OPA1S2384: OPA1S2384

Hello Stel,

The hold capacitor is external to the device, this will depend on the type of capacitor used.

Best,

Hasan Babiker 

Hi,

Let me reformulate my question:

How I calculate the discharge time assuming external hold cap value is known = 100pF;

if the ramp is positive is ok, if the ramp is negative the hold cap voltage level is higher

comparative to the new sample value, so the cap has to discharge to the new value.

Add:

[...] "There are several error sources that should be considered when designing a sample-and-hold circuit. The most important ones are: • Aperture Time is the time required for a switch to open and remove the charging signal from the capacitor after the mode control signal has changed from sample to hold.

"[..]

www.ti.com/.../OPA1S2384

Hello Stel,

While the part in set in sample mode, the rate of change across the capacitor will be limited either by the output current of the device, slew rate, or filter bandwidth set by your resistor and capacitor. In terms of the aperture time, the datasheet states that the turn off time of the switch is 15ns. You can use TINA-TI with your known capacitor and resistor values to get a good estimate of what the rate of change across the capacitor will be.

Best,

Hasan Babiker