Hello,
We are testing with the TLV3691 and seeing rise and fall times much faster than expected from datasheet table 6.6.
We're seeing a 8usec delay High to Low in this o-scope shot (below) when we would expect something closer to 20-30usec.
Thank you, Keith
Hi Keith,
Something doesn't look right here. Assuming that RS485 WAKE is the output of the comparator, we are expecting it to switch from high to low whenever VIN- goes above VIN+. The square cursor indicates the time at which the VIN+ goes above VIN-, which should correspond to a low to high switch in the output. I'm assuming we are too zoomed in to see the low to high switch at the output. The high to low switch should correspond to the circled crossing, which looks to have a TPHL of around 36us:
Just as a confirmation, could you change the horizontal scaling such that we can see multiple input crossings as well as multiple output pulses?
A faster response time is to be expected for a large overdrive; see figure 8:
But H-L and L-H should be mostly symmetrical.
I suspect that the comparator has some internal capcitances that are not yet completely (dis)charged when the input switches again. Do you see the same discrepancies with longer pulses?
Hello,
When we disconnect the comparator output we're getting more consistent results.
I will share the schematic in a separate email.
Thank you, Keith
