Other Parts Discussed in Thread: TPS3780, TPS3779,
I make a long push button circuit with CD4013.
The circuit shows below
I use the /Q of second CD4013 to enable the following regulator.
I use lithium battery voltage to control CD4013.
Our customer says there is some error sometimes.
After experiment when lithium battery below 3.5V, there is some error .
I wish when lithium battery voltage under 3.5V, I will turn off the /Q of CD4013. (product power will on turn on)
So I use TLV840NADL35DBVR to reset the /Q of CD4013.
After test, when lithium battery voltage is 3.5V,3.4V, /Q of CD4013 is low so system is off.
When lithium battery voltage is 4V, /Q of 4013 is high,so system is on.
But when lithium battery charging to 3.7V.
I measure the /Q of 4013.
The blue is lithium battery voltage.
The yellow is /Q of 4013.
It seems TLV840NADL35DBVR reset /Q for many times.
Maybe 3.5*(1.05)=3.675=> Hysteresis on VIT– pin
TLV840NADL35DBVR will not judge correctly at 3.6~3.7.
In the voltage supervisor and reset IC tip trick document figure 1-3.
There is a demo circuit.
Because the lithium voltage is a slowly changing voltage.
There may be some problem on judging the voltage.
I do not know how to overcome this point.
If I use TPS3779 or TPS3780 will solve this problem?
Or there is better solution to solve this issue?