I have xilinx 95108 I am clocking by 555 timer and testing for some small project. the
95108 is getting heated up when I connect 555 output to an IO pin(1 number). Then i dont understand what to do about it, this is a problem because it rendered my previous chip non programable when I was doing same thing? circuit is(Dip)555 ---> 95108 (plcc 84)-----> cro
I have hand soldered everything on a general purpose board
any body had similar problem?
regards
What is the 555's power-supply voltage?
-a
Sounds like the CPLD is going into a latchup state.
Leon
On the data sheet there are very long rise and fall times for the 555 (100 ns). Maybe you should put some schmitt trigger buffer between 555 and the cpld.
Greetings Klaus
hi, There is 4.5 V supply for entire circuit throughout the board.
I am testing with schmitt trigger today thanx guies Augast15
You can actually use a Schmitt gate as an oscillator. That is what Xilinx did on one of their little CPLD evaluation boards. Just takes a
390 ohm resistor and capacitor.Leon
Can you give the full part number ? You do realise the 95108 will get warm, anyway, because of the high Icc - have you measured just how much current it draws ? 'Getting heated' is not quite good enough...
-jg
Jim's right,
CPLDs are power hungry... 300-400mA is no problem for bigger ones, there's an equation to work it out somewhere... From
You have ICC (mA) = MCHP (1.7) + MCLP (0.9) + MC (0.006 mA/MHz) f
say the valid range is 180 - 250 mA for high performance Then you have to look at the package thermal characteristics for the package you use, (PLCC-84 / PQFP-100 / TQFP -100 / PQFP - 160) In the document
I have some 95288 devices that run at 40-50 degrees, which is backed up by these equations. Note that your finger is quite a good thermometer, if it feels warm, its probably 40-50 degrees, if its not possible to touch for a prolonged period it closer to ~60, and if you simply cant touch it it's ~70, if you look at your finger and see XC95108 burned in it... then it's hotter still =)
Anyways, post more info, an unusually heated CPLD could be due to many factors.
Ben
It's the other way round - fingerprint burnt into the plastic! I once put a finger on a chip that had been inserted into the socket the wrong way round, so I know from experience. 8-(
The chip actually worked when it was inserted correctly, to my surprise.
Leon
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.