--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Jerome,
>
> I don't know what could be blowing those FETS.  As you see those are rated for 30V 3.7A cont 15A peak and you are only driving then with 12V @ ~ 0.2A.
>
> But I can't see where you specify the model number you are using.  The serial number doesn't help identify the device.
>
> Those coils should be more than 12V/0.2A = 60 ohms.  I think you could check for the presence of a diode with an ohmmeter.
>
> Regards
> TK
>
>
>
> ________________________________
> From: Fouijar <fouijar@...>
> To: DynoMotion@yahoogroups.com
> Sent: Thursday, May 10, 2012 5:46 PM
> Subject: [DynoMotion] Re: Mosfet NDS9956A
>
>
>  
> Hi Tom, Lee,
>
> Here's the link of the product's datasheet:
> http://gfinder.findernet.com//assets/Series/41/S55EN.pdf
>
> The Serial number is : 553390120040 (12V) (p.3) + protection module (p.9).
>
> The wiring is made according to the datasheet.
>
> I plan to use Optocoupled EMR relays to command the 3 phased relays, I already use this type of relay with the opto outs of Kanalog with great success. The brand is the same but the relays are used as interface modules:
> http://gfinder.findernet.com//assets/Series/47/S38EN.pdf
>
> If I understand, you suggest a kind of "Darlington pair"?
>
> I'll try to find if I have a picture.
>
> Thanks to remote control... I found one, lies in my folder.
>
> Regards,
>
> Jerome
>
> --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> >
> >
> > Hi Jerome,
> > Just replacing the fets might not solve your issue:
> >
> > Could you post a drawing of your relay wiring to the files section.
> > information needed:
> > What **DC* voltage are you using for driving the relay coils?
> > What relay coil ohms/voltage?
> > What Flyback diodes and part number?
> >
> > There has to be a reason why the 'power'(VA) used exceeded for the NDS9956A mosfets operating range. There's a SOA Figure 14. Maximum Safe Operating Area in the datasheet for that part. If your relays are large and needed >= 24VDC, you may need an intermediary relay or
> > a slaved device like either: a cascoded( spelling is correct) larger Nch device, or a larger P-channel device to pull the relay to a positive DC rail.
> > I can give you some examples, but need to know your voltages and currents being switched for the relays and loads.
> >
> > -Lee
> >
> >
> >
> > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > >
> > > Hi Tom,
> > >
> > >
> > > I currently have the SW2, SW6 and SW7 outputs burned.
> > > The SW2 died very soon after using the board, without any reason.
> > > About the SW6, 7 it's something else.
> > > I use them to drive a couple of relays with fly back diodes but I think the protection isn't working very well. This is not normal since it's coming from a major industrial manufacturer of automation c
> > > The end of the full story:
> > > I was finishing my M6 program, I mean tuning the code to handle things securely. I wrote the last line and tested... first time OK!
> > > A second one to check the tooling choice sequence in the opposite d
> > >
> >
>

--- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@...> wrote:
>
> Hi Tom,
>
> I made a mistake, the coils aren't 12V any more, I changed the relays to have 24V for every control system. Initially I had both 12 and 24V.
> On page 5, the value of the coil R=600 ohms.
>
> Maybe "breaking extra-current", for cars ignition coils it's about 20 times the nominal value. Difficult to model without good measures (ok, maybe Lenz's law).
>
> I mentioned the number in my answer to Lee (#553390120040).
> Correct # is: 553390240040
> The serial number gives;
> the model: 55.33
> DC coil version:9
> coil operating voltage: 024V (0040, not useful for this situation).
>
> I already ordered 10 pieces from HK, more tests will tell us what's going on. Now I'll use Opto-out / opto-in controls.
>
> Regards,
>
> J
>
> --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> >
> > Hi Jerome,
> >
> > I don't know what could be blowing those FETS.  As you see those are rated for 30V 3.7A cont 15A peak and you are only driving then with 12V @ ~ 0.2A.
> >
> > But I can't see where you specify the model number you are using.  The serial number doesn't help identify the device.
