TLV3604: TLV3604 threshold calculation

Hi,

yes, there IS a problem. Equations (1) and (2) are correct, but both equations are not valid at the same time (!) for an arbitrary Vref. Both equations can only be fullfilled at the same time for only one very certain Vref.

When you solve both equations for Vref and set both equations equal, you will get the following condition for R1/R2:

R1 / R2 = (VT2 - VT1) / (VT1 - VT2 - Q + /Q)

With the given values for VT1, VT2, Q and /Q you get:

R1 / R2 = 1.333333333

Setting this into equation (1) or (2) gives:

Vref = 6.566666667V

So, as you can see the wished hysteresis in combination with the wished threshold voltages cannot be provided with Vref = 5V, but only for Vref = 6.566666667V.

Or by other words, if you insist in Vref = 5V, you cannot freely choose the threshold voltages and the hysteresis.

Kai

Thanks Kai for jumping in. I saw this error a while ago and have new equations to share. I’ll post new information on Monday. I entered them in an Excel spreadsheet that I can upload while waiting to update the datasheet. 
Chuck