AN-9044 - Fairchild Semiconductor
AN-9044 - Fairchild Semiconductor
AN-9044 - Fairchild Semiconductor
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Mini DIP (SPM3) Application Note (2012-07-09)<br />
Figure 8.2 VF-IF curve of two bootstrap diode<br />
8.5 Charging and Discharging of the Bootstrap Capacitor during PWM-Inverter<br />
Operation<br />
The bootstrap capacitor (CBS) charges through the built in bootstrap diode from the VCC supply when<br />
the high-side IGBT is off, and the VS voltage is pulled down to ground. It discharges when the high-side IGBT<br />
is on.<br />
Example 1: Selection of the Initial Charging Time<br />
An example of the calculation of the minimum value of the initial charging time is given with reference<br />
to equation (8.1).<br />
Conditions:<br />
CBS = 22F<br />
Duty Ratio of PWM()= 0.5<br />
DBS = built in bootstrap diode including around 15 resistance characteristics<br />
VCC = 15V<br />
Vf (Forward voltage drop across the bootstrap diode)= 0.5V<br />
VBS (min) (The minimum voltage of the bootstrap capacitor)= 13V<br />
VLS (Voltage drop across the low-side IGBT or load)= 0.7V<br />
© 2008 FAIRCHILD SEMICONDUCTOR - Smart Power Module<br />
40
Change language