> >
> > Those coils should be more than 12V/0.2A = 60 ohms.  I think you could check for the presence of a diode with an ohmmeter.
> >
> > Regards
> > TK
> >
> >
> >
> > ________________________________
> > From: Fouijar <fouijar@>
> > To: DynoMotion@yahoogroups.com
> > Sent: Thursday, May 10, 2012 5:46 PM
> > Subject: [DynoMotion] Re: Mosfet NDS9956A
> >
> >
> >  
> > Hi Tom, Lee,
> >
> > Here's the link of the product's datasheet:
> > http://gfinder.findernet.com//assets/Series/41/S55EN.pdf
> >
> > The Serial number is : 553390120040 (12V) (p.3) + protection module (p.9).
> >
> > The wiring is made according to the datasheet.
> >
> > I plan to use Optocoupled EMR relays to command the 3 phased relays, I already use this type of relay with the opto outs of Kanalog with great success. The brand is the same but the relays are used as interface modules:
> > http://gfinder.findernet.com//assets/Series/47/S38EN.pdf
> >
> > If I understand, you suggest a kind of "Darlington pair"?
> >
> > I'll try to find if I have a picture.
> >
> > Thanks to remote control... I found one, lies in my folder.
> >
> > Regards,
> >
> > Jerome
> >
> > --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> > >
> > >
> > > Hi Jerome,
> > > Just replacing the fets might not solve your issue:
> > >
> > > Could you post a drawing of your relay wiring to the files section.
> > > information needed:
> > > What **DC* voltage are you using for driving the relay coils?
> > > What relay coil ohms/voltage?
> > > What Flyback diodes and part number?
> > >
> > > There has to be a reason why the 'power'(VA) used exceeded for the NDS9956A mosfets operating range. There's a SOA Figure 14. Maximum Safe Operating Area in the datasheet for that part. If your relays are large and needed >= 24VDC, you may need an intermediary relay or
> > > a slaved device like either: a cascoded( spelling is correct) larger Nch device, or a larger P-channel device to pull the relay to a positive DC rail.
> > > I can give you some examples, but need to know your voltages and currents being switched for the relays and loads.
> > >
> > > -Lee
> > >
> > >
> > >
> > > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > > >
> > > > Hi Tom,
> > > >
> > > >
> > > > I currently have the SW2, SW6 and SW7 outputs burned.
> > > > The SW2 died very soon after using the board, without any reason.
> > > > About the SW6, 7 it's something else.
> > > > I use them to drive a couple of relays with fly back diodes but I think the protection isn't working very well. This is not normal since it's coming from a major industrial manufacturer of automation c
> > > > The end of the full story:
> > > > I was finishing my M6 program, I mean tuning the code to handle things securely. I wrote the last line and tested... first time OK!
> > > > A second one to check the tooling choice sequence in the opposite d
> > > >
> > >
> >
>

--- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@...> wrote:
>
> Hi Jerome,
> I was looking over the datasheets and I agree with Tom that the diode
> is suspect. Verify that the diode isn't popped-shorted, and cathode is pointing toward the 24vdc rail. So A1/13 is connected to the 24vdc rail, and A2/14 to the mosfet (sw to ground ). Another thing might be to add a diode across the mosfet( cathode toward the positive ) to protect against the drain bucking negative.
>
> The dissapation goal is to never let the mosfet see over 30vdc( even if inductive coil spike), and that it never has to dissipate more then about 1 watt over more than seconds or minutes( unless there's alot of copper around the device )
>
> The Cascode arrangement is similar, but not a gain like darlington. It allows the the lower mosfet operate well within it's SOA at a lower voltage. The upper device has its gate fixed to something like 5vdc( or 12vdc etc) and its source is switched to ground by the lower device. The lower device still has to handle the current, but now at a lower voltage Drain to source allowing less power dissapation. The upper device should be rated to handle the higher voltages.
> By a really bizarre coincidence, this guy wrote it up well today! I learned of it years ago from a switching power supply guru.
