Sleep mode power consumption

sjackson · ‎2007-04-11

Posted on April 11, 2007 at 18:43

sjackson · ‎2011-05-17

Posted on May 17, 2011 at 09:41

I am interested in what people have observed in terms of power consumption while in sleep mode. I've been using a STR912FAW44 (rev F) with core voltage at 1.8V and I/O voltage at 3.3V.

While in sleep mode, I observe core current draw to be about 30uA.

I/O current, however is 3mA (that's with my J-Link JTAG pod plugged in. If I remove it the current goes UP to 5mA). I find that this is the lowest current number I can get and have to set bits to put almost all peripherals into a reset state before entering sleep mode to achieve it (I leave peripherals required to wake the chip up running).

I am using an IAR STR912-SK evaluation board, modified to remove components that could be causing additional current consumption.

If anyone has observed a lower current, please let me know what it is and how you achieved it!

Thanks.

mohamed23 · ‎2011-05-17

Posted on May 17, 2011 at 09:41

Dear SJackson,

Could you please inform me how you measure the current, if possible to provide a figure of IAR Board with your modification and jumpers positions and of course your test points using amperMeter. :p

Thanks :o

rave

[ This message was edited by: Rave on 11-04-2007 22:05 ]

sjackson · ‎2011-05-17

Posted on May 17, 2011 at 09:41

To measure current, you basically have to hack up the board. I removed the 3.3V and 1.8V regulators (VR2(1.8V) and VR3(3.3V) on the board) along with resistors R36 and R38 to help minimize extra current draw. Then I attached wires to the middle pad of each regulator footprint (the output pad) and used an external supply to provide 1.8V and 3.3V. Just hook your ammeter in series with whichever voltage line you want to measure.

I removed various other parts on the board which I thought could affect current draw (such as U1 or the power LED; I removed/disconnected almsot everything but obviously don't remove things you want to use) and measured my current. This basically involves a lot of time staring at the eval board schematic that IAR provides (and it is easy to miss things so maybe I did/didn't do something I shouldn't/should have).

Hope that helps you out.