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Lattice Semiconductor
ORCA ORSO82G5 Data Sheet
98
Recommended Power Supply Connections
Ideally, a board should have four separate power supplies as described below:
TX-RX digital auxiliary supplies.
The TX-RX digital and auxiliary power supply nodes should be supplied by a 1.5 V source. A single 1.5 V source
can supply power to TX-RX digital and auxiliary nodes.
TX-RX analog, guardband supplies.
A dedicated 1.5 V power supply should be provided to the analog power pins. This will allow the end user to mini-
mize noise. The guard band pins can also be sourced from the analog power supplies.
TX output buffers.
The power supplies to the TX output buffers should be isolated from the rest of the board power supplies. Special
care must be taken to minimize noise when providing board level power to these output buffers. The power supply
can be 1.5 V or 1.8 V depending on the end application.
RX input buffers.
The power supplies to the RX input buffers should be isolated from the rest of the board power supplies. Special
care must be taken to minimize noise when providing board level power to these input buffers. The power supply
can be 1.5 V or 1.8 V depending on the end application.
Recommended Power Supply Filtering Scheme
The board connections of the various SERDES VDD and VSS pins are critical to system performance. An example
demonstration board schematic is available at:
http://www.latticesemi.com
Power supply ltering is in the form of:
A parallel bypass capacitor network consisting of 10 f, 0.1 f, and 1.0 f caps close to the power source.
A parallel bypass capacitor network consisting of 0.01 f and 0.1 f close to the pin on the ORSO82G5.
Example connections are shown in
Figure 49. The naming convention for the power supply sources shown in the
gure are as follows:
Supply_1.5 V—TX-RX digital, auxiliary power pins.
Supply_VDDRX—RX analog power pins, guard band power pins.
Supply VDDTX—TX analog power pins.
Supply VDDIB—Input RX buffer power pins.
Supply_VDDOB—Output TX buffer power pins.