Hi,
As the subject says what is the purpose of the 10k resistor R2 on the due? It didn't make any sense to me unless it is a requirement for usb.
Thanks
Hi,
As the subject says what is the purpose of the 10k resistor R2 on the due? It didn't make any sense to me unless it is a requirement for usb.
Thanks
It discharges the decoupling capacitors when power is removed (probably so that the chip will reset reliably if
power is reapplied soon after). Nothing to do with USB I think.
Normally CMOS chips will not completely drain their supply capacitors when power is removed - in particular
when the xtal oscillator stops the power drain will become very low. The reset / brown out detection circuitry
may be fussy about how power rail(s) come back up on power up (ie assume they all start at 0V).
Its good practice (esp with higher voltages) to arrange large capacitors discharge when power is removed
so that they are not "live" during transport and storage - not exactly an issue at 5V, but it is something as
a circuit designer you would do as a matter of course.
Thanks for your response, I don't know why I didn't think of that. That makes perfect sense.