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ADS8328: ADS8328

Roi Kobo
Intellectual 650 points
Part Number: ADS8328
Other Parts Discussed in Thread: ADS8900B,

Tool/software:

Hello

I'm using the ADS8328IBPW at VA=5V, VBD=2.5V, REF+=4.096V, REF-=0V 

From data sheet, SPECIFICATIONS : TA = –40°C to 85°C, +VA = 4.5 V to 5.5 V, +VBD = 1.65 V to 5.5 V, VREF = 4.096 V, and fSAMPLE = 500 kHz

VIH High-level input voltage   , 5.5 V ≥ +VBD ≥ 4.5 V , 0.65 × (+VBD) +VBD + 0.3 

1. Why in the test condition the 5.5 V ≥ +VBD ≥ 4.5 V and not 5.5 V ≥ +VBD ≥ 1.6 V

2. If the VBD in my design is 2.5V when VA is 5V,  the VIH can be  > 2.5V ?

Roi

  • 0
    TI__Expert 7815 points

    Hi Roi,

    Thanks for your question. The two consequences of lowering the VBD voltage is the impact it has on VIL/VIH levels and the speed of the ADC. Looking at a similar ADC, the ADS8900B, which was manufactured using the same process, we can see the VIH/VIL levels are highlighted below at VBD = 2.5V. You can assume these levels are also true for ADS8328.

     

    If you notice the below table taken from the ADS8900B datasheet, the max SCLK speed is also dependent on the digital voltage rail. However, as the ADS8328 natively only supports ~20MHz, we do not expect this to be impacted.

    Best regards,

    Samiha