Equivalent & Substitute Parts for 20TQ045 Schottky Diode

Part Overview

The Vishay 20TQ045 is a 45V, 20A Schottky rectifier diode in TO-220AC package designed for through-hole mounting applications. This part is classified as obsolete, making equivalent and substitute components necessary for ongoing design support and procurement. The 20TQ045 operates across a junction temperature range of -55°C to 150°C and exhibits fast recovery characteristics suitable for high-frequency rectification circuits. Identification of compatible alternatives ensures design continuity and supply chain flexibility.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) Maximum	45	V
Current - Average Rectified (Io)	20	A
Voltage - Forward (Vf) Maximum @ If	570 mV @ 20 A	mV
Speed Classification	Fast Recovery ≤ 500ns, > 200mA (Io)	ns
Current - Reverse Leakage @ Vr	2.7	mA @ 45 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 20TQ045 is determined by the following critical parameters:

Primary Substitution Criteria:

Voltage rating (Vr) must equal or exceed 45V
Current rating (Io) must meet or exceed 20A for direct replacement
Package type must be TO-220-2 or TO-220AC (through-hole compatible)
Technology must be Schottky for fast recovery characteristics
Operating temperature range must support the application requirements

Substitution Categories:

Direct Parametric Equivalent: Parts matching all electrical specifications and current rating (20A minimum) with identical package footprint.

Manufacturer Recommended Substitute: Parts with equal or superior voltage and current ratings, same package type, and active product status. These may exhibit different forward voltage or leakage characteristics within acceptable engineering tolerances.

Compatible Alternatives: Parts meeting voltage and package requirements with current ratings below the original specification (16A) or above (25A), suitable for applications where the exact 20A rating is not critical.

Parameter Comparison

Parameter	20TQ045 (Vishay)	VS-20TQ045THN3 (Vishay)	DSS25-0045A (IXYS)	MBR1645-BP (Micro Commercial)	MBR1645G (onsemi)
Voltage - DC Reverse (Vr) Max	45 V	45 V	45 V	45 V	45 V
Current - Average Rectified (Io)	20 A	20 A	25 A	16 A	16 A
Voltage - Forward (Vf) Max @ If	570 mV @ 20 A	570 mV @ 20 A	690 mV @ 25 A	Not Specified	630 mV @ 16 A
Speed	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA	Fast Recovery ≤ 500ns, > 200mA
Current - Reverse Leakage @ Vr	2.7 mA @ 45 V	2.7 mA @ 45 V	1 mA @ 45 V	200 µA @ 45 V	200 µA @ 45 V
Capacitance @ Vr, F	1400 pF @ 5V, 1MHz	1400 pF @ 5V, 1MHz	Not Specified	450 pF @ 4V, 1MHz	Not Specified
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-220-2	TO-220-2	TO-220-2	TO-220-2	TO-220-2
Operating Temperature - Junction	-55 to 150°C	-55 to 150°C	-55 to 175°C	-55 to 150°C	-65 to 175°C
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	Not Specified	ROHS3 Compliant

Engineering Selection Recommendations

VS-20TQ045THN3 (Vishay General Semiconductor - Diodes Division)

This part is the direct parametric equivalent to the 20TQ045. It maintains identical electrical specifications including 45V reverse voltage, 20A average rectified current, 570 mV forward voltage at 20A, and 1400 pF capacitance. The VS-20TQ045THN3 is manufactured by the same supplier as the original part and carries active product status with ROHS3 compliance. This substitute is recommended as the primary replacement for direct circuit compatibility without design modification.

DSS25-0045A (IXYS)

This IXYS component provides a higher current rating of 25A while maintaining the 45V voltage specification and TO-220-2 package. The DSS25-0045A exhibits lower reverse leakage current (1 mA versus 2.7 mA) and supports an extended operating temperature range to 175°C. Forward voltage is specified at 690 mV for 25A operation. This part is suitable for applications requiring enhanced current capacity or extended temperature performance. ROHS3 compliance is confirmed.

