[Figure 1, near callout 33]
The ZCU670 uses the Infineon MAX6643 (U50) fan controller, which autonomously controls the fan speed by controlling the pulse width modulation (PWM) signal to the fan based on the die temperature sensed via the FPGA's DXP and DXN pins. The fan rotates slowly (acoustically quiet) when the RFSoC is cool and rotates faster as the FPGA heats up (acoustically noisy). The fan speed (PWM) versus the RFSoC die temperature algorithm along with the over temperature set point and fan failure alarm mechanisms are defined by the strapping resistors on the MAX6643 device. The over temperature and fan failures alarms can be monitored by any available processor in the RFSoC by polling the I2C expander U15 on the I2C0 bus. See the MAX6643 data sheet on the Maxim Integrated Circuits website for more information on the device circuit implementation on this board.
The ZCU670 cooling fan circuit is shown in the following figure.
