Voltage Regulation - Xilinx Virtex-4 RocketIO User Manual

Chapter 6: Analog and Board Design Considerations
Although not the preferred implementation, the transmitter and receiver can also be
externally AC-coupled. When externally AC-coupled, V
substantially different from each other without changing the current draw.

Voltage Regulation

The MGT voltage regulator circuits must be isolated from other supplies (including FPGA
supplies V
power supplies of the same voltage; however, each supply pin must still have its own
separate passive-filtering network as shown in
must be used.
V IN
IN
+
10µF
GND
166
Transmitter
I / 2
TTX[MAX]
TX
I
TTX
Figure 6-2: Internal Receiver AC Coupling with External DC Coupling between
Transmitter and Receiver Terminations
Note:
Placing a Virtex-4 RocketIO MGT in power-down mode does not disconnect the
termination network; current draw from the V
open-circuit current draw from the RocketIO MGT requires the serial data input and output lines
to be completely disconnected from any circuits.
V Current Consumption when DC-coupled to a receiver with internal AC coupling
TTX
and V = V :
TRX TTX
[(2M + T) x I
TTX[MAX]
V Current Consumption when DC-coupled to a receiver with internal AC coupling
TRX
and V = V :
TRX TTX
[R x I /2] + [I
TTX[MAX]
V Current Consumption when externally AC-coupled to a receiver:
TTX
[(2M + T) x I
TTX[MAX]
V Current Consumption when externally AC-coupled to a transmitter:
TRX
[2M x I
TRX[OPEN_CIRCUIT]
, V , and V
CCINT CCO
OUT
+
330µF
GND
Figure 6-3: Power Supply Circuit
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V V
TTX TRX
R R R
/ 2 I
TRX
and V
TRX
/2] + [I
TTX[OPEN_CIRCUIT]
x (2N – R)]
TRX[OPEN_CIRCUIT]
+ [I x (2Z + T)]
TTX[OPEN_CIRCUIT]
). Voltage regulators can be shared among MGT
CCAUX
Figure
1µF 1µF 1µF 1µF 1µF
Receiver
R = 50Ω
RX
/ 2
UG076_ch6_11_092506
pins continues to occur. Achieving
TTX
x (2Z + T)] Equation 6-4
Equation 6-5
and V might be
TTX TRX
Equation 6-6
Equation 6-7
6-4. The regulator filtering network
V @1.5A
OUT
1µF 1µF 1µF
GND
UG024_026_091506
Virtex-4 RocketIO MGT User Guide
UG076 (v4.1) November 2, 2008
R