LPC MicrocontrollersのトピックRe: unused RTC pins

unused RTC pins

lpcware — Wed, 15 Jun 2016 18:41:57 GMT

Content originally posted in LPCWare by inspire on Mon Nov 03 04:37:26 MST 2014
Hi,

the LPC4337 has an RTC which I don't need. Can I just connect leave the Vbat and RTCX1 pins floating or should I connect them to 3.3V/GND?

Thanks!

Re: unused RTC pins

lpcware — Wed, 15 Jun 2016 18:41:58 GMT

Content originally posted in LPCWare by NXP_Paul on Mon Nov 03 07:33:08 MST 2014
The data sheet and user's manual don't appear to specify this information, however, other LPC microcontrollers state that if the RTC is not used, these pins may be left floating.
I will verify, and request that this information be placed in the data sheet.

Regards
Paul

Re: unused RTC pins

lpcware — Wed, 15 Jun 2016 18:41:59 GMT

Content originally posted in LPCWare by inspire on Tue Nov 04 04:11:22 MST 2014
Hi Paul,

e.g. for the LPC1769 it says "When the RTC is not used, connect VBAT to VDD(REG)(3V3) and leave RTCX1 floating."

Please let me know what you found out!

Thanks!

Re: unused RTC pins

lpcware — Wed, 15 Jun 2016 18:42:00 GMT

Content originally posted in LPCWare by NXP_Paul on Wed Nov 05 07:39:10 MST 2014
The RTC is in an always-on power domain, powered either by VBAT or VDDREG, so connecting VBAT is not required. I would recommend that RTCX1 be grounded since it is an input. RTCX2 is an output, so it can be left open.

Paul

Re: unused RTC pins

lpcware — Wed, 15 Jun 2016 18:42:00 GMT

Content originally posted in LPCWare by inspire on Thu Nov 06 14:08:02 MST 2014
Alright, thanks! So RTCX1 has no internal pull up resistor?