Pcb Design Requirements; Power Conditioning; Voltage Regulation - Xilinx RocketIO User Manual

PCB Design Requirements

For further clarity, TXUSRCLK is used to clock data from the FPGA core to the TX FIFO. The
FIFO depth accounts for the slight phase difference between these two clocks. If the clocks are
locked in frequency, then the FIFO acts much like a pass-through buffer.
PCB Design Requirements
To ensure reliable operation of the RocketIO transceivers, certain requirements must be met by the
designer. This section outlines these requirements governing power filtering networks, high-speed
differential signal traces, and reference clocks. Any designs that do not adhere to these requirements
will not be supported by Xilinx, Inc.

Power Conditioning

Each RocketIO transceiver has five power supply pins, all of which are sensitive to noise.
summarizes the power supply pins, their names, associated voltages, and power requirements.
To operate properly, the RocketIO transceiver requires a certain level of noise isolation from
surrounding noise sources. For this reason, it is required that both dedicated voltage regulators and
passive high-frequency filtering be used to power the RocketIO circuitry.
Table 3-5: Transceiver Power Supplies

Voltage Regulation

The transceiver voltage regulator circuits must not be shared with any other supplies (including
FPGA supplies V
transceiver power supplies of the same voltage; however, each supply pin must still have its own
separate passive filtering network. (See
RocketIO™ Transceiver User Guide
UG024 (v2.3.2) June 24, 2004
Supply 2.5V
√
AVCCAUXRX
√
AVCCAUXTX
(2)
VTRX
VTTX
GNDA
Notes:
1. Power at max data rate. Power figures shown do not include power requirements of V
(48 mW), which power the PCS and PMA respectively.
2. See section "AC and DC Coupling," page
cases.
3. These numbers are based on VTTX at 2.5V for the DC- and AC-coupled cases; VTRX at 2.5V for the DC-coupled case,
and 1.8V for the AC-coupled case.
, V
CCINT CCO
Power
1.8V - 1.5V -
DC
2.625V 1.8V
Coupled
90
130
(3)
√ √
37.5
(3)
√
37.5
N/A
114, and Table 3-7 for VTRX supply restrictions in AC- and DC-coupled
, V , and V ). Voltage regulators may be shared among
CCAUX REF
Figure 3-7.)
www.xilinx.com
1-800-255-7778
(1)
(mW)
Description
AC
Coupled
90 Analog RX supply
130 Analog TX supply
(3)
0 RX termination supply
(3)
75 TX termination supply
Analog ground for transmit and
N/A
receive analog supplies
(28 mW) and V
CCINT
R
Table 3-5,
CCAUX
107