Electronic – Are tantalums good for PIC Vcap

capacitoresrpictantalumvoltage-regulator

I understand that ceramics are good at ESR but would like to know if tantalum would suffice for my application.

Some 16 bit PICs require a >4.7uf cap (10uf recommended) low ESR cap for their internal regulator. The datasheet doesn't specify the type of capacitor but only says low ESR.

I have successfully used a 10uf ceramic cap with PIC24EP64GP202;

Can I use a tantalum cap instead?

Does DOM (Date of Manufacture) of the caps matter in this regard?

Does age (in-line use period) of a tantalum capacitor matter? Although I'm not going to use a used capacitor but would like to know this for curiosity.

Do tantalum capacitors age? Shelf life? In-use life?

Best Answer

The PIC's datasheet says less than 1 Ohm ESR and it specifically mentions tantalum as being OK.

The regulator provides power to the core from the other VDD pins. A low-ESR (less than 1 Ohm) capacitor (such as tantalum or ceramic) must be connected to the VCAP pin (Figure 27-1). This helps to maintain the stability of the regulator. The recommended value for the filter capacitor is provided in Table 30-5 located in Section 30.0 “Electrical Characteristics”.

http://www.avx.com/docs/Catalogs/techsum.pdf

Has a lot of information about tantalum capacitor failure modes. It's an interesting read.

Steady-State

Tantalum Dielectric has essentially no wear out mechanism and in certain circumstances is capable of limited self healing. However, random failures can occur in operation. The failure rate of Tantalum capacitors will decrease with time and not increase as with other electrolytic capacitors and other electronic components.

IMO tantalum are fine for this application. I wouldn't be concerned about age unless you have some very special requirements.

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