I have to choose a Q to switch on a pump in a project. The pump draws around 5amps @ 13.8V running and 12amps stalled.
I am using a 40X2 3.3V version to control the project.
I have been using this formula here to choose the correct part and R.
http://www.kpsec.freeuk.com/trancirc.htm
I had thought to use ST micros BU941ZT.
http://www.st.com/stonline/books/pdf/docs/5288.pdf
I am having trouble understanding if it is possible to use this part in my app due to the figure I am getting using the formula contained in the Q info web site.
Applying the formula it seems a I need a Q with hFE >3750 ie. 5X 15000/20=3750
The BU941ZT data sheet states the part has a min. hFE of 300.
Any advice welcome guys.
I am using a 40X2 3.3V version to control the project.
I have been using this formula here to choose the correct part and R.
http://www.kpsec.freeuk.com/trancirc.htm
I had thought to use ST micros BU941ZT.
http://www.st.com/stonline/books/pdf/docs/5288.pdf
I am having trouble understanding if it is possible to use this part in my app due to the figure I am getting using the formula contained in the Q info web site.
Applying the formula it seems a I need a Q with hFE >3750 ie. 5X 15000/20=3750
The BU941ZT data sheet states the part has a min. hFE of 300.
Any advice welcome guys.