MOSFET Usage
in [Design]
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From: Ron M. on 21 May 2010 23:21 I am in the process of designing a device that uses 30A MOSFET for the output. I need it to apply a 12 Vdc source to a switchable load on the ground side. Are there any major issues using a MOSFET in this way?
From: Joe G (Home) on 22 May 2010 10:42 "Ron M." <strmbrgr2(a)hotmail.com> wrote in message news:a67274a4-1270-45cf-8c90-4f139be8ad3c(a)y12g2000vbr.googlegroups.com... >I am in the process of designing a device that uses 30A MOSFET for the > output. I need it to apply a 12 Vdc source to a switchable load on the > ground side. Are there any major issues using a MOSFET in this way? What is the load type, inductive (motor etc) capacitive, resistive? What is the peak current on switch on? Have you done thermal calcuations of the MOSFET and heat sink? What is the operating temprature range? Do the thermal calcualtions meet the MOSFET thermal requirements? What is the operating voltage? Is the max_Vds of the MOSEFT much greater than the operating voltage. What is the Vgs_turn_voltage? Is it much greater than the MOSFET Vgs_turn_on_threshold? If you answer these questions then you are well on your way to operating the MOSFET correctly. PS... good clues on MOSFET operation may be obtained from here. http://www.btipnow.com/events/training.php Joe
From: ian field on 22 May 2010 16:29 "Ron M." <strmbrgr2(a)hotmail.com> wrote in message news:a67274a4-1270-45cf-8c90-4f139be8ad3c(a)y12g2000vbr.googlegroups.com... >I am in the process of designing a device that uses 30A MOSFET for the > output. I need it to apply a 12 Vdc source to a switchable load on the > ground side. Are there any major issues using a MOSFET in this way? Make sure you examine the data sheet for "silicon limiting values" and "package limiting values" - some manufactures headline the current the die can handle but aren't so keen to draw attention to the fact the package can't match that value. There was a thread somewhere about that recently (may still be going), IR were taking a bashing as being one of the worst offenders.
From: Robert Baer on 23 May 2010 01:28 Joe G (Home) wrote: > "Ron M." <strmbrgr2(a)hotmail.com> wrote in message > news:a67274a4-1270-45cf-8c90-4f139be8ad3c(a)y12g2000vbr.googlegroups.com... >> I am in the process of designing a device that uses 30A MOSFET for the >> output. I need it to apply a 12 Vdc source to a switchable load on the >> ground side. Are there any major issues using a MOSFET in this way? > > What is the load type, inductive (motor etc) capacitive, resistive? > > What is the peak current on switch on? > > Have you done thermal calcuations of the MOSFET and heat sink? > > What is the operating temprature range? Do the thermal calcualtions meet > the MOSFET thermal requirements? > > What is the operating voltage? Is the max_Vds of the MOSEFT much greater > than the operating voltage. > > What is the Vgs_turn_voltage? Is it much greater than the MOSFET > Vgs_turn_on_threshold? > > If you answer these questions then you are well on your way to operating the > MOSFET correctly. > > PS... good clues on MOSFET operation may be obtained from here. > > http://www.btipnow.com/events/training.php > > > > > Joe > > You forgot to mention eye-squared-tee considerations.
From: Nico Coesel on 23 May 2010 04:18
"Ron M." <strmbrgr2(a)hotmail.com> wrote: >I am in the process of designing a device that uses 30A MOSFET for the >output. I need it to apply a 12 Vdc source to a switchable load on the >ground side. Are there any major issues using a MOSFET in this way? You'll probably need to divide the load over 2 or more MOSFETs due to PCB and package limits. -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico(a)nctdevpuntnl (punt=.) -------------------------------------------------------------- |