Content originally posted in LPCWare by ptamo on Mon Nov 10 16:09:18 MST 2014
Hi nerd herd,
Thanks for your help, your results are interesting.
The manual says that sleep removes core clock, I do not understand why most of the core power consumption remains. This differs from my experiences in the past. LPC43xx are the first cortex-M I deal with, perhaps is something usual with this architecture.
Sleep mode current at the datasheet is specified at 12Mhz IRC, so you must be right.
Your 84mA Active mode 204Mhz current measurement is far different from my measurements, this gives me hope.
I have tested another of our boards with the LPC4330, this one from a different batch. I have modified my setup to get more precise current readings. I have tested my setup connecting a load to the LPC power rail (3.3v) to verify that my readings work.
Active mode current @204Mhz inside de while(1){} is 160mA higher than deep-sleep current. Deep-sleep current consumption is very similar to current consumption with the microcontroller at reset, this makes sense.
I understand that ResetISR is the first code executed at the micro. The user manual says that after a power-up the core clock BASE_M4_CLK is connected to the outputof PLL1 and running at 96 MHz and the clock source for the PLL1 is the 12 MHz IRC.
If I place a while(1){} loop at the first line of ResetISR current consumption is ~73mA, a datasheet graph states that at 96Mhz typical current consumption is ~40mA. Note that after a debug power up with the debuger attached BASE_M4_CLK is connected to the IRC an runs at 12Mhz.
Using crystal or IRC makes no significant difference.
I have revised our schematics, comparing them to Keil MCB4300 development boards, looking for differences. I have moved some of the configuration pull resistors to test the jumper settings of the Keil development board. No changes found.
We use LPCOpen v1.02 with some patches added. We have considered migrating our projects to newer v2 versions, but lots of changes are required.
We use LPCXpresso and LPC-link2. Today I have migrated from LPCxpresso v7.1.1 to latest v7.5.0 version to see if it makes any difference on power consumption, no success.
Now I have run out of ideas.
We run both LPC4330 and LPC4357 boards from batteries and power optimization is a must for us.
Thanks for your time
Rubén