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INA220-Q1: Out of range Voltage values being read from Voltage bus read over I2C

Part Number: INA220-Q1

Hey TI Team, 

We are running into an issue with the INA220-q1 chip being used to read voltages. Not sure if this has to be handled in the ADC or from our end. When we are reading the Bus Voltage Register (address = 02h), with BRNG=1 we read the value 0xFF6A as the raw value. 

based on this 
Overflow bit = 0

Conversion ready = 1

0xFF6A >> 3 = 0x1FED

voltage = 0x1FED * 0.004 (LSB)

voltage = 32.692v 

Is this something that shouldn't have been set in the chip ? Or is it something that the fw on our side has to handle knowing that this value is out of range as mentioned by the datasheet?

This happens very randomly , at other times it is reading the correct voltages which are ~12v. 

Thanks for looking into this and looking forward to your reply ! 

  • Hi,

    Here is what the datasheet says regarding OVF bit:

    There is a possibility that the math doesn’t overflow even if the Vbus voltage is high. For example when the current, therefore power too, are both small. In this case the bit will not be set.

    The theoretical max Vbus value is 8191*4mV=32.764V. Although component breakdown limits it to 26V.

    To summarize, I would throw out the bogus readings in your fw since the chip doesn’t handle it.

    Regards, Guang