Figure 3 : Typical Application.

curacy required, the time taken to sample the input

and the input impedance during that time, while the

maximum value is determined by the required fre-

Thus for a resistive input A/D connector where :

Sample time (Seconds)

Device input resistance (Ohms)

Input voltage (Volts)

k

=

Required accuracy (%)

Charge on capacitor before sampling

Charge on capacitor after sampling

Device input current (Amps)

Thus :

k

100

but

and

k

so that

100

and

Farad

⋅ k

100

so

Farad

k

The calculationfor a sample and hold type convertor

is even simpler :

k

=

Required accuracy (%)

Hold capacitor (Farad)

100

Farad

k

L9700

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