# Using ceramic capacitors instead of electrolytic capacitors

I'm using a circuit to charge and discharge a capactior at different rates, where the capacitor has a capacitance of 10uF. I have tested the circuit in a breadboard and it worked well with an electrolytic capacitor, however, when assembling the circuit in a PCB, I have stumbled upon SMT 0805 ceramic capacitors with 10uF. Using one of these would result in a pretty good reduction in space, but would it work with the same results as the electrolytic cap?

My main goal is to make sure the capacitor still charges and discharges as I tested on the breadboard. As the RC constant stays the same with either a electrolytic or a ceramic cap, I believe it would work, but then why would someone use a bigger, more expensive electrolytic cap over a ceramic one?

This is the circuit I'm using, where the testpoint is the input of a analog comparator IC. It's a low current and low voltage circuit(3.3V and 5V).

• they degrade with voltage, so to know for sure it would be nice to understand what are you trying to achieve.
– TQQQ
Commented Jul 19 at 18:36
• The ceramic cap may change value from 10 uF at 0 V to 2 uF at rated voltage. The electrolytic is relatively voltage-insensitive. If you can tolerate the variable capacity, then go for it. Commented Jul 19 at 18:48
• As Neil_UK alluded to, ceramic caps have a capacitance which changes significantly with DC bias. Without knowing more about your application I would not assume identical performance.
– Drew
Commented Jul 19 at 20:04
• What's the maximum voltage across the cap and how much tolerance in the RC time constant can you live with? (Would +/-30% be okay, for example?) Commented Jul 19 at 20:10
• @Drew Specifically, type-II and type-III ceramic caps have a voltage dependence. A 10 μF capacitor is definitely not type-I, but it should be noted. Commented Jul 20 at 5:58