Understanding Modern Power MOSFETs - Fairchild Semiconductor
Understanding Modern Power MOSFETs - Fairchild Semiconductor
Understanding Modern Power MOSFETs - Fairchild Semiconductor
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
7<br />
High Side Switch Options<br />
• Simple drive circuit<br />
• Higher RDS(ON) than for N-channel<br />
• Watch out for VGS max when driving<br />
8<br />
V g<br />
V dc<br />
High side<br />
switch<br />
(P-channel)<br />
Load<br />
resistor<br />
V g<br />
V dc<br />
High side<br />
switch<br />
(N-channel)<br />
Load<br />
resistor<br />
• Turns on fully only if V g > V d + 10V<br />
• Bootstrap or charge pump drive<br />
needed<br />
Uni-directional and Bi-directional<br />
Switches<br />
• All <strong>MOSFETs</strong> have a body diode<br />
• A single MOSFET switch can block<br />
voltage in only one direction<br />
• To block voltages in both directions,<br />
a diode is needed<br />
• This allows uni-directional current<br />
flow<br />
• To block voltages in both directions,<br />
allowing bi-directional current flow, a<br />
second MOSFET is needed<br />
• This configuration is used in<br />
• Battery chargers<br />
• Lighting dimmers<br />
4
Change language