Xilinx Virtex-4 ML461 User Manual page 40

Chapter 4: Electrical Requirements
Table 4-2
Table 4-2: Power Planes
Each of the three Fairchild ML6554 Bus Terminator Regulators has two voltage outputs:
one each for V
the V
Because the V
power supply does not source any real current. Thus the 3 mA capacity for the V
is considered sufficient.
The V
regulator. The minimum driver output voltage swing around V
SSTL18, SSTL2, and HSTL I/O standards as:
•
•
•
For a given memory interface, the maximum number of single-ended (non-differential)
signals that might need to be pulled up or down at a time for QDR II is 144 data bits and
approximately 30 address and control signals. The differential pair signals offset for the
sink and source of current. With a continuous current capacity of 3A for the ML6554
regulator, the regulator can supply up to (3000 / 175) = 17 mA of current per signal. The
maximum drive strength for a driver is specified at 16 mA. For a 50Ω V
current can support a voltage swing of up to (16 mA * 50Ω) = 800 mV, which is sufficient to
meet the output voltage specifications for SSTL18, SSTL2, and HSTL18 I/O standards.
Table 4-3
TI power modules for the first set of six power planes and the three Fairchild regulators for
the V
that each of the nine modules can supply the necessary power for the corresponding
power plane.
40
lists the 12 different power planes on the Virtex-4 ML461 Development Board.
Power
+1.2V
+1.8V for SSTL18
+1.8V for HSTL18
+2.5V
+2.6V
+3.3V
+0.9V for SSTL18 V
REF
+0.9V for SSTL18 V
TT
+0.9V for HSTL18 V
REF
+0.9V for HSTL18 V
TT
+1.3V for SSTL2 V
REF
+1.3V for SSTL2 V
TT
and V
REF TT
output and 3 mA for the V
TT
voltage is used by the FPGA and memory devices only as reference, the
REF
voltage is guaranteed to within ± 20 mV of the V
TT
SSTL2: ± 608 mV
SSTL18: ± 603 mV
HSTL: ± 500 mV (for HSTL18)
separates the power consumption information from
power planes. The positive values in the Excess Power column of
TT
www.xilinx.com
Texas Instruments PTH05010WAS Modules
Three Fairchild ML6554 Bus Terminator Regulators
. The ML6554 regulator is a push-pull device rated at ± 3A for
output.
REF
Virtex-4 ML461 Development Board User Guide
Power Source
REF
output by the ML6554
REF
is specified for the
REF
termination, this
TT
Table 4-1 according to the six
Table 4-3
UG079 (v1.1) September 5, 2007
R
output
show