EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: catalyst on September 25, 2018, 08:12:07 am
-
Hi,
I have designed a USB Charger for busses. We assume that a person may do a short circuit by using metal pen or tweezers etc. Because automotive a place that has very vandalism. I have to think anti-vandal solution for this. Because USB connectors are fragile to bad external factor. Do you have any suggestions for me? How can i protect USB connector by using a component or etc. For example, a diode may be acceptable but, diode's threshold voltage will decrease my USB voltage(5V) and this effect will affect my charge performance.
Thank you for answering.
-
Hi,
I have designed a USB Charger for busses. We assume that a person may do a short circuit by using metal pen or tweezers etc. Because automotive a place that has very vandalism. I have to think anti-vandal solution for this. Because USB connectors are fragile to bad external factor. Do you have any suggestions for me? How can i protect USB connector by using a component or etc. For example, a diode may be acceptable but, diode's threshold voltage will decrease my USB voltage(5V) and this effect will affect my charge performance.
Thank you for answering.
Maybe you could use a diode between the rails and have a 1K resistor on 5V and neutral to keep current from flowing that way under reverse conditions? Though if you want to do it nicely, it'd probably be a good idea to use a transistor. That way you'll barely have a voltage drop.
http://www.electroboom.com/?tag=reverse-polarity (http://www.electroboom.com/?tag=reverse-polarity)
-
One of those power switches from Micrel. (Microchip)
MIC2505 (http://ww1.microchip.com/downloads/en/DeviceDoc/20005579A.pdf) for example.
-
Hello, I solve the problem which is related to reverse connection. Now, I face a short circuit problem at the output of USB connectors. For example, If someone touches a conductive material between +5V and GND pins, TS30042 explodes unfortunately. I have a solution, use a fuse. But if I use a fuse at 5V, its voltage dropout decrease the 5V to 4.9V. This can be a problem for charging. What can I do for this problem?
Thank you for answering.
-
Hi,
I would suggest using a polyFuse. There are models especially for 5V usb and chargers
Fox example take a look at this low resistance ones: http://m.littelfuse.com/products/resettable-ptcs/low-resistance.aspx (http://m.littelfuse.com/products/resettable-ptcs/low-resistance.aspx)
-
Raise the output voltage to 5.2V, like all typical USB chargers. The fuse, connector and cable add voltage drop.