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Is there any note when the scan mode is used?

Latest Updated:03/25/2009

Question:

Is there any note when the scan mode is used?

Answer:

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.   

Suitable Products
SH7144, SH7145
SH7065
SH7058
SH7055
SH7050, SH7051
SH7052, SH7053, SH7054
SH7047, SH7049, SH7105, SH7107, SH7109
SH7046, SH7148, SH7101, SH7048, SH7104, SH7106, SH7108
SH7040, SH7041, SH7042, SH7043, SH7044, SH7045
SH7032, SH7034, SH7034B
SH7032
SH7020, SH7021
SH7018
SH7014, SH7016, SH7017
SH7011