ADuCM330 AUX sensing related inquiries

Hi all

One of the customers inquired about using the ADuCM330 AUX channel.

Previously, used ADuCM330 as Pic 1 connection. This worked fine.

                                    <Pic 1>

Now she wants to use the AUX channel of the AduCM330. (IN+_AUX, IN-_AUX / XINP_AUX, VINM_AUX)

She wondering if the AUX PIN is added to the existing connection method and it works when the sensing position GND is different. (Pic 2)

                                     <Pic 2>

If I have a problem with the configuration, how do I configure it?

Thank you

  • Hi Andrew,

    In the datasheet the absolute input voltage for the current channel is -200mV and +300mV, 
    This is also valid for the auxiliary current channel input.

    Therefore the configuration in Pic2 cannot be used.

    However, as there seems to be only one current path the setup as shown in pic1 is sufficient with respect to current sensing.

    In order to measure/monitor the voltage of a second battery an external voltage divider could be used with the VTEMP/GND_SW or VAUX-/VAUX+ to monitor the higher voltages, basically mimicking the on-chip attenuator but with the required values. One has to ensure that the min/max absolute input voltages are respected.

  • Hi Holger

    Customer provided additional information.

    The customer wants to configure the system as shown below.

    Can the customer configure the circuit in this way?

    A unique point is that one point is common ground and the other point is current sensing with a voltage across the shunt from a separate power supply.

    (Red box part is independent GND.)

    In short
    1) Whether the external independent power load current can be sensed independently.
    2) Allowable withstand voltage between chip ground and shunt signal of independent power supply [V]

    Thank you

  • Hi Andrew,

    I don't think this will work, the voltage of the sensing shunt with respect to the ASIC could potentially exceed the input voltage range for the aux. current channel (-200mV and +300mV)
    The input would be clamped falsifying the measurement. 

    Holger