Yes, I am now wondering how do I apply in this equation.Have you ever heard of an RC Time Constant?
Nope it’s not a home work. It is circuit to measure capacitance(10470pF). Originally, there was no R and C(470pF). Some one add them later for there filter purpose. Point A is connectd to comparator to trig my FPGA to stop counting clock and back calculate to C. Could you guide me how did you calculate it? I am kinda rusty now.Is this homework?
How exact an answer do you want?
By hand calculation I get 313μs.
What does "it need to be accurate" mean?I couldn’t now. Someone add those in the circuit, not knowing that they will impact my circuit. What I can do now is to find its transfer function and it need to be accurate. Thank you.
If it's a circuit to measure the capacitance, then why do you want to know the specific time it takes Point A to reach 2.5 V for that specific value of capacitance? How does that help you measure that value when you don't know it?Nope it’s not a home work. It is circuit to measure capacitance(10470pF). Originally, there was no R and C(470pF). Some one add them later for there filter purpose. Point A is connectd to comparator to trig my FPGA to stop counting clock and back calculate to C. Could you guide me how did you calculate it? I am kinda rusty now.
Thank you!!!
It will be:Here is your first hint.
How much current is flowing through R1?
My first approximation pegs the time to be about 300μs to reach 2.5V.Doesn't the answer depend on the nature of the switch and how fast the voltage rises across the switch and if the switch bounces or not. With a sub microsecond risetime and no bounce the transition through 2.5 V is so fast you can't see it, and point A is at 10V pretty quick?