topic Re: Power supply config in Vybrid Processors

Power supply config

keisukewatanabe — Thu, 04 Jul 2013 01:35:19 GMT

Limitation is not listed in a datasheet, is the constitution of power supply such as follows possible?

Case1 VDD=1.2V OFF VDD33=3.3V OFF SDRAMC_VDD1P5=1.5V ON

Case 2 VDD=1.2V ON VDD33=3.3V ON SDRAMC_VDD1P5=1.5V OFF

Re: Power supply config

naoumgitnik — Fri, 05 Jul 2013 20:42:45 GMT

Dear Keisuke,

VDD33=3.3V is applied to Vybrid first in the power-up sequence.
VDD=1.2V is generated by Vybrid itself, without any user's intervention.
SDRAMC_VDD1P5=1.5V - is applied to Vybrid with arbitrary timing with respect to the above rails.
Regarding the mutual timing of the 3.3V rail and the transistor collector voltage (if different than VDD33) – to not overload the BCTRL output pin, the transistor collector voltage should appear no later than 3.3V.

Sincerely yours, Naoum Gitnik.

Re: Power supply config

keisukewatanabe — Tue, 09 Jul 2013 06:19:04 GMT

Dear Naoum,

Thank you for your reply.

I think that case1 does not have any problem from your answer.

Does case2 not have any problem?

Best regards,

Keisuke Watanabe

Re: Power supply config

naoumgitnik — Tue, 09 Jul 2013 19:13:48 GMT

Dear Keisuke,

Case 2 cannot happen - 1.2V is generated from 3.3V (see attachment).

Sincerely yours, Naoum Gitnik.

Re: Power supply config

keisukewatanabe — Thu, 11 Jul 2013 01:08:28 GMT

Dear Naoum,

I mistake, case1 and case2 was the reverse.

Does case1 not have any problem?

Best regards,

Keisuke Watanabe

Re: Power supply config

keisukewatanabe — Thu, 11 Jul 2013 02:16:14 GMT

Dear Naoum,

In figure 4.Power supply, "SDRAMC_VDD1P5" seems to be provided from external power supply.

Therefore I think the case2 can happen.

Please correct me if I am missing some point.

Best regards,

Keisuke Watanabe

Re: Power supply config

naoumgitnik — Fri, 12 Jul 2013 18:30:58 GMT

Dear Keisuke,

Regarding "Case1: VDD=1.2V OFF, VDD33=3.3V OFF, SDRAMC_VDD1P5=1.5V ON".

No problem with Case1 because the SDRAMC_VDD1P5 power rail order is NA (Not Applicable = Do not care = Arbitrary) in the sequence table.

Best regards, Naoum.

Re: Power supply config

naoumgitnik — Fri, 12 Jul 2013 18:38:17 GMT

Dear Keisuke,

Regarding "Case 2: VDD=1.2V ON, VDD33=3.3V ON, SDRAMC_VDD1P5=1.5V OFF".

Yes, the case when SDRAMC_VDD1P5 is not applied (but VDD and VDD33 are) is possible.

I replied "impossible" and sent the scope screenshots because I thought you also meant the sequence:

first VDD=1.2V is applied,
second VDD33=3.3V is applied,
third SDRAMC_VDD1P5=1.5V is applied.

That is why I replied "1.2V is generated from 3.3V".

If you only meant their presence, without sequence, then this case is indeed possible.

Best regards, Naoum.

Re: Power supply config

keisukewatanabe — Tue, 16 Jul 2013 05:14:43 GMT

Dear Naoum,

Thank you for your reply.

Even a state of regular case1 (or case2) does not have any problem.

Is it right by the interpretation mentioned above ?

Best regards,

Keisuke Watanabe

Re: Power supply config

naoumgitnik — Tue, 16 Jul 2013 14:42:37 GMT

Dear Keisuke,

Yes, it is right.

Best regards, Naoum.