> http://electronicdesign.com/article/power/cascode-technology-enables-faster-switching-fequencies-losses-73901
>
>
> --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> >
> > Hi Tom,
> >
> > I made a mistake, the coils aren't 12V any more, I changed the relays to have 24V for every control system. Initially I had both 12 and 24V.
> > On page 5, the value of the coil R=600 ohms.
> >
> > Maybe "breaking extra-current", for cars ignition coils it's about 20 times the nominal value. Difficult to model without good measures (ok, maybe Lenz's law).
> >
> > I mentioned the number in my answer to Lee (#553390120040).
> > Correct # is: 553390240040
> > The serial number gives;
> > the model: 55.33
> > DC coil version:9
> > coil operating voltage: 024V (0040, not useful for this situation).
> >
> > I already ordered 10 pieces from HK, more tests will tell us what's going on. Now I'll use Opto-out / opto-in controls.
> >
> > Regards,
> >
> > J
> >
> > --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> > >
> > > Hi Jerome,
> > >
> > > I don't know what could be blowing those FETS.  As you see those are rated for 30V 3.7A cont 15A peak and you are only driving then with 12V @ ~ 0.2A.
> > >
> > > But I can't see where you specify the model number you are using.  The serial number doesn't help identify the device.
> > >
> > > Those coils should be more than 12V/0.2A = 60 ohms.  I think you could check for the presence of a diode with an ohmmeter.
> > >
> > > Regards
> > > TK
> > >
> > >
> > >
> > > ________________________________
> > > From: Fouijar <fouijar@>
> > > To: DynoMotion@yahoogroups.com
> > > Sent: Thursday, May 10, 2012 5:46 PM
> > > Subject: [DynoMotion] Re: Mosfet NDS9956A
> > >
> > >
> > >  
> > > Hi Tom, Lee,
> > >
> > > Here's the link of the product's datasheet:
> > > http://gfinder.findernet.com//assets/Series/41/S55EN.pdf
> > >
> > > The Serial number is : 553390120040 (12V) (p.3) + protection module (p.9).
> > >
> > > The wiring is made according to the datasheet.
> > >
> > > I plan to use Optocoupled EMR relays to command the 3 phased relays, I already use this type of relay with the opto outs of Kanalog with great success. The brand is the same but the relays are used as interface modules:
> > > http://gfinder.findernet.com//assets/Series/47/S38EN.pdf
> > >
> > > If I understand, you suggest a kind of "Darlington pair"?
> > >
> > > I'll try to find if I have a picture.
> > >
> > > Thanks to remote control... I found one, lies in my folder.
> > >
> > > Regards,
> > >
> > > Jerome
> > >
> > > --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> > > >
> > > >
> > > > Hi Jerome,
> > > > Just replacing the fets might not solve your issue:
> > > >
> > > > Could you post a drawing of your relay wiring to the files section.
> > > > information needed:
> > > > What **DC* voltage are you using for driving the relay coils?
> > > > What relay coil ohms/voltage?
> > > > What Flyback diodes and part number?
> > > >
> > > > There has to be a reason why the 'power'(VA) used exceeded for the NDS9956A mosfets operating range. There's a SOA Figure 14. Maximum Safe Operating Area in the datasheet for that part. If your relays are large and needed >= 24VDC, you may need an intermediary relay or
> > > > a slaved device like either: a cascoded( spelling is correct) larger Nch device, or a larger P-channel device to pull the relay to a positive DC rail.
> > > > I can give you some examples, but need to know your voltages and currents being switched for the relays and loads.
> > > >
> > > > -Lee
> > > >
> > > >
> > > >
> > > > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > > > >
> > > > > Hi Tom,
> > > > >
> > > > >
> > > > > I currently have the SW2, SW6 and SW7 outputs burned.
> > > > > The SW2 died very soon after using the board, without any reason.
> > > > > About the SW6, 7 it's something else.
