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LM96194 AD_IN6/7 voltage sensing error

Other Parts Discussed in Thread: LM96194

Hi.

In the Voltage Monitoring circuit using LM96194, the value read from registers corresponding to AD-IN1 to AD_IN5 is as expected (i.e. close to 0xC0). The inputs AD_IN 1 to AD_IN3 are scaled by an external resistor divider to get a nominal voltage of 0.91V. This value (0xC0) when multiplied by a scaling factor (Input voltage/192) gives an actual input voltage applied.

  1. For AD_IN6 and AD_IN7 the inputs (2.5V and 5V) are given through resistor dividers such that the divided voltage at the input pin is 0.984V.
  2. The value read from registers corresponding to AD-IN6 to AD_IN7 is 0xBA and 0xB5 respectively instead of 0xC0 (nominal) value.
  3. These values (0xBA and 0xB5) when multiplied by a scaling factors (13.02mV and 26.04mV) does not give the actual input voltages applied.

As I understand the AD_IN6 & 7 pins have internal divider resistors (sum is 140K). Can u please let us know what care should be taken in accounting for the error due to internal resistor dividers while calculating the scaling factors.

Regards,

Sachin.