MMA8652 Power Consumption

[tuurbo46]

Hi,

I have a strange power consumption problem with the MMA8652.  

When this chip is running, and is in standby state, it consumes 5.2mA.  

With the MMA8652 disabled the MCU consumes 2.2mA.

So MCU + MMA8652 running the board consumes 7.4mA.

The MMA8652 functions correctly and reads all angles etc, and this is repeated on more than 3 new build boards.

But I cannot understand why it consumes so much power.  One question I do have is, I have connected both of the interrupt lines interrupt 1 and 2.  I am using interrupt1 and this is active low.  So the MCU pin is setup as in and pull_up.  The second unused interrupt line interrupt2 pin is setup as in and pull_up.  Would this second unused interrupt pin be consuming all the power?

Any ideas or tests would be greatly appreciated.

Look forward to your reply.

Thanks.

Tuurbo46

[david_diaz]

Hello,

The Table 101 from the datasheet shows the expected current consumption in regard with the power mode and ODR (Hz) selected.

Could you please give me more details of your application such as ODR and power mode used?

You may refer to the following document as reference for your project:

https://community.nxp.com/docs/DOC-332453

I hope you find it useful.

Regards,

David

[tuurbo46]

Hi David,

* VCC = 3.3V

* Motion Mode = Transient

* Power Mode = Ctrl_Reg2, 0x01

* ODR = 100Hz

Thanks

Tuurbo46

[tuurbo46]

Hi,

OK so I have tried everything that I can think of, and I still have a power consumption issue.

Just to confirm, I am using active low interrupts, so I am therefore using 4.7k resistors and tying the int I/O pins to VDD 3.3V.  Is this correct?

One other thing, I have tied VDD, VDDIO, to the micro VDD that are all running at 3.3V.  Is this correct?

Also does anybody recommend any further tests that I could try to resolve this problem?

Thanks in advance,

Tuurbo46

[reyes]

Hi,

If you want to use an active low interrupt, I would recommend you to use 4.7 kΩ Pullup resistors on INT1/INT2 and set the interrupt pad into open-drain operation PP_OD bit = 1.

If push-pull interrupt pad is used (PP_OD bit = 0), no pull-up is required.

The power supply range for the MMA8652 goes from 1.95v to 3.6v and its digital interface voltage range goes from 1.62v to 3.6v, hence it can support 3.3v in both VDD and VDDIO.

Have a great day,
Jose

[tuurbo46]

Hi Jose,

The power supply range for the MMA8652 goes from 1.95v to 3.6v and its digital interface voltage range goes from 1.62v to 3.6v, hence it can support 3.3v in both VDD and VDDIO.

Thanks for your reply.

I am going to change the board and power the micro with 1.8V, but this means I cannot power VDD and VDDIO with 1.8V.

Should I therefore power the MMA8652 VDD with 3.3V, and VDDIO with 1.8V, or leave VDDIO disconnected when using a 1.8V micro?

Thanks,

[reyes]

Hi,

Yes, you should power the MMA8652 VDD with 3.3V and VDDIO with 1.8V when using a 1.8V mcu.

SDA and SCL pull-ups should be connected to VDDIO (1.8V).

Have a great day,
Jose

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