TLV3202: TLV3202 - unexpected simulation result

Hi JJ,

don't overlook the input capacitance of TLV3201. R1 is forming a low pass filter with the input capacitance and makes it impossible for the comparator to toggle in time:

So, a remedy is to decrease R1 and R2 by a factor of ten:

jj_tlv3201.TSC

Kai

Hello Kai,

Thank you for providing that info for JJ and always helping with the forum :) 

Hello JJ,

Please take into consideration the input capacitance of the TLV3201 as Kai mentioned and come back with any further questions that you have.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

Hi Kai, 

Thanks for your information and pointing out the problem on the input capacitance.

However, when I use LTSpice to run the transient simulation by changing the R1 = 33k and R2 = 100k.

There has some bouncing pulse at the output falling edge as shown in the picture below:

There is another circuit without hysteresis setting by removing R1 and R2 as shown in picture below.

This circuitry also has bouncing pulse at the output falling edge.

May I know what is the problem causing the unexpected bouncing at the output pulse?

Regards,

JJ

Hi JJ,

this seems to be an artefact of your simulator. You can try to decrease the time window of simulation by modifying ".tran 5u" to ".tran 1u".

For my taste R1 is still too high and still negatively reacts with the input capacitance of TLV3201. What we need is a way steeper edge at the +input of comparator. Like this, for instance:

Kai