Capacitance Calculation for Powering Pulsating Load: 100mA for 10mS at 3.3V

  • Thread starter Thread starter Neo11
  • Start date Start date
  • Tags Tags
    Calculation
Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
Sign up Log in
1 reply · 2K views
Neo11
Messages
2
Reaction score
0
I want to build a small circuit which will power a pulsating load. I got a power supply which can provide 3.3V and 2 mA. Now my load requirement is 100 micro amp average and 100 mA for 10 mSec(all at 3.3V). I want to calculate

1. Value of capacitor which will provide 100mA for 10 mS
2. Time duration to sufficiently charge the capacitor(to determine after how much time load current surge can be adjusted)

Can anybody help me to solve this problem?
 
Engineering news on Phys.org
Neo11 said:
I want to build a small circuit which will power a pulsating load. I got a power supply which can provide 3.3V and 2 mA. Now my load requirement is 100 micro amp average and 100 mA for 10 mSec(all at 3.3V). I want to calculate

1. Value of capacitor which will provide 100mA for 10 mS
2. Time duration to sufficiently charge the capacitor(to determine after how much time load current surge can be adjusted)

Can anybody help me to solve this problem?

The equation you want to use is:

[tex]i(t) = C \frac{dv(t)}{dt}[/tex]

Or in simpler form (if you haven't studied calculus):

[tex]i(t) = C \frac{\Delta v(t)}{\Delta t}[/tex]

or,

[tex]\frac{i(t)}{C} = \frac{\Delta v(t)}{\Delta t}[/tex]

This means that the droop in voltage with respect to time is equal to the current out of the cap, divided by the size of the cap.