OMAP-L138 Power Sequence without using RTC

Joern Henneberg

Other Parts Discussed in Thread: OMAP-L138, OMAPL138

Hi,

we are running the OMAP-L138 at 456 MHz (CVDD=1.3V), but are not using RTC. We are using a 2% regulator for the 1.3V (that we'd like to keep), so we cannot tie RTC_CVDD to CVDD without exceeding the 1.32V max recommended operating condition for RTC_CVDD, and therefore keep it on a separate regulator.

For power sequencing, the Application Report slva371b states that RTC_CVDD can be included in the static 1.2V supply domain - see note (5):

Therefore, our sequencing would look like this:

Is this a valid sequence or is the Application Report outdated?

Thanks,

Joern

over 13 years ago

0 Mukul Bhatnagar over 13 years ago

TI__Guru* 83965 points

Joern

Since you are not using RTC in your design, it is ok to tie it with CVDD (1.35V max). The 1.32V max requirement is for the RTC VDD when it is being used/functional.

Hope this helps.

Regards

Mukul

0 j-breeze over 12 years ago in reply to Mukul Bhatnagar

Mastermind 7560 points

Hi Mukul

Is there any documentation related to the spec mentioned in your previous post below?

>
> not using RTC in your design, it is ok to tie it with CVDD (1.35V max)
>

Best regards,
j-breeze

0 Mukul Bhatnagar over 12 years ago in reply to j-breeze

TI__Guru* 83965 points

Hi J Breeze

It is perhaps not documented explicitly.

It is "implied" from Pg 83 in the OMAPL138 datasheet

RTC (RTC_CVDD) may be powered from an external device (such as a battery) prior to all other supplies being applied or powered-up at the same time as CVDD. If the RTC is not used, RTC_CVDD should be connected to CVDD. RTC_CVDD should not be left unpowered while CVDD is powered.

Regards

Mukul

0 j-breeze over 12 years ago in reply to Mukul Bhatnagar

Mastermind 7560 points

Hi Mukul

Thank you for your kind reply. I understood the description.

Best regards,
j-breeze

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OMAP-L138 Power Sequence without using RTC