Power Supply Decoupling Recommendations - Motorola MC92603 Reference Manual

Power Supply Decoupling Recommendations

5.9 Power Supply Decoupling Recommendations
The MC92603 requires a clean, tightly regulated source of power to ensure low jitter on
transmit, and reliable recovery of data in the receiver. An appropriate decoupling scheme
is outlined below.
Only surface mount technology (SMT) capacitors should be used, in order to minimize
inductance. Connections from all capacitors to power and ground should be done with
multiple vias to further reduce inductance.
First, the board should have about 10 × 10-nF SMT ceramic chip capacitors as close as
possible to the 1.8-V (V
about 10 × 10 nF SMT ceramic chip capacitors as close as possible to the V
device. Where the board has blind vias, these capacitors should be placed directly below
the MC92603 supply and ground connections. Where the board does not have blind vias,
these capacitors should be placed in a ring around the MC92603, as close to the supply and
ground connections as possible.
Second, there should be a 1-µF ceramic chip capacitor on each side of the MC92603 device.
This should be done for both the 1.8-V supply and the V
Finally, there should be a 10-µF low equivalent series resistance (ESR) SMT tantalum chip
capacitor and a 100-µF low ESR SMT tantalum chip capacitor between the MC92603
device and the voltage regulator. This should be done for both the 1.8-V supply and the
V supply.
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5-8
MC92603 Quad Gigabit Ethernet Transceiver Reference Manual
and XV ) balls of the device. The board should also have
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supply.
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