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Nobody had problems with the LM1036 ?

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Daniel23

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Mar 2, 2011, 1:01:45 PM3/2/11
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I've put together a circuit identical to that in National's Data Sheet.
I get a near to 48 MHz sine wave of about 200 mV out of both outputs.
This is with no input signals. I get this result with several different
chips. I tried on solderless breadboard and a perfboard. Upper side is a
ground plane where all capacitors are tied as short as possible.
I tried first with conventional components (wired) and then with SMT.
I tried also with a ground plane on the upper side where all capacitors
were tied as short as possible.
But all that without any result...

Any ideas?
Thanks!

P.S. sorry for my poor english ...

Phil Allison

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Mar 2, 2011, 5:03:22 PM3/2/11
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"Daniel23"


** Try fitting a 330 ohm resistor in series with each output.

The output stage my not be stable with the capacitance of your scope lead
directly attached.


..... Phil

Daniel23

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Mar 10, 2011, 2:05:12 PM3/10/11
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Phil Allison a écrit :

>> I've put together a circuit identical to that in National's Data Sheet.
> …..

>> But all that without any result...
>
> ** Try fitting a 330 ohm resistor in series with each output.
> The output stage my not be stable with the capacitance of your scope lead directly attached.
> ..... Phil

Thanks Phil,

I have problems to read the NG. I've read yor answer on the web but it
does not appear when I look in the NG ...

I tried with up to 1k in series with the outputs. Only effect: the
amplitude decreased due to low-pass built by the resistor and the input
capacitance of the probe.

I tried with the inputs shorted to ground (instead of 10k). No result.
I tried decoupling the "zener ref" with caps from 100nF to 10uF. No result.
Tried to change the value and the technology (Solid Al or tantal) of the
caps at pin 1,6, and I put a 100nF parallel to these caps. But without
any improvement.

The only way to get rid over the oscillation was to put a 220pF on each
output to gnd. This solution does not satisfy me too well as long I do
not understand what happens exactly...

Now I've sent an email directly to National Semiconductors. I'll wait
what is happening ...

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