Electronics > Beginners
Schottdy diode or rectifier for reverse protection?
gbaddeley:
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?
level6:
--- Quote from: gbaddeley on February 01, 2020, 12:44:29 am ---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?
--- End quote ---
I 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.
mariush:
You should look into a p channel mosfet to do reverse voltage protection
if 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.pdf
This is also informative: https://www.maximintegrated.com/en/design/technical-documents/app-notes/6/636.html
Vovk_Z:
--- Quote from: mariush on February 01, 2020, 01:30:01 am ---You should look into a p channel mosfet to do reverse voltage protection
--- End quote ---
If 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.
level6:
--- Quote from: Vovk_Z on February 01, 2020, 09:10:45 am ---
--- Quote from: mariush on February 01, 2020, 01:30:01 am ---You should look into a p channel mosfet to do reverse voltage protection
--- End quote ---
If 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.
--- End quote ---
Yeah, 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.
Navigation
[0] Message Index
[*] Previous page
Go to full version