I/O Weightings for the LX150T-FG(G)676 and LX75T-FG(G)676
The maximum number of I/O that can be used in each bank are most strongly influenced by the voltage of the I/O standard used. This section is broken up between 3.3V standards and 2.5V and less standards.
For I/O standards operating at or below 2.5V, the weights in the table below can be used to calculate the maximum number of each type of I/O that can be used in banks 0 when MGTs 101 or 123 are used or bank 2 when MGTs 245 or 267 are used. Multiplying the number of I/O in each category by its weight then adding them together cannot exceed 80 in banks adjacent to GTP Transceivers used in the design.
I/O Category Weight
Single Ended Output 4
Single Ended Input 2
Differential Input/Output Pins 1
For 3.3V I/O standards, guidelines for banks 0 and 2 can be found below and utilize the same 80 point maximum. For 3.3V Strong outputs (>4mA), a maximum of 100 pins can be used in the side banks, banks 1, 3, 4 and 5 (these banks have no limits for weak 3.3V or less I/O other than the SSO limits in the Spartan-6 FPGA Data Sheet (DS162).
Bank0:
I/O Category Weight
Single Ended Strong Output (>4mA) Not Permitted
Single Ended Weak Output (4mA) 16
Single Ended Strong Input (>4mA) Not Permitted
Single Ended Weak Inputs (4mA) 8
Bank2:
I/O Category Weight
Single Ended Strong Output (>4mA) 4
Single Ended Weak Output (4mA) 3.2
Single Ended Strong Input (>4mA) 2
Single Ended Weak Inputs (4mA) 1.6
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