AN2615 datasheet(19/37 Pages) STMICROELECTRONICS

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AN2615

Result

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Result

The result is given for a capacitor value of 100 µF. So the conversion time is long. The

conversion time can be reduced by choosing a capacitor with a lower value but accuracy is

also reduced. Other parameters are as follows:

R = 10 K, V1 = 1.5 V, V2 = 2V and V3 = 3 V

So:

R * C = (10 K) * (100 µF) = 1 s

The input range is taken as +1V to -1V, where mod (Vref) (= 1 V) is less than V1.

The conversion time is in the range 1 to 3 s. The settling time (as shown in Figure 3: Timing

diagram on page 8) is fixed at 1s. The ADC is calibrated by reading two known input

voltages afterwhich Koffset and Kgain are calculated. The input voltage Vin is taken from a

voltage source.

11.1

Positive input

In Figure 13, an example of the readings measured by the converter, which are sent to the

hyper terminal, are shown. Tavg is the average of 16 conversions, and Vavg is the calculated

value in terms of voltage. The difference of the maximum and minimum value among the 16

values is also shown.

Figure 13.

Results for positive input

AN2615 Datasheet(PDF) 19 Page - STMicroelectronics