MBR1645G (onsemi SWITCHMODE™ Series)

The MBR1645G is rated for 16A at 45V in TO-220-2 package with active product status and ROHS3 compliance. This part exhibits lower reverse leakage (200 µA) and supports an extended temperature range to 175°C. The forward voltage is specified at 630 mV for 16A operation. The MBR1645G is suitable for applications where the 20A rating of the original part exceeds circuit requirements. High inventory availability (17,020 units) supports procurement flexibility.

MBR1645-BP (Micro Commercial Co)

This Micro Commercial component provides 16A at 45V in TO-220-2 package with active product status. The MBR1645-BP exhibits significantly lower reverse leakage (200 µA) and reduced capacitance (450 pF) compared to the original 20TQ045. Operating temperature range is -55°C to 150°C, matching the original part. This substitute is applicable for designs where 16A current capacity is sufficient and lower leakage characteristics are beneficial.

Frequently Asked Questions (FAQ)

Q: Can the VS-20TQ045THN3 be used as a direct replacement for the 20TQ045?

A: Yes. The VS-20TQ045THN3 is a direct parametric equivalent with identical voltage (45V), current (20A), forward voltage (570 mV @ 20A), and capacitance (1400 pF) specifications. Both parts use TO-220-2 package and Schottky technology. The primary difference is product status: VS-20TQ045THN3 is active and ROHS3 compliant, whereas the original 20TQ045 is obsolete and non-compliant.

Q: What is the difference between the 20A-rated 20TQ045 and the 16A-rated MBR1645G?

A: The MBR1645G is rated for 16A average rectified current compared to the 20TQ045's 20A rating. Both maintain 45V reverse voltage and TO-220-2 package compatibility. The MBR1645G exhibits lower reverse leakage current (200 µA versus 2.7 mA) and supports a higher maximum junction temperature (175°C versus 150°C). Selection depends on circuit current requirements: use MBR1645G only if the application draws 16A or less.

Q: Why does the DSS25-0045A have a higher forward voltage (690 mV @ 25A) than the 20TQ045 (570 mV @ 20A)?

A: Forward voltage specifications are measured at their respective rated currents. The DSS25-0045A is rated for 25A operation, while the 20TQ045 is rated for 20A. Forward voltage increases with current in Schottky diodes. Direct voltage comparison requires measurement at identical current levels, which are not provided for all parts in this dataset.

Q: Are all substitute parts available in the same TO-220-2 package?

A: Yes. All substitute parts listed (VS-20TQ045THN3, DSS25-0045A, MBR1645-BP, and MBR1645G) use TO-220-2 package with through-hole mounting. This ensures mechanical and thermal compatibility with the original 20TQ045 footprint without PCB redesign.

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

A: The DSS25-0045A exhibits the lowest reverse leakage at 1 mA @ 45V, followed by MBR1645-BP and MBR1645G at 200 µA @ 45V. The original 20TQ045 and VS-20TQ045THN3 both specify 2.7 mA @ 45V. Lower leakage current reduces standby power consumption in applications with sustained reverse bias conditions.

Q: Can I use a 16A-rated diode in a circuit designed for 20A?

A: No. Using a 16A-rated diode (MBR1645-BP or MBR1645G) in a circuit requiring 20A operation exceeds the component's current rating and creates reliability risk. Current rating represents the maximum average rectified current the diode can safely conduct. Exceeding this rating causes excessive junction heating and accelerated failure. Select a substitute with current rating equal to or greater than the circuit requirement.

Q: What is the significance of ROHS3 compliance for these diodes?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, and other hazardous materials. The original 20TQ045 is non-compliant. All active substitute parts (VS-20TQ045THN3, DSS25-0045A, MBR1645G) are ROHS3 compliant, supporting regulatory requirements in many markets and applications.

Q: Which substitute offers the best thermal performance?

A: The DSS25-0045A and MBR1645G both support maximum junction temperatures of 175°C, compared to 150°C for the original 20TQ045 and MBR1645-BP. Extended temperature rating provides thermal margin in high-ambient or high-power applications. The DSS25-0045A additionally offers 25A current capacity for enhanced thermal distribution in high-current circuits.

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