USB Powering

On Experimental Boards 1.2 and 1.3 and Power Supply Modules 1.1 FPGA Boards can be easily supplied by USB by connecting pins B2 and and A1 on the Experimental Board I/O connector or by connecting pins A1, B2, C1, D1 on the FPGA Board I/O connector.

If devices are powered by USB is must be ensured that the power requirement is within the USB specifications. USB standard guarntees 0.5W and allows up to 2.5W.

DDR SDRAM on USB-FPGA Modules 1.11 requires about 1.8W and DDR2 SDRAM on USB-FPGA Modules 1.15 about 1.4W at maximum frequency. A lot of power can be saved by reducing memory clock frequency and by turning off the parallel termination. E.g. at a memory frequency of 133 MHz the bandwidth is still 532 MByte/s which is sufficient for the most applications.