[Figure 1, callout 34]
The VCK190 cooling fan connector is shown in the following figure. The VCK190 uses the Maxim MAX6643 (U64) 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 ACAP's DXP and DXN pins. The fan rotates slowly (acoustically quiet) when ACAP U1 is cool and rotates faster as the ACAP heats up (acoustically noisy).
The fan speed (PWM) versus the ACAP 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 either by any available processor in ACAP U1 by polling the I2C expander U233 on the I2C bus or via the ZU4 U125 System Controller.
The VCK190 board provides a fan controller bypass header J234 to permit the fan to be always on. Always on (J234 pins 2 and 3 jumpered) is the default jumper setting shown in the figure.
