Analog Switch Settling-time Calculator

A tool to estimate settling time and multiplexed sampling rate for an idealized multiplexer.

Device / Application Data

RSOURCE   ohms
RON   ohms
RLOAD   ohms
CS (OFF)   pF

CD (OFF)   pF


Transition time   ns

Prog. gain amp.
settling time


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( (tsettle+ttransition)2 + tPGA2). This number should be less than the sum of tACQ+tCONV, 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 RON, CS and CD and the application parameters in RSOURCE, RLOAD and CLOAD. 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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Related Information

Multichannel Applications (pdf, 607,710 bytes)

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See the Analog Multiplexer Settling-Time Calculator