DO-CPLD-DK-J-G Xilinx Inc, DO-CPLD-DK-J-G Datasheet - Page 21

• Manufacturer Part Number: DO-CPLD-DK-J-G
• Description: KIT STARTER CPLD JAPANESE
• Manufacturer: Xilinx Inc
• Series: CoolRunner™- IIr
• Type: CPLD Development Kitr

Specifications of DO-CPLD-DK-J-G

• Contents: Proto Board, Download Cable, Software and Documentation
• For Use With/related Products: CoolRunner-ll, XC9500XL
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CPLD I/O User Guide
UG445 (v1.1) November 27, 2007
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Driving 5V with a CPLD
First, determine if 5V is truly necessary for the downstream device. LVTTL, a 5V standard,
can be driven by a LVCMOS33 device and function properly. This is because the input
thresholds for the 5V device are met by the output thresholds for the LVCMOS33 I/O
standard. The information below applies if you still need 5V outputs.
CoolRunner-II devices are not 5V-tolerant.
For other CPLDs, the basic strategy is to configure the I/O structure so that it drives either
a 0, or is high-Z. Then, use an external pull-up resistor (.5K to 1K) to 5V. To do this, run the
output signal logic to the enable of the OBUFT. The logic input of the OBUFT is connected
to ground. In this way, when the signal is low, the output is grounded.
When the signal is high, the output is placed in a Tristate condition, and the external
pull-up will pull the output up to 5V.
The following expands upon the first solution. Using a feedback loop will allow the output
to drive up to 3.3V (or 2.5V) for a short period of time before being placed in a Tristate
condition and allowing the external pull-up resistor take care of the rest. The advantage of
this is that it has a faster rise, from 0 to 3.3V (or 2.5V), than the first solution.
Oxide Lifetime for 65Å gate oxide is ~2.66 years at 5.0V
Oxide Lifetime for 65Å gate oxide is ~0.24 years at 5.5V
Oxide Lifetime for 65Å gate oxide is ~10 minutes at 7.5V
Figure 7: Fast Rise Time Method of Driving 5V
Figure 6:
www.xilinx.com
Simplified Method of Driving 5V
Power, Sequencing, and Slew Rates
UG445_05_052207
UG445_06_052207
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