Power supply ?

[Alex Leech]

If i am powering the picaxe board through USB power would it be worth adding in a diode and capacitor to eliminate any backflow of power surges ??

Cheers


Alex

 

[Alex Leech]

Bear in mind:

Supplied voltage by a host or a powered hub ports is between 4.75 V and 5.25 V. Maximum voltage drop for bus-powered hubs is 0.35 V from its host or hub to the hubs output port. All hubs and functions must be able to send configuration data at 4.4 V, but only low-power functions need to be working at this voltage. Normal operational voltage for functions is minimum 4.75 V.

Alex

 

[hippy]

Probably worthwhile if there is a possibility of injecting current into the USB supply, such as when local voltage is higher than USB supply voltage. Note that any capacitor will have an in-rush current and this could exceed the USB specifications, shut down or damage a USB port.

It would be recommended to follow all aspects of USB specifications when drawing power from the USB supply, and this will require fully understanding the relevant parts of those USB specifications.

There have been other discussions on drawing power from USB ports on the forum so well worth searching them out.

 

[Alex Leech]

Ah i see!

My circuit is only drawing a max of 10mA so its fine to use with USB.

I shall add a diode and thats all.

Thanks all !!

Alex