> > > > > I use them to drive a couple of relays with fly back diodes but I think the protection isn't working very well. This is not normal since it's coming from a major industrial manufacturer of automation c
> > > > > The end of the full story:
> > > > > I was finishing my M6 program, I mean tuning the code to handle things securely. I wrote the last line and tested... first time OK!
> > > > > A second one to check the tooling choice sequence in the opposite d
> > > > >
> > > >
> > >
> >
>

--- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@...> wrote:
>
> Also when I mean the mosfet dissipation, it's the (Rds * Id^2)
> or the Vds * Ids that is being forced by the load condition. If the load current is causing the Rds to rise to a significant voltage, the SOA graph becomes critical over the time span this is occurring. This could occur if there was a overly large cap across the coil for example. Clear as mud huh :-)
>
> --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> >
> > Hi Jerome,
> > I was looking over the datasheets and I agree with Tom that the diode
> > is suspect. Verify that the diode isn't popped-shorted, and cathode is pointing toward the 24vdc rail. So A1/13 is connected to the 24vdc rail, and A2/14 to the mosfet (sw to ground ). Another thing might be to add a diode across the mosfet( cathode toward the positive ) to protect against the drain bucking negative.
> >
> > The dissapation goal is to never let the mosfet see over 30vdc( even if inductive coil spike), and that it never has to dissipate more then about 1 watt over more than seconds or minutes( unless there's alot of copper around the device )
> >
> > The Cascode arrangement is similar, but not a gain like darlington. It allows the the lower mosfet operate well within it's SOA at a lower voltage. The upper device has its gate fixed to something like 5vdc( or 12vdc etc) and its source is switched to ground by the lower device. The lower device still has to handle the current, but now at a lower voltage Drain to source allowing less power dissapation. The upper device should be rated to handle the higher voltages.
> > By a really bizarre coincidence, this guy wrote it up well today! I learned of it years ago from a switching power supply guru.
> > http://electronicdesign.com/article/power/cascode-technology-enables-faster-switching-fequencies-losses-73901
> >
> >
> > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > >
> > > Hi Tom,
> > >
> > > I made a mistake, the coils aren't 12V any more, I changed the relays to have 24V for every control system. Initially I had both 12 and 24V.
> > > On page 5, the value of the coil R=600 ohms.
> > >
> > > Maybe "breaking extra-current", for cars ignition coils it's about 20 times the nominal value. Difficult to model without good measures (ok, maybe Lenz's law).
> > >
> > > I mentioned the number in my answer to Lee (#553390120040).
> > > Correct # is: 553390240040
> > > The serial number gives;
> > > the model: 55.33
> > > DC coil version:9
> > > coil operating voltage: 024V (0040, not useful for this situation).
> > >
> > > I already ordered 10 pieces from HK, more tests will tell us what's going on. Now I'll use Opto-out / opto-in controls.
> > >
> > > Regards,
> > >
> > > J
> > >
> > > --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> > > >
> > > > Hi Jerome,
> > > >
> > > > I don't know what could be blowing those FETS.  As you see those are rated for 30V 3.7A cont 15A peak and you are only driving then with 12V @ ~ 0.2A.
> > > >
> > > > But I can't see where you specify the model number you are using.  The serial number doesn't help identify the device.
> > > >
> > > > Those coils should be more than 12V/0.2A = 60 ohms.  I think you could check for the presence of a diode with an ohmmeter.
> > > >
> > > > Regards
> > > > TK
> > > >
> > > >
> > > >
> > > > ________________________________
> > > > From: Fouijar <fouijar@>
> > > > To: DynoMotion@yahoogroups.com
> > > > Sent: Thursday, May 10, 2012 5:46 PM
> > > > Subject: [DynoMotion] Re: Mosfet NDS9956A
> > > >
> > > >
> > > >  
> > > > Hi Tom, Lee,
> > > >
> > > > Here's the link of the product's datasheet:
> > > > http://gfinder.findernet.com//assets/Series/41/S55EN.pdf
> > > >
> > > > The Serial number is : 553390120040 (12V) (p.3) + protection module (p.9).
