Is it possible to only use high side part of IR2103 mosfet driver ic, being fully functional, without adding low side driver external components?

IR2103 datasheet


1 Answer 1


Is it possible to only use high side part of IR2103 mosfet driver ic

enter image description here

You can: -

  • Use the bottom only
  • The top only
  • Both as half a H bridge
  • Not use both simultaneously (and independently) because of the shoot through protection prevents this (thanks to @StainlessSteelRat for pointing this out): -

enter image description here

The lower side MOSFET connection is a high impedance with a few nF of capacitance and leaving it open circuit won't cause problems.

  • \$\begingroup\$ Thx @Andy-aka: electronics.stackexchange.com/users/20218/andy-aka: Difficulty is, that voltage between Vb and Vs is just around Vcc level, but not bootstrapped, with 100nF Ct film capacitor and high speed Schottky diode UF5405 verified, without low side driver. How could I confirm that it is no undervoltage lockout of high side driver or too slow diode or too slow or low input current supply (now ~2.5kHz pwm on Hin)? \$\endgroup\$
    – beyondtime
    Mar 1, 2020 at 16:24
  • \$\begingroup\$ Bootstrapping, if required, needs a decent swing on Vs. If that doesn’t occur then you can still use the upper MOSFET without the bootstrap capacitor but you need to raise Vb above Vcc by the amount of gate drive voltage required. \$\endgroup\$
    – Andy aka
    Mar 1, 2020 at 16:40
  • \$\begingroup\$ So there's only bootstrap voltage rise on Vb if there is grounded (floating levels, e.g. isolated dc-dc converters?) load to high side mosfet (means i could not use a bootstrap circuit of ir2103 for providing high side voltage for several equally driven high side mosfets, if Ct capacity and Vcc input current would be sufficient)? \$\endgroup\$
    – beyondtime
    Mar 1, 2020 at 16:54
  • \$\begingroup\$ I’m trying to piece together what you are asking but without punctuation I’m getting confused. Use shorter sentences please and try and be a tad more coherent. For instance you are bracketing a question within a sentence right at the beginning and this is throwing me off. Why don’t you draw what you think you want? \$\endgroup\$
    – Andy aka
    Mar 1, 2020 at 17:18
  • 1
    \$\begingroup\$ No, you need a High side MOSFET and grounding load to be connected AND you need to be driving it up and down continuously for boot strapping to be effective. You can’t have slow on off signals because the bootstrap cap gets discharged. \$\endgroup\$
    – Andy aka
    Mar 1, 2020 at 17:44

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