Apr 15, 2010 #1 L LOLsim Junior Member level 3 Joined Dec 19, 2008 Messages 29 Helped 0 Reputation 0 Reaction score 0 Trophy points 1,281 Activity points 1,502 I have a 7805 circuit, can I connect it directly to a USB port to power off some USB devices that might take up to 500mA? There is no proper current limitation as the 7805 can provide more than 1A. The power source for the 7805 is a 12V Lead acid battery. There is also a 1.45A fuse for protection of my other circuit.
I have a 7805 circuit, can I connect it directly to a USB port to power off some USB devices that might take up to 500mA? There is no proper current limitation as the 7805 can provide more than 1A. The power source for the 7805 is a 12V Lead acid battery. There is also a 1.45A fuse for protection of my other circuit.
Apr 16, 2010 #2 cameo_2007 Advanced Member level 3 Joined Mar 15, 2007 Messages 748 Helped 70 Reputation 142 Reaction score 44 Trophy points 1,308 Location 12°58' N77°38'E Activity points 5,023 LOLsim said: I have a 7805 circuit, can I connect it directly to a USB port to power off some USB devices that might take up to 500mA? Click to expand... there should not be absolutely any problem in using it. There is no proper current limitation as the 7805 can provide more than 1A. Click to expand... that does not matter.It will provide only what the load asks for ,and that is 500mA. But make sure that you provide a heat sink for 7805. [/quote]
LOLsim said: I have a 7805 circuit, can I connect it directly to a USB port to power off some USB devices that might take up to 500mA? Click to expand... there should not be absolutely any problem in using it. There is no proper current limitation as the 7805 can provide more than 1A. Click to expand... that does not matter.It will provide only what the load asks for ,and that is 500mA. But make sure that you provide a heat sink for 7805. [/quote]
Apr 16, 2010 #3 L LOLsim Junior Member level 3 Joined Dec 19, 2008 Messages 29 Helped 0 Reputation 0 Reaction score 0 Trophy points 1,281 Activity points 1,502 OK, thanks. I'm worried about the current flow. Maybe I'll just put a 0.5A fuse to protect it from shorts.
OK, thanks. I'm worried about the current flow. Maybe I'll just put a 0.5A fuse to protect it from shorts.
Apr 16, 2010 #4 cameo_2007 Advanced Member level 3 Joined Mar 15, 2007 Messages 748 Helped 70 Reputation 142 Reaction score 44 Trophy points 1,308 Location 12°58' N77°38'E Activity points 5,023 you need not actually worry about the o/p current limiting of the regulator. If you look at the data sheet, It has inbuilt short circuit protection.It will tolerate the short.
you need not actually worry about the o/p current limiting of the regulator. If you look at the data sheet, It has inbuilt short circuit protection.It will tolerate the short.