SuperH A/D converter has an on-chip sample hold circuit that keeps sampling voltage, and it has a parasitic capacitance about 20pF.
Electric charge can be charged on parasitic capacitor when it is being sampled, on the scan mode that continuously does A/D conversion, the electric charge that has been charged on parasitic capacitor will be discharged and flown discharge (electrical discharge) current to the A/D input pin.
Especially when the external impedance is high, this discharge current becomes a factor, and the noised voltage is observed in the A/D input pin. The A/D conversion accuracy for this case depends on the external impedance and the operating condition of A/D(such as conversion width of continuous conversion), so please examine circuit constant etc. enough.
|SH7052, SH7053, SH7054|
|SH7047, SH7049, SH7105, SH7107, SH7109|
|SH7046, SH7148, SH7101, SH7048, SH7104, SH7106, SH7108|
|SH7040, SH7041, SH7042, SH7043, SH7044, SH7045|
|SH7032, SH7034, SH7034B|
|SH7014, SH7016, SH7017|