Schottdy diode or rectifier for reverse protection? - Page 1
Forum section: electronics / beginners

author: level6
author_rank: Regular Contributor
timestamp: January 31, 2020, 09:56:37 pm
content: I need to add reverse current protection to my project and plan to add Schottky diodes/rectifier parts to do this.Is there any difference between a Schottky diode and rectifier? I'm reading that rectifiers are for converting AC to DC and diodes for blocking reverse voltage, yet most of the examples I have found for reverse protection use Schottky rectifiers, not specifically diodes.Some products are described as Schottky diodes and some as Schottky rectifiers. Is there really a difference?

author: Wimberleytech
author_rank: Super Contributor
timestamp: January 31, 2020, 10:18:20 pm
content: Quote from: level6 on January 31, 2020, 09:56:37 pmOK, the IEEE dictionary sez!Rectifier circuit element: A circuit element bounded by two circuit terminals that has the characteristic of conducting current substantially in one direction only. Note: The rectifier circuit element may consist of more than one semiconductor rectifier cell, rectifier diode, or rectifier stack connected in series or parallel or both, to operate as a unit.So, rectifiers consist of one or more diodes. The diodes can be semiconductor junction diodes or Schottky barrier diodes. Sometimes a product advertised as a Schottky rectifier contains two Schottky diodes and three terminals.EEs are not known for consistency and precise language.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 31, 2020, 10:18:52 pm
content: Diodes are used to rectifire, so TS question has no sence.

author: WattsThat
author_rank: Frequent Contributor
timestamp: January 31, 2020, 10:42:22 pm
content: Schottky diodes are sometimes used in the application instead of standard silicon rectifiers due to their lower forward voltage drop, 0.2-0.3 volts for Schottky verses 0.7 for standard 1N400x rectifiers.

author: GerryR
author_rank: Frequent Contributor
timestamp: January 31, 2020, 11:57:48 pm
content: I believe the Schottky "rectifier" would be used in a higher current application versus the Schottky diode which would be used in a signal diode application. The rectifier version would have a slightly higher forward voltage drop, due to physical construction, but not significantly higher, and still lower than conventional silicon diodes and rectifiers. Both are much faster in switching applications than the standard diodes, both in the forward and reverse directions. JM $.02

author: gbaddeley
author_rank: Regular Contributor
timestamp: February 01, 2020, 12:44:29 am
content: Rectifiers are actually diodes, but with ratings and packaging (multiple diodes) that make them suitable for rectifying applications.For reverse voltage protection on output of a power supply, schottky are good because they conduct at a much lower voltage than silicon, so are more likely to protect the rest of the circuit. However, the max required current limit needs to be considered, so the diode won’t blow. What external device could be connected in reverse, and how much current could it source? 1A 10A 100A?

author: level6
author_rank: Regular Contributor
timestamp: February 01, 2020, 01:10:06 am
content: Quote from: gbaddeley on February 01, 2020, 12:44:29 amI plan to use the Schottky to protect a device from having it's power supply plugged in reverse. It's for input protection. The rectifier I'm looking at, STPS1L60, has a forward current of 1A and the device draws at max about 28ma.

author: mariush
author_rank: Super Contributor
timestamp: February 01, 2020, 01:30:01 am
content: You should look into a p channel mosfet to do reverse voltage protectionif you're only dealing with low voltages the zener diode could be missing, i think. and with such low currents cheap tiny mosfets would be doable.See also appnote showing 3 reverse voltage protection circuits and explaining them:https://www.infineon.com/dgdl/Reverse-Batery-Protection-Rev2.pdfThis is also informative:https://www.maximintegrated.com/en/design/technical-documents/app-notes/6/636.html

author: Vovk_Z
author_rank: Super Contributor
timestamp: February 01, 2020, 09:10:45 am
content: Quote from: mariush on February 01, 2020, 01:30:01 amIf every mV drop matters then yes. But he say 28 mA load current so simple 1A rated Shottky diode will have 0.2..0.3 V voltage drop.

author: level6
author_rank: Regular Contributor
timestamp: February 01, 2020, 04:51:29 pm
content: Quote from: Vovk_Z on February 01, 2020, 09:10:45 amYeah, adding a MOSFET would be a bit overkill. I've tested my circuit with a Schottky in the SOT-123 package and it's working fine, plenty of voltage left over to run the circuit.