cancel
Showing results for 
Search instead for 
Did you mean: 

Replace 10uF electrolytic capacitor with ceramic capacitor (IIS328DQ)?

SFors.4
Associate

In the datasheet of the IIS343DQ it says that you should use a 10uF aluminum decoupling capacitor (chapter 'Application hints'). In the evalboard it is also shown like this in the schematic but if you look in the BOM you find a ceramic capacitor. So is the aluminium capacitor really necessary (stability reasons?) or could it be safely replaced by a ceramic one? Thank you for your help!

1 ACCEPTED SOLUTION

Accepted Solutions
Peter BENSCH
ST Employee

Welcome, @SFors.4​, to the community!

An electrolytic capacitor with this capacity is usually cheaper than a ceramic capacitor. If one connects an electrolytic capacitor of 10µF and a ceramic capacitor of 100nF in parallel, as the data sheet of the IIS328DQ strictly speaking recommends "Power supply decoupling capacitors (100 nF ceramic, 10 μF aluminium) should be placed as close as possible to pin 5 of the device (common design practice)", then the ceramic capacitor filters the high-frequency switching portions and offers a sufficiently small ESR, while the electrolytic capacitor is the higher-resistance energy store for lower frequencies. Both can of course be replaced by a single 10µF ceramic capacitor, whereby the piezoelectric effect that increases with the capacitance of ceramic capacitors should be taken into account in the design.

Does it answer your question?

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

View solution in original post

1 REPLY 1
Peter BENSCH
ST Employee

Welcome, @SFors.4​, to the community!

An electrolytic capacitor with this capacity is usually cheaper than a ceramic capacitor. If one connects an electrolytic capacitor of 10µF and a ceramic capacitor of 100nF in parallel, as the data sheet of the IIS328DQ strictly speaking recommends "Power supply decoupling capacitors (100 nF ceramic, 10 μF aluminium) should be placed as close as possible to pin 5 of the device (common design practice)", then the ceramic capacitor filters the high-frequency switching portions and offers a sufficiently small ESR, while the electrolytic capacitor is the higher-resistance energy store for lower frequencies. Both can of course be replaced by a single 10µF ceramic capacitor, whereby the piezoelectric effect that increases with the capacitance of ceramic capacitors should be taken into account in the design.

Does it answer your question?

Regards

/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.