Hi,
I am having difficulty understanding charge pumps and flying capacitors. Can someone please explain?
Okay with reference to the circuit below:
+5V +5Vswitch_a | | switch_b
FlyingCap
OUT switch_c | | switch_d ------------outputcap--------GND
GND
When switch B and C are on, the cap gets charged to 5V. This I get. Then switch A and D are on and B and C are off. This is where my understanding breaks down.
- There will be a spike current in switch A charging the base of the flying capacitor to 5V. How much current will flow? Is the quantity of this current determined by the size of the flying cap, size of the output cap, output load? What is the relationship to each of these.
- The charge on the capacitor remains constant during the second half of the cycle. So the current during the second half of the cycle must flow to charge the parasitic cap from the other terminal of switch A to ground. Does this mean that this current is independant of the flying cap?
Thanks for listening. Any help is much appreciated
Cheers kaba