Buffer capacitor?


I'm going to make a PCB for an AS5311 (high resolution magnetic linear encoder) and the datasheet states the following:

For 5V operation, connect the 5V supply to pin 19 and add a 2µF…10µF buffer capacitor at pin 18.

is "buffer capacitor" a regular capacitor or a special one? it would be great to know this since I dont want to spoil the AS5311. I found this diagram and the symbol for this capacitor seems to be different

I assume pin 18 is VDD3V3.

Perhaps they meant "decoupling capacitor", because I've never heard of a buffer cap. Just use a regular ceramic or electrolytic.

Buffer is just the name of what it is doing, it is just a capacitor. The two symbols denote polerised and non polerised capacitors. The big unfilled in box is the +ve terminal and the other is normally a filled in black box which is the -ve terminal. You can't easly get big value non polerised capacitors.

It's a regular capacitor. They should have written "capacitor as a buffer". Also the picture shows "LDO" as voltage regulator, those do not need a ceramic decoupling capacitor at the output (the 780x series do).

2.2uF to 10uF of MLCC is what they mean.. Its decoupling for the internal circuitry which runs at 3.3V (from the on-chip LDO regulator when 5V is connected to Vdd5V.)

I've used various of the Austria Microsystems magnetic encoder chips, just not that particular one. Clever devices (still not as cheap as I'd like though).