I got the cause of this problem! Just wanted to share with the rest of the 8052ians.

Well, since the oscillator freezes between each interrupt, the TH0 and TL0 registers also freeze during the time the micro remains in power down.

That is why the whole thing effectively slows down, since to reach the count 'n'the micro has to spend more time that it would have spent with the oscillator running all the time.

I guess, this is the first time someone has posted the problem and the solution as well!

Hope this will help anyone in the future facing the same problem as
I too faced!

regards,
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