4 Replies Latest reply on Mar 29, 2017 12:13 PM by userc_38878

ADC_SAR_Seq problem

userc_38878 Apr 8, 2017 1:01 AM

hi all cypress friends,

i run a voltage meter project

so i place a ADC_SAR_Seq , and a analog input

how could i set a right Vref,that could accept Voltage range from 0-5V ,

i saw the Vhref selection have a VDD , but it is 3.3V

Thanks for your help,

david

1. Re: ADC_SAR_Seq problem

JoMe_264151 Mar 29, 2017 1:20 AM (in response to userc_38878)

Welcome in the forum, David.

Because no voltage may be larger than Vdd you will need a resistor ladder to reduce your analog input to 3.3V.



Bob
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2. Re: ADC_SAR_Seq problem

userc_38878 Mar 29, 2017 2:55 AM (in response to JoMe_264151)

but my input range need 0-5v input
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3. Re: ADC_SAR_Seq problem

JoMe_264151 Mar 29, 2017 5:07 AM (in response to userc_38878)

Well, and? The resistor ladder will reduce the 5.0V input to (for instance) 3.0 V. then you do a re-calculation like Voltage = Measured * 5.0 / 3.0;

There is an API to set the gain and offset, so that the count to volt API does this automatically.



Bob
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4. Re: ADC_SAR_Seq problem

userc_38878 Mar 29, 2017 12:13 PM (in response to JoMe_264151)

thanks
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