Are there any internal pull-ups on SPI line (as on SDO PIN) on LIS2DH?

[DJord]

Dear all,

My name is Darko Jordanoski. I am responsible for hardware development at Kessler group.

I am currently working on a project: data logger, and using LIS2DH as an accelerometer. 

The device is used in two modes: Normal and Sleep mode.

On sleep mode, the device is powered from internal battery and we are looking for the lowest power consumption possible. The Accelerometer is in low power mode (8bit), Stream-to-FIFO, 50Hz, and we are achieving 6uA current consumption as described in datasheet.

However, in sleep mode, the microcontroller pins are in HIGH Impedance state, including the SPI line. This is where we are facing with a problem, because when pin SDA, SCL, CS (SPI) on the accelerometer are left floating, current consumption is much higher. 

One solution is to implement a pull-up resistors, but that will require a pcb redesign.

My QUESTION is: are there any internal pull-ups (as on SDO PIN) or any other possible solution?

Thank you!

Darko Jordanoski

Hardware Electronics Team Leader

Tel.: [phone]

eMail: [e-mail] | Web: www.kessler-group.biz

[Eleon BORLINI]

Hi Darko, some questions just for my understanding: at which Vdd and VddIO are you working? Is Vdd>=VddIO?

Btw, is it strictly not possible for you to drive the MCU gpio during the sensor sleep mode?

Regards, Eleon

[DJord]

Hi Eleon,

VDD = VDD_IO = 3V3

It is not possible to drive gpio's on the MCU in stand-by mode (not sleep, i apologize), i.e. all pins are in high impedance state except NRST, Wake UP pin and RTC Out.

Accelerometer wakes up the MCU with an interrupt on Wake UP pin.

Thank you.