Analog Switch Settling-time Calculator

The analog switch settling-time calculator estimates settling time for a multiplexer by calculating the slower of the two time constants for a cascaded RC network, then computing how many of that time constant must pass before the system will settle to within 1%, 0.1%, 0.01% and 0.001% of its final value.

The calculator also estimates the maximum sampling rate possible for a classic A/D converter with S/H input.

The sampling rate is estimated as 1/sqrt( (t_settle+t_transition)² + t_PGA²). This number should be less than the sum of t_ACQ+t_CONV, otherwise the maximum sampling frequency will be limited by the latter. The maximum sampling frequency estimate is shown in megasamples/second to the right of the settling time number.

To use the calculator, enter the switch parameters in R_ON, C_S and C_D and the application parameters in R_SOURCE, R_LOAD and C_LOAD. Tabbing from one field to the other updates the tabular display at right, or click "Calculate".

No special issues are known to exist with this calculator at this time.

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Multichannel Applications (pdf, 607,710 bytes)

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