I'm new to here. I am recently making an H-bridge inverter with IR21531D (here is the data sheet). I connected them this way:

enter image description here When I measure the Lo and Ho pin with passive probe and differential probe (I only have one differential probe), and I got this enter image description here I use the differential probe to measure the voltage between Ho and VS, and the Lo and Ho gate signal are overlapped. The dead time is too large which is not even close to the datasheet (0.6 us typ.). If I connect my FET, the circuit will short together.

Can any master here could help me out? Thank you.

  • \$\begingroup\$ Is the switching frequency matching that of your calculations? \$\endgroup\$ – winny Mar 7 at 10:36
  • \$\begingroup\$ The frequency is determined by the timing resistor and timing capacitor, according to the data sheet, i am having the correct frequency. \$\endgroup\$ – dumbstudent Mar 8 at 6:27
  • \$\begingroup\$ Any difference if you load the outputs slightly? Say 47 kohm Lo to ground and Ho to Vs? \$\endgroup\$ – winny Mar 8 at 6:53
  • \$\begingroup\$ The FET gate is able to take up the voltage from Ho and Lo. Anyway, I rebuilt the circuit and things are fine now. Thank you very much for your attention! \$\endgroup\$ – dumbstudent Mar 11 at 5:40

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