Hello John,

But how can i chance to a schematic to a -15V, because i saw a app note and i only see possitive voltage

See:

http://www.ti.com/lit/an/slva317b/slva317b.pdf

and:

http://www.ti.com/lit/an/slva540/slva540.pdf

Sorry to ask again but do you have a cheaper solution?

You may get by with a lower current part such as TP54160.  You have to derate the current by a factor of (1-D).  I'll leave it to you to make the calculation.

The TPS54260 is a obsolete product? I can't find it sorry

Sorry i mistake, TP54160 not TPS54260

TPS54160 is active, but you may want to consider the improved TPS54160A with tighter EN specs.

the LM2574 can give -15V output with 500mA?

I don't support that part, but probably not.  You have to calculate the peak switch current in inverting buck boost mode.  It will be higher than the load current by a factor of 1-D plus Ilp-p/2.  the app note I referenced earlier will tell you how.

I saw the TPS54060, dou you think that gives me -15V and 500mA?

So in need to chose a DC-DC with a bigger rate current and select the rith inductor to give 500mA when is on and to charge de caps when is off, that is right?

Right, you can calculate the required peak current then chose the appropriate converter.  The app note should contain what you need.