KL17Z256 overconsumption in I2C communication

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KL17Z256 overconsumption in I2C communication

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Contributor I

Hi,

We are working on a TAG by using kl17Z256 and MMA8451 components. We use a very small battery so we are interested in the very low power modes. We have tested the micro modes and all is ok (@ 8Mhz / 1MHz: RUN = 1300 uA, VLPR = 360uA, VLPW = 270uA, VLPS = 2.5uA, VLLS1 = 0.7uA), as well as MMA works correctly.
The problem is in the I2C communication, the 4.7 Kohm pullups consumes lot of current, so they have been remplaced for 1Mohm resistors. However the consumption of the micro in the communication, working in VLPR, is still very high (750 uA). We expected a consumption of about 360 uA.
Is this overconsumption due to the I2C module? Is there any way to reduce it?

Thank you very much and greetings ...

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Senior Contributor II

We use the KL27 (KL17 + USB) and have off-currents of less than 100uA with several I2C devices.

What are the other devices on the I2C bus doing in this mode?

1M resistors is way out of spec for I2C pull-ups.

Will they charge the bus capacitance that the hardware has at the speed the bus is running at?

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