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Mosfets bootstrapping totem pole driver circuit

2017-08-15 02:39  
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A totem pole is a certain type of driver, used to amplify square waves (and sine waves, with additional components to prevent distortion!) into a stronger square wave for driving other types of semiconductors faster. A totem pole driver can be used to more effectively driveMOSFETS , (which will be explained in the next step, actually), and IGBT's. The increase in current allows the semiconductors to turn on and off faster, reducing heating.When driving MOSPOWER in a totem-pole output configuration, it is necessary to have the gate voltage 10 to 15 V positive with respect to the source in order to handle load currents near the MOSPOWER maximum ratings. The D169 lends itself to bootstrapping because of its high-voltage ratings. In the circuit shown, the voltage on the 2000-pF bootstrap capacitors is applied via diode OR gates to the V terminal.Therefore, regardless of which output is high, 30 Vis present at V . Maximum switching frequency is determined by the input capacitance of the MOSPOWER transistors used.Bootstrapping involves the use of positive feedback from output to input of an amplifier, of nearly unity gain, in such a way that a particular point in the circuit is "pulled up as if by its own bootstraps".The bootstrap technique is used to make a low value gate resistor Rg appear to have a much higher value as seen by the input signal.


  
Totem-pole-driver-with-bootstrapping