What determines how fast I can switch between analog switch inputs

Jon Bean1

I am using an analog switch from another manufacturer. Its a 2:1 that has input signals of 125kHz and I am trying to switch between the two using a select signal of 250kHz. But the switch seems not to be able to switch at that frequency as the output is not what I expect. So can someone tell me in a general sense what parameter of the datasheet gives this info? All I can see is the time for the output to change from the select changed. These are in the ns range. But I cant find anything that gives info on how fast I can switch between inputs. Do TI have switches that could do this as I need to find a new solution.

Thanks

Jon

over 8 years ago

0 Ravi Singh over 8 years ago

TI__Mastermind 22965 points

Hi Jon,

In addition to the switching time , the RC time constant formed by switch "ON-capacitance (Con)" , On Resistance" (Ron) & external Load (Rload, Cload) will determine the settling time of the switch.

The precision lab video (link below) has a good overview of the factors influencing settling time behavior.

https://training.ti.com/ti-precision-labs-op-amps-basics-analog-multiplexers-1-0

For part recommendations, can you please share your system level requirements (supply voltage, types of signals, current passing through switch etc.)?

0 Jon Bean1 over 8 years ago in reply to Ravi Singh

Expert 1130 points

The two inputs are 125kHz signals that are output from an opamp buffer. The output of the mux is fed to another opamp buffer. The select signal is switched at 250kHz. The mux supply is 5V.

Thanks

0 Ravi Singh over 8 years ago in reply to Jon Bean1

TI__Mastermind 22965 points

Thanks Jon. What are the Ron/Con/Charge Injection (Qc) specifications of the switch that you are using today?

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What determines how fast I can switch between analog switch inputs