| ??? 12/14/05 23:19 Read: times |
#105251 - Not quite Responding to: ???'s previous message |
Erik Malund said:
Unless something has happened it seems/seemed that the smaller the Ron is the more drive the mosfets need. Thus you may end up with a separate power supply just for the gate voltage. That is simply not true. Any MOSFET has 'essentially zero' gate current when it is in a steady state. What you are confused with is the dynamic drive requirements, which is a different thing. Low RDS(on) MOSFETs have high gate capacitance; up to several nF. Charging and discharging this capacitance in nanoseconds several hundred thousand times a second does indeed require a substantial drive current. However, when switching once every few seconds or so and with no need for nanosecond rise- and fall times, even a relatively weak drive will suffice. Rob. |
| Topic | Author | Date |
| Connecting to power | 01/01/70 00:00 | |
| many possibilities if you switch before | 01/01/70 00:00 | |
| do you mean 7805? | 01/01/70 00:00 | |
| many | 01/01/70 00:00 | |
| before or after regulator | 01/01/70 00:00 | |
| High performance power FET? | 01/01/70 00:00 | |
| maybe, maybe not | 01/01/70 00:00 | |
| Not quite | 01/01/70 00:00 | |
| Misunderstanding? | 01/01/70 00:00 | |
| Not true either | 01/01/70 00:00 | |
| Examples? | 01/01/70 00:00 | |
| IRF has a pageful of them | 01/01/70 00:00 | |
| Ok, maybre I was not clear, but correct | 01/01/70 00:00 | |
| Ehm, no | 01/01/70 00:00 | |
| which I also covered | 01/01/70 00:00 | |
| Well | 01/01/70 00:00 | |
| (not so) recent knowledge | 01/01/70 00:00 | |
| Even the voltage! | 01/01/70 00:00 | |
| LM317 | 01/01/70 00:00 | |
| NMOS? | 01/01/70 00:00 | |
| IRF got those too | 01/01/70 00:00 | |
| Of course... | 01/01/70 00:00 | |
Load switching? | 01/01/70 00:00 |