topic Re: Power Consumption on MCF52223 in ColdFire/68K Microcontrollers and Processors

Power Consumption on MCF52223

GPS — Fri, 23 Feb 2007 05:00:33 GMT

Hi - I need to determine how much current the MCF52223 consumes. The datasheet is silent on the subject (literally, section 2.2 Current Consumption is blank). Can anyone point me to a document that describes this? Or, does anyone have any data that I can use as a rough estimate? I have two designs: one running at 27.5 MHz and the other using the internal 8 MHz relaxation oscillator, I need estmates for both.

Thanks!

Greg

Re: Power Consumption on MCF52223

David_L — Sat, 24 Feb 2007 02:09:41 GMT

Greg, They just posted an updated data sheet with power numbers on the product page. Pretty high numbers, but that is to be expected with the ethernet PHY on chip.

Dave

Re: Power Consumption on MCF52223

GPS — Sat, 24 Feb 2007 05:47:43 GMT

Can you point me to the updated document? The only one that I can find is this one:

http://www.freescale.com/files/32bit/doc/data_sheet/MCF52223DS.pdf

It is dated 04/2006 and section 2.2 "Current Consulmption" is blank. Is there someplace else that these documents are also posted with more recent docs?

Thanks,
Greg

Re: Power Consumption on MCF52223

David_L — Sun, 25 Feb 2007 14:04:32 GMT

Greg,

Not sure where you got that link from. If you go to the product page for the 52233 it show shows the new data sheet which is Rev 3, 2/2007. Just in case you can't get to the product page for some reason, here is a link:

http://www.freescale.com/files/32bit/doc/data_sheet/MCF52235DS.pdf

You will note that there is just one data sheet for the whole 5223X family.

Dave

Re: Power Consumption on MCF52223

GPS — Sun, 25 Feb 2007 20:42:44 GMT

No. That is the 52235 I am using the 52223 - completely different parts (obviously).

Re: Power Consumption on MCF52223

David_L — Sun, 25 Feb 2007 23:13:43 GMT

Yes, of course. Sorry for the confusion. Still, It may be useful to look at the just published numbers for the 52235 with the Ethernet PHY turned off.

Dave

Re: Power Consumption on MCF52223

mjbcswitzerland — Mon, 26 Feb 2007 06:18:43 GMT

Hi

I expect the M52235 value with disabled PHY will be close to the M52223.

I did measure the M52235EVB at 40MHz (but always with active PHY, where connecting a LAN cable makes a big difference). Also ran the test using STOP mode support but didn't get great improvements but this was measuring the complete boards.

The results are here: http://www.utasker.com/docs/uTasker/uTaskerBenchmarks.PDF

In any case the stop mode should be considered sicne it does save current consumption and allows the processor to run without any performance reductions. The uTasker project supports this by adding an optional task which checks for system activity (other tasks scheduled to run or messages waiting to wake then etc.) and if there is presently nothing to actively be perfomred it enters STOP mode.

...
low power task - has just checked that nothing pending and has disabled interrupts
// WAIT or DOZE mode - commanded by STOP instruction (STOP # - writes data to SR and enters stop mode with enabled interrupts)
iInterruptLevel = 0; // mark that no nested interrupts after wake up
asm { stop #0x2000 } // enter STOP mode with interrupt enabled
...

When executing the STOP instruction the processor is frozen but all peripherals work as before. The value 0x2000 is set to the status register when entering STOP mode to enable interrupts again. Any interrupt in the system will immediately wake the processor out of the stop mode and it will continue running from this location without any noticable delays. In a typical network application it can be seen that the processor remains in the STOP mode for maybe >95% of the time. When running with low power support there is no performance decrease since STOP mode is only entered when the processor is idling.

On a Coldfire without Ethernet the current consumption reduction using this method will of course be much more noticable - the PHY is the main mA eater!

Re: Power Consumption on MCF52223

DrSeuss — Tue, 27 Feb 2007 08:54:07 GMT

We are currently work on characterizing these numbers. I think this device will be very similar to the MCF5213 device. There might be a small increase due to driving the USB cable but nothing like the MCF5223x (Ethernet part). In the mean time please use the data from the 5213.