About AD7175-8 input range?

Dear Sir:

               I have some confuse of AD7175-8 input range as below:

I tried to check datasheet of AD7175-8 page 3 to knew AD7175-8 input range is +(-) VREF and VREF range is 1~AVDD1, then datasheet tell us AVDD1 range is 4.5~5.5V , but ratings of input range only  -0.3V~AVDD1~+0.3V.

Does AD7175-8 can support differential and single end +(-)5 V input range? How about AD7173-8, It also can support +(-)5V input range?

I still confused need to clarify, Can I understood as AD7175-8 can support differential input range is+(-)5V and single end input range is +(-)2.5V , right?

 

Best Regard

Jason

  • 0
    •  Analog Employees 
    on May 23, 2016 12:24 AM

    Hi Jason,

    My apologies for the delay in getting back to you.

    The AD7175-8 and AD7173-8 can handle differential voltage ranges of up to +(-) 5V.

    The Analog Input Voltage rating which is -0.3V to AVDD1 + 0.3V as stated in the Absolute Maximum Ratings section of the datasheet is with reference to AVSS. Since the differential input voltage is calculated as AIN+ minus AIN-, as long as the absolute maximum rating is followed, a differential voltage of +(-) 5V should be attainable.

    For example, if you set

    AVDD1 = 5V

    AVSS = 0

    REF+ = AVDD1

    REF- = AVSS

    The Absolute Maximum Ratings says that the Analog Input Voltage cannot go beyond to -0.3V to 5.3V but the differential input voltage can be anything from +(-) VREF which is equal to +(-) 5V.

    AIN+     AIN-     Differential Input

    0           5.0V     -5.0V

    2.5V     2.5V      0

    5.0V     0            5.0V

    For single ended inputs, since one of the inputs is fixed at a constant voltage level, a +(-) 5V voltage range is not possible as it would violate the absolute maximum rating of the device. For example, using the same setting as above, if AIN- is held at 0V, only an input voltage range up to +5V is possible for AIN+ because applying a negative voltage less than -0.3V would damage the device.

    Hope this helps.

    Regards,

    RC