I found a neat little component USBUF02W6 which is basically a bunch of resistors, capacitors, and diodes, built into one package. All you need is provide a 3.3V signal to it.
http://ca.mouser.com/search/ProductDeta ... udxXreiQ==
This one component should in theory replace all of the 68 ohm resistors, zener diodes, and the pull-up resistor that most V-USB based circuits currently use. Am I correct?
neat part: USBUF02W6 USB buffer
Re: neat part: USBUF02W6 USB buffer
_frank26080115 wrote:All you need is provide a 3.3V signal to it.
Certainly looks interesting but doesn't it also require a 3.3V supply? If so then we still need to use a LDO regulator or series diode voltage drop. However, given all the added bonuses like EMI & ESD protection it is probably well worth considering for any commercial app.
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_frank26080115
Re: neat part: USBUF02W6 USB buffer
maxi wrote:_frank26080115 wrote:All you need is provide a 3.3V signal to it.
Certainly looks interesting but doesn't it also require a 3.3V supply? If so then we still need to use a LDO regulator or series diode voltage drop. However, given all the added bonuses like EMI & ESD protection it is probably well worth considering for any commercial app.
Ah yes I think I meant to say supply
Re: neat part: USBUF02W6 USB buffer
_frank26080115 wrote:Ah yes I think I meant to say supply
Unfortunately, a 3.3V supply rules out a good number of AVR8s for F_CPU
After looking over the datasheet linked in your OP, I have been wondering if the following setup might work:
Operate the MCU from the 5V from the USB port and feed the 3.3V pin on the USBUF02W6 with a pair of GP diodes in series. The datasheet is lacking in information about in internal ZD's but it's a reasonably safe bet they will tolerate 5V and therefore act in very much the same way as the (wiki prescribed) ZD hardware approach.
This idea is untested ofcourse!