> > > >
> > > > The wiring is made according to the datasheet.
> > > >
> > > > I plan to use Optocoupled EMR relays to command the 3 phased relays, I already use this type of relay with the opto outs of Kanalog with great success. The brand is the same but the relays are used as interface modules:
> > > > http://gfinder.findernet.com//assets/Series/47/S38EN.pdf
> > > >
> > > > If I understand, you suggest a kind of "Darlington pair"?
> > > >
> > > > I'll try to find if I have a picture.
> > > >
> > > > Thanks to remote control... I found one, lies in my folder.
> > > >
> > > > Regards,
> > > >
> > > > Jerome
> > > >
> > > > --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> > > > >
> > > > >
> > > > > Hi Jerome,
> > > > > Just replacing the fets might not solve your issue:
> > > > >
> > > > > Could you post a drawing of your relay wiring to the files section.
> > > > > information needed:
> > > > > What **DC* voltage are you using for driving the relay coils?
> > > > > What relay coil ohms/voltage?
> > > > > What Flyback diodes and part number?
> > > > >
> > > > > There has to be a reason why the 'power'(VA) used exceeded for the NDS9956A mosfets operating range. There's a SOA Figure 14. Maximum Safe Operating Area in the datasheet for that part. If your relays are large and needed >= 24VDC, you may need an intermediary relay or
> > > > > a slaved device like either: a cascoded( spelling is correct) larger Nch device, or a larger P-channel device to pull the relay to a positive DC rail.
> > > > > I can give you some examples, but need to know your voltages and currents being switched for the relays and loads.
> > > > >
> > > > > -Lee
> > > > >
> > > > >
> > > > >
> > > > > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > > > > >
> > > > > > Hi Tom,
> > > > > >
> > > > > >
> > > > > > I currently have the SW2, SW6 and SW7 outputs burned.
> > > > > > The SW2 died very soon after using the board, without any reason.
> > > > > > About the SW6, 7 it's something else.
> > > > > > I use them to drive a couple of relays with fly back diodes but I think the protection isn't working very well. This is not normal since it's coming from a major industrial manufacturer of automation c
> > > > > > The end of the full story:
> > > > > > I was finishing my M6 program, I mean tuning the code to handle things securely. I wrote the last line and tested... first time OK!
> > > > > > A second one to check the tooling choice sequence in the opposite d
> > > > > >
> > > > >
> > > >
> > >
> >
>

--- In DynoMotion@yahoogroups.com, Martin <martin.reynolds@...> wrote:
>
> This all sounds like a bad flyback diode. You must have a snubber across
> any relay coil, as otherwise your drivers will see a big voltage spike.
> Double check that wiring with a meter.
>
> The other possibility - too high a dI/dT - only happens with capacitor and
> filament loads. Those you fix with a tiny cap on the gate to slow the rise
> time.
>
> On Fri, May 11, 2012 at 12:51 PM, studleylee <indigo_red@...> wrote:
>
> > **
> >
> >
> > Also when I mean the mosfet dissipation, it's the (Rds * Id^2)
> > or the Vds * Ids that is being forced by the load condition. If the load
> > current is causing the Rds to rise to a significant voltage, the SOA graph
> > becomes critical over the time span this is occurring. This could occur if
> > there was a overly large cap across the coil for example. Clear as mud huh
> > :-)
> >
> >
> > --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> > >
> > > Hi Jerome,
> > > I was looking over the datasheets and I agree with Tom that the diode
> > > is suspect. Verify that the diode isn't popped-shorted, and cathode is
> > pointing toward the 24vdc rail. So A1/13 is connected to the 24vdc rail,
> > and A2/14 to the mosfet (sw to ground ). Another thing might be to add a
> > diode across the mosfet( cathode toward the positive ) to protect against
> > the drain bucking negative.
