7I47 6
OPERATION
5V POWER
The 7I46 being passive requires no 5V power for operation, the SPI channels
however may draw up to 500 mA of current per channel. This power will normally be
supplied via TB1. For testing and with low power SPI devices, the SPI connectors can get
their power from the controller cable
If W1 is on the "UP" position, the controller cable will supply the SPI connector
power and T1 can remain unconnected. This mode can be used for testing but it is
suggested that W1 be placed in the "DOWN" position and SPI power be supplied via TB1
for most applications.
The power from connector TB1 Passes through a 3.75A PTC device before being
routed to the I/O terminals. This limits the total I/O power supplied by the 7I46 to ~3 A in
0 to 70C ambients.
Note that the 5V power supplied to the SPI connectors via TB1 is switched by a high
side switch that disconnect the SPI devices power when cable power is lost. This is done
to prevent back-powering the FPGA card from SPI outputs when the FPGA card is
powered down.
