LPC4370 - very high power consumption

[lpcware]

Content originally posted in LPCWare by ab2015 on Thu Oct 29 17:51:26 MST 2015
Hi,

I have used devices based on various MCUs, however, I am new to LPC MCU family.
Can someone point me to sample schematics with minimum components required to connect a LPC4370-TFBGA100 MCU (powered by USB bus) with W25Q80BVSSIG flash and XC6227C331PR-G power regulator to a USB Host ? I am trying to test my proto board which is based on the LPC Link 2 schematics, however the MCU is getting very hot and it is consuming up to 300 mA. The MCU boots from the flash correctly and runs the code (the code basically initialize the USB and will make it ready for connections) but after 20 seconds it is getting very hot and after about 5 minutes it will start failing (the USB host will not see the USB device anymore). Exact the same code runs on LPC Link 2 board without any issues. I have tried to reduce the MCU power by switching to an external 3v voltage power source, also used different compatible SPIFI flash chips however the hight consumption still persists. The power consumption may jump from 190mA to 300mA or be in between of those values. It seems like it doesn't matter what code I run, the MCU will still get very hot.
Can someone point me to any component/implementation guidelines or some sample connection schematics?  It seems like I am missing something. Any input appreciated. thank you.

[lpcware]

Content originally posted in LPCWare by ab2015 on Tue Nov 03 21:30:20 MST 2015
I have disabled some of the peripheral features with high current consumption. Still sing USB 0/1 and running HSADC (continuous sampling) at full speed. The current was reduced to  220mA at 3.3V power voltage. It looks better now. Should be able to farther reduce the current. Only the USB and HSADC components are consuming around 60mA in active mode.

Thanks for the tips.

[lpcware]

Content originally posted in LPCWare by rocketdawg on Mon Nov 02 06:50:47 MST 2015
That is good.  Now enable each peripheral, one at a time, and see which one might be drawing excess current.

[lpcware]

Content originally posted in LPCWare by ab2015 on Sat Oct 31 05:37:12 MST 2015
The MCU current is about 12mA to 20 mA if I hold it in RESET mode

[lpcware]

Content originally posted in LPCWare by ab2015 on Fri Oct 30 19:19:53 MST 2015
I was testing the same program on LPC Link 2 (LPC4370) vs my own PCB with same LPC4370 MCU.

[lpcware]

Content originally posted in LPCWare by rocketdawg on Fri Oct 30 12:21:25 MST 2015
Another test.
Hold the LPC in reset and measure the current.
With no power hungry peripherals, the current should be fairly low.
if it is not, then there is some path that you should be looking for that is sucking power.

[lpcware]

Content originally posted in LPCWare by bavarian on Fri Oct 30 04:32:14 MST 2015
Hi,

it is indeed possible to drive the power consumption of the LPC4300 into the region of 200 - 300mA. The power consumption of the internal blocks, if operated on highest performance level, could reach 180mA (excluding the high speed ADC for the moment). Depending on what you connected to the I/O pins you can add the rest.

But of course it is not "normal" to run on such a high performance 100% of the time. If you have such a use case, then I would recommend to use a heatsink.
After startup all peripheral blocks are enabled, so you should disable all the blocks you don't need in your application.

However, your problem seems to be more complicated than this, when you see it working fine on the Link2 board (LPC4320) but not on your own PCB (LPC4370).
I can't explain the difference in power consumption with the differences between the LPC4320 and the LPC4370. But please take care that some of the more power hungry peripherals like EMC, USB1 or the high speed ADC are switched off. Consuming power, getting warm, consuming more power, getting hot etc is a viscous circle in silicon technology, so somehow you need to manage that the dissipated heat from the silicon gets away from it, through the PCB connections and over the package surface.
Try to reduce the speed for the processor and the peripheral blocks as much as possible. For a correct USB functionality you can't go down a lot with VDD.

Simpler than the schematic for the Link2 is not possible, if you leave out some mechanical parts and the line drivers for the SGPIO, then you have the minimum number of components/connections.

Regards,
NXP Support Team.