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PMD100 puts a lot of noise into the power supply ? some results ...

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I took out my scope today and did some measurements on my Rotel 991 CD player .... what a surprise ... please see if the following noise (p-p) figures make sense (the measurements were taken on the actual pins of the IC):

PMD100 (really noisy)
Vdd1 : 400mV (!!!!!!)
Vss1 : 20mV
Vdd2 : 30mV
Vss2 : 55mV

2 x PCM63s
All around 5mV, so nothing special.

So how come the Vdd1 from PCM100 has 400mV noise on it??? And how come the grounds (Vss) are so noisy also??

The power supply of Vdd1 is regulated and passed through a 4.7uH inductor, the trace before the inductor is clean, but after the inductor (just before entering into the PMD100), there is the 400mV noise.

Can this noise be get rid off?

Can the ground noise be get rid off?

Thx

PW


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Topic - PMD100 puts a lot of noise into the power supply ? some results ... - PW 06:30:38 08/14/01 (12)


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