Circuit component clarification

[electronicsLearner77]

This is a UART circuit i am referring to
The top L45 600 Ohm, i assume it is inductor but it mentions as Ohms at several places in the schematic for each power source. Two questions are
1. Is it inductor or resistor and the ohm is printing mistake?
2. What is the purpose of placing the component at that place? My understanding is the inductor does not allow current to raise fast, hence to avoid spikes in current the inductor is placed at that point. Am i correct?

 

[Harald Kapp]

This is a ferrite. It is given in Ω because that is the characteristic impedance at a certain frequency. WIthout the information about this frequency the impedance is not worth much.
Such components are used to let pass DC and low frequeny current, but block high frequency currents. Thus switching noise is kept away from other parts of teh circuit. A capacitor such as C328 is essential for this application. This capacitor delivers teh high frequency current components that are blocked by the ferrite.

 

[electronicsLearner77]

This is a ferrite. It is given in Ω because that is the characteristic impedance at a certain frequency. WIthout the information about this frequency the impedance is not worth much.

But how to get the information about the frequency? It is USB to serial interface, so i need to find the frequency which will affect this communication?

This capacitor delivers teh high frequency current components that are blocked by the ferrite.

If the capacitor is allowing the high frequency current components that are blocked by the ferrite, then what is the purpose of the ferrite?

 

[Harald Kapp]

But how to get the information about the frequency?

From the datasheet. If the specific part type is not given in the bill of materials of the circuit, you can only guess.A good starting point is the operating frequency of the circuit behind the ferrite, in your case the UART.
For hobbyist purposes the ferrite may not be a critical component as you usually don't have to pass EMC certifications - unless your circuit creates noise that disturbs e.g. radio reception of your neighbours.

If the capacitor is allowing the high frequency current components that are blocked by the ferrite, then what is the purpose of the ferrite?

The capacitor limits the high frequency components to that small part of the circuit, ideally to the chip. These high frequency components do not leave this part of the circuit - well made layout and construction of the pcb assumed. Without the ferrite the high frequency currents could stray throughout the circuit, finding long traces that work as antennas to radiate noise.

Here's an in-depth explanation how ferrites are used.