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AD7606 reading is zero

Hello,

we are using the AD7606 ADC (http://www.analog.com/en/analog-to-digital-converters/ad-converters/ad7606/products/product.html) to get values from different sensors.

We use the SPI bus (7,5Mhz clock speed) to read the AD7606 results, using a dsPIC33 Microcontroller.

Sometimes after Power-Up and sometimes while running, the ADC starts returning only  zero (0x0000) on the DOUT lines persistently.

The only way to get back to normal operation is to do the RESET sequence on the AD7606 reset pin.

The datasheet states: "If a RESET pulse is applied during a read, the contents of the output registers reset to all zeros."

Out reset signal is never assigned from the µC after the initial reset and also there is a pull-up resistor on the reset line kepping it high all the time.


Are there any other known ways to get the AD7606 to return only zero ?

The Busy & Firstdata lines are still active, just the output seems to be reset to zero all the time.


   Best regards, Chris

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  • I just verfied what happens if the Reset pulse is high one time during a read cycle. As described in the datasheet. the output resets to zero, but only for the current cycle, the next reading is fine again.

    A short Reset spike could happen in our setup due to EMI, but I am sure is does not happen all the time. If we get a zero result from the ADC it stays zero until a full power cycle of the ADC.

    It seems as if the ADC gets stuck in some interal state which reset the output to zero constantly. Due you have any clue how or why this could happen so I can investigate further in the right direction ?

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  • I just verfied what happens if the Reset pulse is high one time during a read cycle. As described in the datasheet. the output resets to zero, but only for the current cycle, the next reading is fine again.

    A short Reset spike could happen in our setup due to EMI, but I am sure is does not happen all the time. If we get a zero result from the ADC it stays zero until a full power cycle of the ADC.

    It seems as if the ADC gets stuck in some interal state which reset the output to zero constantly. Due you have any clue how or why this could happen so I can investigate further in the right direction ?

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