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AD7779 Reset while using Mux

Question asked by ndomblides on Mar 1, 2017
Latest reply on Mar 2, 2017 by Lluis

Hi,

 

I'm using AD7779, in SPI control mode.

Just after initialization onf the device (configuring internal registers), I'm calibrating each active channels (Offset and Gain). So I'm changing ADC_MUX_CONFIG register to 0x14 to connect REF-/REF- ==> Calibration of the Offset, every thing works fine then I change ADC_MUX_CONFIG register to 0x08 to have access to 280mV reference voltage to calibrate the Gain.

And all my configuration resets just after changing ADC_MUX_CONFIG register value.

 

My configuration is the following :

CH0 : Inactive

CH1 : Active, PGA=4, RX_MUX active (config register = 0x90)

CH2 : Inactive

CH3 : Active, PGA=4, RX_MUX active (config register = 0x90)

CH4 & 5 : Inactive

CH6 : Active, PGA=1, RX_MUX active (config register = 0x10)

CH7 : Inactive

 

I have already seen something like that. The ADC used to reset while using CH0 with RX_MUX active and DC_MUX_CONFIG = 0x08.

 

Do you have any clue about what is happening ?

 

Thank you for your help.

 

Nicolas

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