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KL05Z8 Very Low Power mode not working as expected

Question asked by Srdjan Stokic on Nov 16, 2016
Latest reply on Nov 27, 2016 by Hui_Ma



I'm trying to put my board which has a KL05Z8 MCU into VLPS mode. When I do this I get around 200uA of current, which is too high. According to the datasheet, this number should be closer to 2-3uA. The MCU is set to use fast internal 4MHz in BLPI mode, core clock is set to 1MHz, and bus speed to 0.5MHz.


When I run the identical code on the KL05 FRDM board which has a KL05Z32 MCU on it, I'm correctly getting 2.9 uA.

According to datasheets these two chips should be identical, and only their flash/ram size should be different.


On the board there is only the MCU connected to 3.3V and a reset line which goes to 3.3V through a 100K resistor which means that the measured current is certainly going in the MCU itself, there are no other components around it.


What could be the reason for this excess power consumption? Is is possible that there is a problem with MCU itself? I made 20 boards and so far they all seem to exhibit similar behaviour, although the numbers for the current are slightly different.