User`s manual
RTD Embedded Technologies, Inc. | www.rtd.com   24  FPGA35S6 User’s Manual 
5.5  Digital I/O 
The FPGA35S6 digital I/O on connectors CN4 and CN9 use the circuitry shown below to level shift the input voltage from 5V to 3.3V allowing 
the I/O on these connectors to be 5V tolerant. 
Figure 8: CN4/CN9 Digital I/O Circuitry 
Xilinx 
Spartan 6 
Level Shifter 
Digital I/O 
CN4/CN9 
33Ω 
10KΩ 
+5V/3.3V 










