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Niko3's avatar
Niko3
Icon for Occasional Contributor rankOccasional Contributor
3 years ago

very noisy outputs on EPM3064

With a very simple circuit the outputs of an EPM3064ATC44 are very noisy, see attachment. The 1 kHz clock is visible on the outputs with very high needle pulses. These pulses are similarly on all 7 o...
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_AK6DN_'s avatar
_AK6DN_
Icon for Frequent Contributor rankFrequent Contributor
3 years ago

Without seeing your schematic and PCB layout it is hard to make any significant comments. That being said:

What does your input clock signal look like? Is it monotonic with no noise?

Can you zoom in on a transition on the data? Interesting to see what an output transition looks like in detail.

What does the power rail look like, wrt noise?

I have multiple EPM7064S and EPM3064A parts on boards (using PLCC packaging) and don't see such issues.

Niko3's avatar
Niko3
Icon for Occasional Contributor rankOccasional Contributor
3 years ago

You can find the schematic and the layout in the attachment.

In the layout I planned to use a socket for the EPM3064 chip. I found a small one in the internet, but it does not meet the specified dimensions of a TQFP44 chip. With the socket the chip cannot be programmed at all.

Therefore I made a second version with the chip soldered directly on the board. For the tests I only mounted the chip, the JTAG socket, the 4 blocking capacitors and some pins for power supply and input/outputs.

The layout is shown in a version with highlighted ground and VCC.