-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Somebody in the thread at some point said: | Am So 20. April 2008 schrieb Werner Almesberger: |> Andy Green wrote: |>> I guess if we go this way we have to examine the 50633 defaults closely |>> to see what the other options are if any. |> STBYCTL1 and STBYCTL2 don't enable regulators in Standby mode. |> So we need some other way to get from NoPower into Standby, or |> give the MPU its own independent regulator. |> |> That's why being able to hook it up to battery/USB power would |> have been nice. But yes, we'd burn a bit of power. | | Hey no problem: we spend a FET (Vbat) and a Schottky diode (Vcore, whatever) | for the MPU itself, so it can switch off it's own Vbat as soon as there's a | better supply - like 1.8V from some converter, or maybe the backup bat | (probably use the one of PCF50633?) | | This way we burn the excessive power only during a few seconds on MPU-boot / | PMU setup.
Let's all continue to have a think for a bit. This is one of those issues that is mega dangerous and can easily lead to broken prototypes that don't boot. We didn't settle on NXP (at least I didn't hear Tony say anything) but I don't think we can burden the core design with new chips and so on to solve this. And I'm not sure about series diodes. Correct me if I am wrong, but doesn't VSYS see USB power, ie, 5V? We can't use that directly if so. There is a 1.8V in standby because the memory takes it, we can use that. ~ When we need 2.2V not sure what the story should be. - -Andy -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org iEYEARECAAYFAkgLjeIACgkQOjLpvpq7dMq99QCfXR9afkBQmiWVbXvJ++CRchi5 Mt4An13Cbc6yu0xiivgcO9UKacu3Rpjo =Uaqf -----END PGP SIGNATURE-----
