Hi;
I am working about a LPC824.
In UM10800.pdf at page 322 "Perform a single ADC conversion using a software trigger" it says that The result of the conversion is (4095 x VIN)/(VREFP - VREFN). But I need to know why is that equation and not this other:
The last one indicates a FS between Vrefp and Vrefn.
In this terms, the minimum LSB is:
Can someone help me?
Regards. Daniel.
@Chee Keong Phua, basically I need to know if result is always 0 for any value of Vin=Vrefn.
* The first previous equation is missing a parenthesis between (Vinn-Vrefn)
Thanks and regards. Daniel.
When VIN less than or equal to VREFN, the ADC Count is zero.
@Chee Keong Phua ok, thanks so much. Thus, the equation in UM10800.pdf at page 322 "Perform a single ADC conversion using a software trigger" is wrong. The good equation is this:
result = (4095 x (VIN-VREFN))/(VREFP - VREFN)
Thanks and regards. Daniel.
For single end ADC input, the equation (4095 x VIN)/(VREFP - VREFN) holds since this is a simple ratio metric ADC.
Not sure how the equation with additional -VREFN comes into play.