Advantages of the Jaguars?

[Al Skierkiewicz]

Scott,
Can you disclose the type and number of Power FETs used in the Jaguar? I don't have access to one for a while during the holidays.

[s1900ahon]

Originally Posted by Al Skierkiewicz

Scott,
Can you disclose the type and number of Power FETs used in the Jaguar? I don't have access to one for a while during the holidays.

Sure can. Jaguar is a design example, so the information for it is pretty available.

3 Fairchild FDP8874 MOSFETs for each quadrant of the H-Bridge; 12 in total.

[Joe Ross]

Originally Posted by Al Skierkiewicz

Scott,
Can you disclose the type and number of Power FETs used in the Jaguar? I don't have access to one for a while during the holidays.

You can get a lot more information from Luminary Micro's Non-FIRST specific site. http://www.luminarymicro.com/products/mdl_bdc.html

[Raul]

Originally Posted by s1900ahon

AND function.

The temperature sensor monitors the ambient temperature; it isn't attached to a specific MOSFET.

Hi Scott,

Please explain precisely where the ambient temperature is being measured.

[s1900ahon]

The LM3S2616 microcontroller has an integrated temperature sensor. Each H-bridge period initiates the measurement of the motor current, the battery voltage, the ANA input value, and the temperature.

[wilsonmw04]

Originally Posted by Al Skierkiewicz

How do we turn off this feature to run the fans constantly? Once hot, a FET wants to be cooled down even if it is not passing current. And I hope this doesn't mean the fans are connected to the output of the H bridge.

Bill beat me to it.

Al, They don't turn off as soon as current is removed. In my experience, as soon as you ask the Jag to do something that fans turn on. Once you stop working the Jags, the fans stay on for a certain period of time (~ 1 minute). I'm not sure if it is time or temp dependent.

[s1900ahon]

Originally Posted by Al Skierkiewicz

How do we turn off this feature to run the fans constantly? Once hot, a FET wants to be cooled down even if it is not passing current. And I hope this doesn't mean the fans are connected to the output of the H bridge.

The fan is controlled by a separate, smaller, MOSFET; the fan is not controlled by the H-bridge.

The fan turns on whenever there is a non-zero voltage produced at the output. The fan turns off after the following three conditions are met: a) the output goes to 0 V, b) 10 seconds have passed, and c) the internal temperature is below 38C. If the temperature is not below this threshold, the fans stay on after the 10 s period.