May 5th, 2008
Fan Temperature Control
Temperature is controlled by regulating the fan speed of the fan. In user mode, the user has control over the speed of the fan via 2 trimpots (right side of Fig. 1) that directly adjusts the fan supply voltage from ~7-12V. In autonomous mode, Fan 1 is controlled by voltage regulation with a 4-bit R-2R DAC that is optoisolated from the fan motors. An enable pin switches the fan on/off with a TIP31A NPN transistor.
