TPS3839 with Bigger Hysteresis

Hi Sam,

When you say that the negative-going threshold voltage can be anywhere from 2.3 to 3.08, are you looking for an adjustable threshold or any threshold in that range will work for your application?

Very Respectfully,
Ryan

Ryan,

Any threshold in that range works. Thank you.

-Sam

Looks great! Thanks!

Ryan,

This part requires a 470k pullup resistor which draws ~5uA at 2.5V supply when reset is low. This seems to overshine the 0.62uA current of the device itself. Is there any way to get the whole system in nanoamp territory?

Thanks,
-Sam

Hi Sam,

Unfortunately that is the reality of open drain SVS devices. To my knowledge we do not have a pushpull SVS that has 100mV hysteresis and is within the nanoamp range.

Very Respectfully,
Ryan

Ryan,

Do we have any resources to build these discretely (comparator, voltage reference...) that would give us these desired specs?

Thanks,
-Sam

Hi Sam,

It may be possible to discretely build a solution for your application; however, I am not personally familiar with the discrete components offered.  You can reach out to those teams using the appropriate forums.

Very Respectfully,

Ryan

Ryan,

Thanks for the support.  I've continued my search here.

-Sam

If you need to delay resetbar transition from high to low on falling Vdd, I have used a diode capacitor ladder on the input pin. The capacitor holds the input pin high (and consequently resetbar high) for a short time until it discharges through the input pin of the TPS3839. It might be called a Miller circuit. The time constant is calculated from the capacitance value and the current draw of the TPS3839. That might not be your use case.

I recall a TI app note about adding hysteresis to an earlier design voltage supervisor (maybe it was just comparators) using feedback resistors. I studied it but it did not seem to apply to the TPS3839. Sorry I don't have a link.