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In a Half bridge MOSFET switching circuit, in order to prevent a "short" circuit through the high and low sides, I need to delay the turn on of the high/Low side until the Low/High side has turned off. I still need the switching speed to be as high as possible. this is necessary because this is a very high speed switching circuit.

( a half bridge has current flowing from the positive supply through the High side through load to ground, and alternately from ground through the load and Low side to negative supply.)

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  • \$\begingroup\$ What is your current schematic? the approach will be entirely dependent on that. \$\endgroup\$ – Tom Carpenter Jan 19 '17 at 16:42
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    \$\begingroup\$ You can buy MOSFET half-bridge drivers with built-in dead time and high current (fast) gate drive. You can use an MCU with built-in programmable dead time. You can design the delay yourself using various techniques.. lots of options. \$\endgroup\$ – Spehro Pefhany Jan 19 '17 at 16:44
  • \$\begingroup\$ This is for a college project- as of now I am being required to built the driver- I don't need a complete answer, ideas (or suggested reading or websites) would also help. can you give examples of some options? \$\endgroup\$ – Mordechai Salomon Jan 19 '17 at 17:13
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Start with this: -

enter image description here

And then invert the output of the OR gate.

Both gates should be schmitt trigger types. The RC time constant and the schmitt trigger high and low thresholds produce the deadband timing.

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Thank you for the answers. We ended up using a gate driver with separate high and low inputs, and the pwm is being digitally switched. I am implementing the delay digitally, which avoids the initial problem.

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