> > >
> > > The dissapation goal is to never let the mosfet see over 30vdc( even if
> > inductive coil spike), and that it never has to dissipate more then about 1
> > watt over more than seconds or minutes( unless there's alot of copper
> > around the device )
> > >
> > > The Cascode arrangement is similar, but not a gain like darlington. It
> > allows the the lower mosfet operate well within it's SOA at a lower
> > voltage. The upper device has its gate fixed to something like 5vdc( or
> > 12vdc etc) and its source is switched to ground by the lower device. The
> > lower device still has to handle the current, but now at a lower voltage
> > Drain to source allowing less power dissapation. The upper device should be
> > rated to handle the higher voltages.
> > > By a really bizarre coincidence, this guy wrote it up well today! I
> > learned of it years ago from a switching power supply guru.
> > >
> > http://electronicdesign.com/article/power/cascode-technology-enables-faster-switching-fequencies-losses-73901
> > >
> > >
> > > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > > >
> > > > Hi Tom,
> > > >
> > > > I made a mistake, the coils aren't 12V any more, I changed the relays
> > to have 24V for every control system. Initially I had both 12 and 24V.
> > > > On page 5, the value of the coil R=600 ohms.
> > > >
> > > > Maybe "breaking extra-current", for cars ignition coils it's about 20
> > times the nominal value. Difficult to model without good measures (ok,
> > maybe Lenz's law).
> > > >
> > > > I mentioned the number in my answer to Lee (#553390120040).
> > > > Correct # is: 553390240040
> > > > The serial number gives;
> > > > the model: 55.33
> > > > DC coil version:9
> > > > coil operating voltage: 024V (0040, not useful for this situation).
> > > >
> > > > I already ordered 10 pieces from HK, more tests will tell us what's
> > going on. Now I'll use Opto-out / opto-in controls.
> > > >
> > > > Regards,
> > > >
> > > > J
> > > >
> > > > --- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@> wrote:
> > > > >
> > > > > Hi Jerome,
> > > > >
> > > > > I don't know what could be blowing those FETS. As you see those
> > are rated for 30V 3.7A cont 15A peak and you are only driving then with 12V
> > @ ~ 0.2A.
> > > > >
> > > > > But I can't see where you specify the model number you are using.Â
> > The serial number doesn't help identify the device.
> > > > >
> > > > > Those coils should be more than 12V/0.2A = 60 ohms. I think you
> > could check for the presence of a diode with an ohmmeter.
> > > > >
> > > > > Regards
> > > > > TK
> > > > >
> > > > >
> > > > >
> > > > > ________________________________
> > > > > From: Fouijar <fouijar@>
> > > > > To: DynoMotion@yahoogroups.com
> > > > > Sent: Thursday, May 10, 2012 5:46 PM
> > > > > Subject: [DynoMotion] Re: Mosfet NDS9956A
> > > > >
> > > > >
> > > > > Â
> > > > > Hi Tom, Lee,
> > > > >
> > > > > Here's the link of the product's datasheet:
> > > > > http://gfinder.findernet.com//assets/Series/41/S55EN.pdf
> > > > >
> > > > > The Serial number is : 553390120040 (12V) (p.3) + protection module
> > (p.9).
> > > > >
> > > > > The wiring is made according to the datasheet.
> > > > >
> > > > > I plan to use Optocoupled EMR relays to command the 3 phased relays,
> > I already use this type of relay with the opto outs of Kanalog with great
> > success. The brand is the same but the relays are used as interface modules:
> > > > > http://gfinder.findernet.com//assets/Series/47/S38EN.pdf
> > > > >
> > > > > If I understand, you suggest a kind of "Darlington pair"?
> > > > >
> > > > > I'll try to find if I have a picture.
> > > > >
> > > > > Thanks to remote control... I found one, lies in my folder.
> > > > >
> > > > > Regards,
> > > > >
> > > > > Jerome
> > > > >
> > > > > --- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@> wrote:
> > > > > >
> > > > > >
> > > > > > Hi Jerome,
> > > > > > Just replacing the fets might not solve your issue:
> > > > > >
> > > > > > Could you post a drawing of your relay wiring to the files section.
> > > > > > information needed:
> > > > > > What **DC* voltage are you using for driving the relay coils?
