Hello!
In one of my project I use TPS3809L30QDBVRQ1 type of a voltage supervisor. It has fixed reset delay time of a 200 ms (typical) and detection delay time (tPHL) of an around 1 us. I use this voltage supervisor to measure voltage of Lithium-ion capacitor to prevent voltage drop below minimum recommended voltage. Exactly this IC is connected to EN input of high-side switch...
I use pulse load on an output of the high side switch and sometimes the voltage for a very short time (two pulses per second, where each pulse is shorter than 50 ms) drops under threshold voltage of the voltage supervisor and this disable the high-side switch. I would like to extend the detection delay time of voltage supervisor, but at the same time I don't like to impact also on the reset delay time. Because I can't find any supervisor with possibility of changing detection delay time (normaly is possible to set a reset delay time), i have next idea to do this:
!RESET output of a supervisor connected via schottky diode to a capacitor (new !RESET output), so when the !RESET ouput rising, the voltage of a capacitor will rise very fast because of a very low resistance of diode. When !RESET output goes from high to low, there will be also resistor connected from capacitor to !RESET output (in parallel to diode which is now in oposite direction - closed), so the voltage on the capacitor drops slowly (depends on RC constant). Detection delay time in this example depends on R and C value and also on Vth_en voltage of high side switch.
Do you have any other more simplier idea maybe?
Many thanks,
Kind regards,
Dejan.
