In 100BaseFX mode, can you tell me what the receiver common mode voltage and min/max differential swing is for the DP83620?
We have an application where we are ac coupled to an optical module driving CML with ~ 400mV single end swing.
Are there any input jitter or pulse symmetry requirements on the receiver in 100BaseFX mode?
Hi Rich,
As DP83620 is an old part so it is not feasible to find some of the design parameters which are not in the datasheet. But here is what I could find :
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100Base-FX Receiver |
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Vin |
Input differential voltage pk-pk |
0.22 |
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1.8 |
V |
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Jitter tolerance |
Receive jitter tolerance |
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0.45 |
UI |
So if we can insure that the eye diagram at the PHY's receiver pin shows opening more than 0.22V pk-pk for 0.55UI, 83620 should receive it fine.
Also if I understand your application diagram correctly, it is very similar to what is there in datasheet :
And as you mentioned that receiver is also AC coupled (cap on board or usually in fiber transceiver), putting the resistor divider on the receiver pin will take care of the common mode.
On side note, may I know the reason for choosing DP83620. Did you check out our recent 100base-fx part : DP83822? It can help you reduce your BOM.
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Regards,
Vikram
