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I plan to provide continuous gate drive for high side mosfet using ir2110. According to ir2110 application note, a 555 timer is used as charge pump for continuous gate drive but the schematic is hard to understand and there is little documentation. Plz explain me about this with a schematic..or is there another option for it

The application note link is http://www.irf.com/technical-info/appnotes/an-978.pdf

My project is on brush PMDC motor position control using PID. The problem I am facing is driving the high side mosfet gate continuously when required.

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  • \$\begingroup\$ Can you show us exactly which schematic is provided that is difficult to understand? \$\endgroup\$
    – nanofarad
    Commented Jul 13, 2015 at 1:41
  • \$\begingroup\$ irf.com/technical-info/appnotes/an-978.pdf \$\endgroup\$
    – Sanjok Paonam
    Commented Jul 13, 2015 at 1:45
  • \$\begingroup\$ Edit the link into your question, please. It's easier to see there. Also, what specific aspect of the schematics is difficult to understand? Knowing this will help someone provide a good answer. \$\endgroup\$
    – nanofarad
    Commented Jul 13, 2015 at 1:45

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While it is possible to do what you're trying to do, it's typically not useful for driving PMDC motors, where 100% duty cycles aren't necessary to get good performance.

The only situation in which a continuous-on high side would be useful is if you simply must have a bit of extra speed from the motor, and are unable to substitute any of the electromechanical components (the motor, transmission, etc.) to get it.

That said, TI provides a somewhat more digestible app note on the same topic: http://www.ti.com/lit/an/slva444/slva444.pdf

One last thing: make sure that you provide adequate recirculation diodes. If you are using FETs that are meant for this purpose, you may be able to rely on their body diodes (refer to the datasheet to make sure they're beefy enough) or you can optionally turn on the low side FET to let it conduct when the high side FET is off.

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