—
Operating Temperature - Junction	-55 to 150	°C
Technology	Schottky	—

Substitute Part Grouping Explanation

Substitution of the 20TQ035 is determined by the following critical parameters:

Primary Substitution Criteria:

Voltage - DC Reverse (Vr) rating must equal or exceed 35 V
Current - Average Rectified (Io) must equal or exceed 20 A
Package / Case must be TO-220-2 or compatible TO-220AC
Mounting Type must be Through Hole
Technology must be Schottky
Speed must be Fast Recovery ≤ 500ns, > 200mA (Io)

Substitution Categories:

Parametric Equivalent: Parts with identical electrical specifications and package configuration. The VS-20TQ035THN3 from Vishay meets all electrical parameters and maintains the same package footprint, with the distinction of active product status and RoHS3 compliance.

Manufacturer Recommended Substitute: Parts with equal or superior electrical ratings that maintain functional compatibility. The DSS25-0045A (IXYS) and MBR1635G (onsemi) provide alternative solutions with different performance trade-offs in voltage, current, and thermal characteristics.

Parameter Comparison

Parameter	20TQ035 (Main)	VS-20TQ035THN3 (Parametric Equivalent)	DSS25-0045A (MFR Recommended)	MBR1635G (MFR Recommended)
Manufacturer	Vishay General Semiconductor	Vishay General Semiconductor	IXYS	onsemi
Voltage - DC Reverse (Vr) (Max)	35 V	35 V	45 V	35 V
Current - Average Rectified (Io)	20 A	20 A	25 A	16 A
Voltage - Forward (Vf) (Max) @ If	570 mV @ 20 A	570 mV @ 20 A	690 mV @ 25 A	630 mV @ 16 A
Speed	Fast Recovery ≤ 500ns, > 200mA (Io)	Fast Recovery ≤ 500ns, > 200mA (Io)	Fast Recovery ≤ 500ns, > 200mA (Io)	Fast Recovery ≤ 500ns, > 200mA (Io)
Current - Reverse Leakage @ Vr	2.7 mA @ 35 V	2.7 mA @ 35 V	1 mA @ 45 V	200 µA @ 35 V
Package / Case	TO-220-2	TO-220-2	TO-220-2	TO-220-2
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Operating Temperature - Junction	-55 to 150°C	-55 to 150°C	-55 to 175°C	-65 to 175°C
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	RoHS3 Compliant	RoHS3 Compliant	RoHS3 Compliant

Engineering Selection Recommendations

VS-20TQ035THN3 (Vishay General Semiconductor - Diodes Division)

The VS-20TQ035THN3 is the direct parametric equivalent to the 20TQ035. This part maintains identical electrical specifications including 35 V reverse voltage, 20 A average rectified current, 570 mV forward voltage drop at 20 A, and 1400 pF capacitance. The VS-20TQ035THN3 is classified as an active product with RoHS3 compliance, addressing the obsolescence status of the original 20TQ035. This part is the preferred selection for direct replacement in existing designs where electrical performance and thermal characteristics must remain unchanged.

DSS25-0045A (IXYS)

The DSS25-0045A provides a manufacturer-recommended substitute with enhanced voltage and current ratings (45 V, 25 A). This part is suitable for applications requiring higher voltage margin or increased current capacity. The forward voltage drop increases to 690 mV at 25 A, and reverse leakage improves to 1 mA at 45 V. Operating temperature range extends to 175°C. This part is RoHS3 compliant and active. Selection of this part is appropriate when design specifications permit the higher voltage and current ratings.

MBR1635G (onsemi SWITCHMODE™ Series)

The MBR1635G is a manufacturer-recommended substitute with 35 V reverse voltage matching the original specification, but with reduced current rating of 16 A. This part exhibits superior reverse leakage characteristics (200 µA at 35 V) and extended operating temperature range (-65 to 175°C). The forward voltage drop is 630 mV at 16 A. This part is RoHS3 compliant and active. Selection of this part is appropriate for applications where the 16 A current rating is sufficient and improved leakage performance is beneficial.

Frequently Asked Questions (FAQ)

Q: Can the VS-20TQ035THN3 be used as a direct replacement for the 20TQ035?

A: Yes. The VS-20TQ035THN3 is a parametric equivalent with identical electrical specifications (35 V, 20 A, 570 mV forward voltage, 1400 pF capacitance) and the same TO-220-2 package. The primary difference is product status (active versus obsolete) and RoHS3 compliance. No circuit modifications are required.

Q: What is the difference between the DSS25-0045A and the original 20TQ035?

A: The DSS25-0045A has higher voltage (45 V versus 35 V) and current (25 A versus 20 A) ratings. Forward voltage drop increases to 690 mV at 25 A, and reverse leakage improves to 1 mA. Operating temperature range extends to 175°C. The part is suitable for applications requiring higher ratings or improved thermal performance.

Q: Why does the MBR1635G have a lower current rating than the 20TQ035?

A: The MBR1635G is rated for 16 A average rectified current, which is lower than the 20TQ035 specification of 20 A. This part is suitable only for applications where the 16 A rating is sufficient. The advantage of this part is superior reverse leakage performance (200 µA versus 2.7 mA) and extended operating temperature range.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. The VS-20TQ035THN3, DSS25-0045A, and MBR1635G are all RoHS3 compliant. The original 20TQ035 is RoHS non-compliant. Selection of any substitute part addresses RoHS compliance requirements.

Q: Do all substitute parts use the same TO-220-2 package?

A: Yes. All substitute parts (VS-20TQ035THN3, DSS25-0045A, and MBR1635G) use the TO-220-2 package with through-hole mounting. PCB footprint compatibility is maintained across all options.

Q: What is the primary criterion for selecting between the three substitute options?

A: Selection depends on application requirements. For identical electrical performance and direct replacement, select VS-20TQ035THN3. For higher voltage and current margins, select DSS25-0045A. For improved reverse leakage and extended temperature range with reduced current capacity, select MBR1635G. All three parts maintain fast recovery characteristics and Schottky technology.

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