Capacitor selection for Honeywell HMC5883L

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#1
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Hello all,

I am currently looking at a HMC5883L design and the datasheet has a special note for two capacitors:

Quote:

The two external capacitors should be ceramic type construction with low ESR characteristics. The exact ESR values are not critical but values less than 200 milli-ohms are recommended. Reservoir capacitor C1 is nominally 4.7 μF in capacitance, with the set/reset capacitor C2 nominally 0.22 μF in capacitance. Low ESR characteristics may not be in
many small SMT ceramic capacitors (0402), so be prepared to up-size the capacitors to gain Low ESR characteristics.

There is also some hints that the selection really matters to get the chip working. There are some reports that tantalum caps are bad (ESR == 3R), though actual suggestions for parts are thin on the ground.

The Atmel XPLAIN board hardware notes containing the sensors it not particularly helpful as to their selection:
http://www.atmel.com/tools/AVRSB...

So, has anyone got the device working? What capacitor part numbers did you use for the critical 220nF and 4uF capacitors?

-- Damien

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Ceramic caps, example:
http://n0m1.com/2012/02/27/6dof-...

More importantly pay close attention to the layout guidelines regarding copper fill and current carrying traces under the chip.

Also, watch out for ferromagnetic materials nearby.
I saw an implementation that was nearly unusable due to proximity of a steel mini USB pth connector.
As well, some 60/40 solder that held a weak magnetic field...

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krazatchu wrote:
Ceramic caps, example:
http://n0m1.com/2012/02/27/6dof-...

I may have missed it, but I didn't see a BOM :(

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Right, just standard 0603 size ceramic caps.
http://www.digikey.ca/product-se...

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I use a HMC5843 which is the predecessor of the chip you use.
I have a standard C0603 220nF cap between pins 9 and 14
and I have a 4,7uF 0603 cap + 47uF tantalium on pin 13+15 to ground right next to the pins.

My compass seems to work just fine with those components.