AD7195 with MIC4427

I want to use AD7195 with AC bridge excitation.

To simplify my design, I'd like to use a MIC4427 for bridge switching.

When using the MIC4427, what pin should I use on the AD7195 to drive the MIC4427? ACX1 and !ACX1 or ACX1 and ACX2? If I understand it properly, more ACX1 and ACX2 as they are dephased?

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  • +1
    •  Analog Employees 
    on Mar 3, 2021 4:19 AM 1 month ago

    Hi, 

    You have to used all of the excitation logic pins. Please take note that in ac excitation, the polarity of the excitation voltage to the bridge is reversed on alternate cycles. When the ac excitation is enabled, the reference inputs along with the analog inputs are inverted. 

    Phase 1: The excitation voltage is applied to the top of the loadcell. 

    Phase 2: The polarity is changed so that the excitation voltage is applied to the bottom of the loadcell and the analog inputs and reference inputs to the ADC are inverted. 

    These 2 conversions are then averaged within the ADC and the averaged result is loaded into the data register.

    Please refer to Figure 50. of the datasheet or to the CN-0155 on how to connect it to the bridge sensor and to the ADC. Please also refer to the same materials on how to configure the AC excitation bits.

    Thanks,

    Jellenie

Reply
  • +1
    •  Analog Employees 
    on Mar 3, 2021 4:19 AM 1 month ago

    Hi, 

    You have to used all of the excitation logic pins. Please take note that in ac excitation, the polarity of the excitation voltage to the bridge is reversed on alternate cycles. When the ac excitation is enabled, the reference inputs along with the analog inputs are inverted. 

    Phase 1: The excitation voltage is applied to the top of the loadcell. 

    Phase 2: The polarity is changed so that the excitation voltage is applied to the bottom of the loadcell and the analog inputs and reference inputs to the ADC are inverted. 

    These 2 conversions are then averaged within the ADC and the averaged result is loaded into the data register.

    Please refer to Figure 50. of the datasheet or to the CN-0155 on how to connect it to the bridge sensor and to the ADC. Please also refer to the same materials on how to configure the AC excitation bits.

    Thanks,

    Jellenie

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