Reply by rtstofer September 17, 20082008-09-17
--- In l..., "kathy_wright_ca"
wrote:
>
> thank you very much! This is certainly NOT mentioned in the UM or
> the errata and seems to be in conflict with the block diagrams in
> both documents that indicate that the other power domain is the
> Vbat/RTC area.

Vbat/RTC is the 3d power domain for the device.

Separating the core power from the IO power is quite useful if the
application requires minimum power with the core running. Clearly
this is for some kind of battery powered operation.

It also implies that everything external to the uC can also be powered
down because it is probably a bad idea to backfeed power into IO pins
when the IO Vdd is off.

I don't think it would apply to anything I play with.

Richard

An Engineer's Guide to the LPC2100 Series

Reply by kathy_wright_ca September 17, 20082008-09-17
thank you very much! This is certainly NOT mentioned in the UM or
the errata and seems to be in conflict with the block diagrams in
both documents that indicate that the other power domain is the
Vbat/RTC area.
--- In l..., "rtstofer" wrote:
>
> --- In l..., "kathy_wright_ca"
> wrote:
> >
> > I've used the LPC213X in the past and moving up now. It has
separate
> > inputs for a DC-DC converter but I'm finding little on that this
> > acutally does and what happens if I leave it open. Can someone
point
> > me in the right direction? (I've looked through the data sheet
an
> > UMand searched various versions of DC-DC Converter without
yielding a
> > good understanding)
> >
> > Kathy
> > Check Section 7.24.4.4 "Power domains" of the Datasheet (not the
UM).
>
> Basically, the DC-DC Converter allows the designer to shut down the
IO
> system and keep the core running because they are in different power
> domains. Externally, it doesn't matter but I would bet the core is
> running at 1.8V (or lower) and the reason they call it a DC-DC
> converter is that it steps 3.3V down to the core voltage as well as
> providing a separate domain.
>
> Richard
>

Reply by rtstofer September 16, 20082008-09-16
--- In l..., "kathy_wright_ca"
wrote:
>
> I've used the LPC213X in the past and moving up now. It has separate
> inputs for a DC-DC converter but I'm finding little on that this
> acutally does and what happens if I leave it open. Can someone point
> me in the right direction? (I've looked through the data sheet an
> UMand searched various versions of DC-DC Converter without yielding a
> good understanding)
>
> Kathy
>

Check Section 7.24.4.4 "Power domains" of the Datasheet (not the UM).

Basically, the DC-DC Converter allows the designer to shut down the IO
system and keep the core running because they are in different power
domains. Externally, it doesn't matter but I would bet the core is
running at 1.8V (or lower) and the reason they call it a DC-DC
converter is that it steps 3.3V down to the core voltage as well as
providing a separate domain.

Richard

Reply by kathy_wright_ca September 16, 20082008-09-16
I've used the LPC213X in the past and moving up now. It has separate
inputs for a DC-DC converter but I'm finding little on that this
acutally does and what happens if I leave it open. Can someone point
me in the right direction? (I've looked through the data sheet an
UMand searched various versions of DC-DC Converter without yielding a
good understanding)

Kathy