Problems with ITG-3200's chargepump

By pieceof8 , 11 June 2012

I use the ITG-3200 gyroscope-sensor on ten PCBs. The schematic was designed accordingly to the datasheet Rev. 1.7 from 08/02/2011 at page 15.
I connected Vlogic and Vdd to 3.3V. This voltage has a rise time of 680 usec.
The rise time met the power up recommendations in section 4.4 of the datasheet. The CLKIN-Input is connected to ground.

After initialization of the registers i can read the following values:

    REG_WHO_AM_I: 0x69
    REG_PWR_MGM: 0x03
    REG_SMPLRT_DIV: 0xff
    REG_INT_CFG: 0x01
    REG_DLPF_FS: 0x1e


I assume that my i2c-routines working right on an ATmega1281 from Atmel. Nevertheless i read nearly constant values from the output registers during movements and rotations.

The CPOUT voltage rises after power-on to 25V. After 2 ms it drops to 2V. I guess this is the reason for the nearly constant values.

If I set the bits for X- and Y-Axis-Standby, using only the Z-Axis, most of my ten sensors give a proper output value in the GYRO_ZOUT_H/L-registers. The CPOUT-voltage remains at 25V in this case.

Sees anybody a possibility to get the whole sensor to work, or is this behavior a result of an known mistake?

Thanks,
Henning
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