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DSP563xx Current consumption in STOP Mode

Started by Alexander Trica May 24, 2005
Hi,

I am using the DSP56374 and I am testing the current consumption in STOP
Mode. The datasheet says that in STOP mode the DSP should not consume
more than about 2 mA. (core: about 1.2mA; I/O current: about 1.2uA)

I have a current consumption of about 11 mA (core + I/O). The core
current consumption seams to be great (i have about 1.3 mA) But the I/O
and PLL current is much higher (I/O: about 4 mA, and PLL about 5 mA).

Well, how ever - the current consumption of the I/O part of the DSP
depends on the number of peripherals connected to the DSP via GPIOs. All
GPIOs that are not used are pulled high or low. Most of the GPIOs are
configured as GPIO disconnected.

Are that typical values for that DSP? Does anybody have also tested the
current consumption in STOP Mode? What are typical current values of
other DSPs in the 563xx series?

Best Regards
Alex



Alexander,

It's kind of surprising to see they even tried to spec I/O current,
especially without providing the conditions under which it was
measured. The I/O current will vary greatly based on how the I/O is
connected. Most likely they took the measurements under a "best case"
scenario which would never exist in a real application. The only
current consumption values I would put any faith in are the core values
since that is independent on any external circuitry...

--
dB
--- Alexander Trica <motorola@moto...> wrote:
> Hi,
>
> I am using the DSP56374 and I am testing the current consumption in
> STOP
> Mode. The datasheet says that in STOP mode the DSP should not consume
>
> more than about 2 mA. (core: about 1.2mA; I/O current: about 1.2uA)
>
> I have a current consumption of about 11 mA (core + I/O). The core
> current consumption seams to be great (i have about 1.3 mA) But the
> I/O
> and PLL current is much higher (I/O: about 4 mA, and PLL about 5 mA).
>
> Well, how ever - the current consumption of the I/O part of the DSP
> depends on the number of peripherals connected to the DSP via GPIOs.
> All
> GPIOs that are not used are pulled high or low. Most of the GPIOs are
>
> configured as GPIO disconnected.
>
> Are that typical values for that DSP? Does anybody have also tested
> the
> current consumption in STOP Mode? What are typical current values of
> other DSPs in the 563xx series?
>
> Best Regards
> Alex >
>
__________________________________




Hi Alexander

Using the DSP56311 we were able to achieve very low power consumtion in the STOP mode.
If my memory serves me correctly it was very close to what the datasheet had specified for the STOP mode.
We disabled the PLL before going to sleep which saved quite a lot of current. The PCTL register controls the PLL
state during STOP. However, with the PLL disabled during STOP, the wakeup time is much longer because the PLL has to settle.

Hope this helps

Cheers

-----Original Message-----
From: Alexander Trica [mailto:motorola@moto...]
Sent: Tuesday, May 24, 2005 6:41 AM
To: Motorola List
Subject: [motoroladsp] DSP563xx Current consumption in STOP Mode Hi,

I am using the DSP56374 and I am testing the current consumption in STOP
Mode. The datasheet says that in STOP mode the DSP should not consume
more than about 2 mA. (core: about 1.2mA; I/O current: about 1.2uA)

I have a current consumption of about 11 mA (core + I/O). The core
current consumption seams to be great (i have about 1.3 mA) But the I/O
and PLL current is much higher (I/O: about 4 mA, and PLL about 5 mA).

Well, how ever - the current consumption of the I/O part of the DSP
depends on the number of peripherals connected to the DSP via GPIOs. All
GPIOs that are not used are pulled high or low. Most of the GPIOs are
configured as GPIO disconnected.

Are that typical values for that DSP? Does anybody have also tested the
current consumption in STOP Mode? What are typical current values of
other DSPs in the 563xx series?

Best Regards
Alex ------------------------ Yahoo! Groups Sponsor --------------------~-->
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Hi Keith,

I am using an external crystal of 16 MHz. I stopped the PLL before I go
into stop mode, so I think I did every thing right! :) I don't need the
PLL right before or right after the STOP mode, so disabling the PLL
would be the best way.

I have done some fine-tuning today and now I have about 10.8 mA of
current in STOP Mode. That would be core current AND I/O current.
Looking at the I/O section I connected the SPI, all 4 Interrupts and 3
or 4 GPIOs to peripheral circuits. Sice I am using the 52-pin device of
the 56374 there will be only one ESAI Interface connected soon. I think
the current consumption will rise again with the connected ADCs to the
ESAI interface.

Thanks @ all for answering.

Alex Keith Kondakor wrote:
> I have an intrest in using this part soon in a very power critical
> application so would like to help.
> What you have not said is what clock signal you have going into the extal.
> Small level or very high speed clocks will casue higher power requirement.
> Do you stop the PLL during stop?
> If you need to keep it going try reducing the comp freq i.e. set the
> divider.
>
> Keith