LPC4330 RTC Pins

[murdomcleod]

Hi,

What should I do with the unused LPC4330 RTC pins in my design(VBAT, RTCX1, and RTCX2)?

Should I pull them low, high, or what should I connect them to?

Many thanks,

Murdo.

[soledad]

Hi,

When the RTC is not used, connect VBAT to VDD(REG)(3V3), I would recommend that RTCX1 be grounded since it is an input.  RTCX2 is an output, so it can be left open.

Have a great day,
Sol

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[murdomcleod]

Hello Sol,

Thank you for replying so quickly.

In the question and response at https://community.nxp.com/thread/420015 Paul said that connecting VBAT is not required as the RTC is powered by either VDD(REG) or VBAT. I am finding it hard to route the VBAT under the already routed 256-pin BGA, so I am keen to know if it does require 3V3 or if I could leave it floating?

In the datasheet at https://www.nxp.com/docs/en/data-sheet/LPC4350_30_20_10.pdf (page 83, fig 9) it shows the two power rails just diode-Or'd so I wonder if VBAT needs any connection at all.

Kind regards,

Murdo.

[soledad]

Hi,

I strongly suggest that you connect the VBAT to Vdd to avoid current Leakage.

Have a great day,
Sol

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