> > > > > > What relay coil ohms/voltage?
> > > > > > What Flyback diodes and part number?
> > > > > >
> > > > > > There has to be a reason why the 'power'(VA) used exceeded for the
> > NDS9956A mosfets operating range. There's a SOA Figure 14. Maximum Safe
> > Operating Area in the datasheet for that part. If your relays are large and
> > needed >= 24VDC, you may need an intermediary relay or
> > > > > > a slaved device like either: a cascoded( spelling is correct)
> > larger Nch device, or a larger P-channel device to pull the relay to a
> > positive DC rail.
> > > > > > I can give you some examples, but need to know your voltages and
> > currents being switched for the relays and loads.
> > > > > >
> > > > > > -Lee
> > > > > >
> > > > > >
> > > > > >
> > > > > > --- In DynoMotion@yahoogroups.com, "Fouijar" <fouijar@> wrote:
> > > > > > >
> > > > > > > Hi Tom,
> > > > > > >
> > > > > > >
> > > > > > > I currently have the SW2, SW6 and SW7 outputs burned.
> > > > > > > The SW2 died very soon after using the board, without any reason.
> > > > > > > About the SW6, 7 it's something else.
> > > > > > > I use them to drive a couple of relays with fly back diodes but
> > I think the protection isn't working very well. This is not normal since
> > it's coming from a major industrial manufacturer of automation c
> > > > > > > The end of the full story:
> > > > > > > I was finishing my M6 program, I mean tuning the code to handle
> > things securely. I wrote the last line and tested... first time OK!
> > > > > > > A second one to check the tooling choice sequence in the
> > opposite d
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> >
> >
>

On 5/11/2012 6:24 AM, Fouijar wrote:

 

Hi Lee,

I checked the wiring and it's right as you mentioned. I did a test diode procedure and the diode seems to be working as it should.
Your explanation isn't muddy, I understand clearly what you mean.
Anyway, sometimes things aren't working like they should. As a security measure I'll replace the diodes, I bought more than necessary diodes in prevision of such case.
I'll now check for temporary control solution, I.e. Opto outs.
Thanks for your attention and for the useful link.

Regards,

J.

--- In DynoMotion@yahoogroups.com, "studleylee" <indigo_red@...> wrote:
>
>

--- In DynoMotion@yahoogroups.com, Lee Studley <indigo_red@...> wrote:
>
> Hi Jerome,
> I simulated your setup using LTSpice and a inductor of 600ohm/24vdc and
> an estimated 1-to-4Henries.
> Wow, without a good *fast*, diode you can easily get a few Kvolts of
> inductive flyback on turnoff.
>
> I'll post a writeup in the files section on my mentioned Cascode setup.
> The article I mentioned before doesn't cover the variations. You can use
> 2 mosfets stacked instead of just a BJT.
>
> I uploaded a good Zetex appnote in the files section under"Driving
> Relays". On page 2 I added a note about the surface mount version of the
> part
> avalanche mfet ZVN4206AV that will work perfectly to complement the
> Kflop drive if a cascode is called for. Its a tough part that can take
> over-voltages nicely.
>
> -Lee
>
>
>
>
>
> On 5/11/2012 6:24 AM, Fouijar wrote:
> >
> > Hi Lee,
> >
> > I checked the wiring and it's right as you mentioned. I did a test
> > diode procedure and the diode seems to be working as it should.
> > Your explanation isn't muddy, I understand clearly what you mean.
> > Anyway, sometimes things aren't working like they should. As a
> > security measure I'll replace the diodes, I bought more than necessary
> > diodes in prevision of such case.
> > I'll now check for temporary control solution, I.e. Opto outs.
> > Thanks for your attention and for the useful link.
> >
> > Regards,
> >
> > J.
> >
> > --- In DynoMotion@yahoogroups.com
> > <mailto:DynoMotion%40yahoogroups.com>, "studleylee" <indigo_red@>
> > wrote:
> > >
> > >
> >
> >
> >
> >
>