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Discussion in 'Electronic Basics' started by kell, Nov 14, 2005.

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  1. kell

    kell Guest
    I tried to use the IR2153 to run a half bridge using two n-channel
    mosfets as in the circuit diagram on the first page of the data sheet,
    and it didn't work.
    I discovered that HO only sinks, it does not source.
    LO works; it sources and sinks, and the cap for Vb does take a charge.
    I found this out by slowing the timing down to about one hertz and
    using grain-of-wheat lamps to see what the outuputs were doing.
    Same thing happened with both chips that I tried.
    Has anyone used the IR2153, and what do you have to do to get the high
    side drive to work?
  2. Guest

    Its not going to work at 1 Hz. You need a high speed diode in the
    circiut a !N4001 wont do.
  3. wrote...
    It works fine at 1Hz, or at DC, if a separate floating power supply
    is created for the HI-side driver section. A few years ago I posted
    the schematic of a high-speed 250V 50-ohm pulse generator using this
    approach with an IR2113, a chip with similar MOSFET drivers.
  4. John - kd5yi

    John - kd5yi Guest

    According to the diagrams on page 6, both outputs are source/sink.
    Something else is wrong.

    Good luck.

  5. Jon

    Jon Guest

    A couple of things to check:
    Are you matching the recommended values of Rt, Ct to your switching
    frequency? Also the Voltage on the cap for Vb must be higher than Vs,
    by an amount equal to or greater than gate threshold voltage of the FET
    you are using.
  6. kell

    kell Guest

    Thanks for the replies. I'll go into a little more detail.
    At first I tried to run it with a .01 uF cap and a 10 k resistor for
    the timing, to
    drive a ferrite transformer, using rectified mains for power. I used a
    MUR160 for the bootstrap diode. I had a 10 uF cap for the Vb/Vs cap.
    I used IRF740 mosfets. I don't have a scope so when the circuit
    wouldn't work I decided to check it out by bringing the timing down to
    something I could check by eye with test lamps. I disconnected from
    the high voltage and used a 12 volt battery for the test. I
    connected little lamps from pin 6 to Vcc and ground and set the timing
    to about 1 hz with an electrolytic cap and a 10 k resistor. The lower
    mosfet worked, but not the upper. So I tested pin 7, which drives the
    upper mosfet. It was sinking but not sourcing.
    It is my understanding that the chip is supposed to provide its own
    power for the high side because the Vb cap charges up every time the
    lower mosfet turns on, and this provides power for the upper driver.
    My test illustrated that this was happening. During the test I used a
    680 uF cap. The cap took on a 12 volt charge.
    I don't see why I should need a separate floating supply to make this
    thing work. The cap is right there providing a floating power supply
    for driving the upper mosfet. Something else is going on here.
    I'm going to take another gander at the datasheet now.
  7. Pooh Bear

    Pooh Bear Guest

    IR have an app note about providing a seperate hi side supply specifically
    for low frequency operation. Uses a 555 IIRC.

  8. kell

    kell Guest

    This note from IR addresses the subject. I still haven't figured out
    the problem.
  9. kell

    kell Guest

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