N-Channel Vs. P-Channel (driving a 24V load from CMOS)
N-Channel Vs. P-Channel (driving a 24V load from CMOS)
(OP)
Hi all,
I recently build a circuit using Logic Level P-Channel Mostefs to drive a 24V load from a microcontroller 0-5V level.
Gate to microcontroller, Drain to Load and source to 24V.
That dind't work. Works only at 5V. From 5V up the transistor is allways on. I think I need to use some kind of mosfet driver. (I was thinking that using a Logic level transistor was enough). My mistake.
Aparently such a simple circuit is possible using a N-Channel Mosfet. Gate to microcontroller, drain to Load and source to ground. Since we are "giving ground" to the load everthing works.
Can you guys confirm this?. I think I still have a lot to learn concerning circuit design.. :(
I dont want to make more mistakes.
Thanks in advance
M.
I recently build a circuit using Logic Level P-Channel Mostefs to drive a 24V load from a microcontroller 0-5V level.
Gate to microcontroller, Drain to Load and source to 24V.
That dind't work. Works only at 5V. From 5V up the transistor is allways on. I think I need to use some kind of mosfet driver. (I was thinking that using a Logic level transistor was enough). My mistake.
Aparently such a simple circuit is possible using a N-Channel Mosfet. Gate to microcontroller, drain to Load and source to ground. Since we are "giving ground" to the load everthing works.
Can you guys confirm this?. I think I still have a lot to learn concerning circuit design.. :(
I dont want to make more mistakes.
Thanks in advance
M.





RE: N-Channel Vs. P-Channel (driving a 24V load from CMOS)
TTFN
RE: N-Channel Vs. P-Channel (driving a 24V load from CMOS)
I prefer to use a bit of extra money and buy an integrated switch for this kind of stuff, they are available from a lot of suppliers.
Do an search on "High side switch", and example can be seen here: http:/
Regards,
Benta.
RE: N-Channel Vs. P-Channel (driving a 24V load from CMOS)
If your load can only be switched on and off from the 24V side, then you can use your P-channel MOSFET in combination with one of the schemes that IRstuff mentioned. I typically implement the latter by adding an N-channel MOSFET with a resistor.
And in regards to your not wanting to make any more mistakes, good luck with that. I generally make several mistakes before I even start work each day.
RE: N-Channel Vs. P-Channel (driving a 24V load from CMOS)
For those MOSFETs, the maximum gate-source voltage is generally 20 V. Use a resistor divider to keep it under the max.
RE: N-Channel Vs. P-Channel (driving a 24V load from CMOS)