SLAU846B June 2023 – November 2024 MSPM0G1105 , MSPM0G1106 , MSPM0G1107 , MSPM0G1505 , MSPM0G1506 , MSPM0G1507 , MSPM0G1519 , MSPM0G3105 , MSPM0G3105-Q1 , MSPM0G3106 , MSPM0G3106-Q1 , MSPM0G3107 , MSPM0G3107-Q1 , MSPM0G3505 , MSPM0G3505-Q1 , MSPM0G3506 , MSPM0G3506-Q1 , MSPM0G3507 , MSPM0G3507-Q1 , MSPM0G3519
The SHORT bit shorts the comparator inputs. This can be used to build a simple sample-and-hold for the comparator (see Figure 13-6)
The required sampling time is proportional to the size of the sampling capacitor (CS), the resistance of the input switches in series with the short switch (RI) and the resistance of the external source (RS). The sampling capacitor CS should be greater than 100pF. The time constant, Tau, to charge the sampling capacitor CS can be calculated with Equation 22 .
Depending on the required accuracy, use 3 to 10 Tau as the sampling time. With 3 Tau the sampling capacitor is charged to approximately 95% of the input signals voltage level, with 5 Tau it is charged to more than 99%, and with 10 Tau the sampled voltage is sufficient for 12-bit accuracy.