Author Topic: Art of Electronics Bad Idea question  (Read 934 times)

0 Members and 1 Guest are viewing this topic.

Offline avectorTopic starter

  • Newbie
  • Posts: 5
  • Country: us
Art of Electronics Bad Idea question
« on: October 19, 2019, 07:22:43 pm »
I recently bought Art of Electronics 3rd Edition, which does not have the "Bad Circuits" from the 2nd Edition. In pursing the material and the website, I came across this "Bad Circuit" for a high side power switch using PMOS:

https://artofelectronics.net/bckt-high-side_power_switch/

I see that the PMOS is going to take a long time to turn off with only ~480uA to increase gate voltage, but I don't see anything fatally wrong with the circuit. Yet everywhere else on the internet I looked used a BJT NPN instead of an NMOS to drive the gate. I was wondering if someone could look up this circuit in the 2nd Edition or if anyone knew more (or saw something obvious I missed)?
 

Online edavid

  • Super Contributor
  • ***
  • Posts: 3384
  • Country: us
Re: Art of Electronics Bad Idea question
« Reply #1 on: October 19, 2019, 07:38:48 pm »
The maximum VGS of the P MOSFET is likely to be exceeded.
 
The following users thanked this post: Yansi

Online Zero999

  • Super Contributor
  • ***
  • Posts: 19531
  • Country: gb
  • 0999
Re: Art of Electronics Bad Idea question
« Reply #2 on: October 19, 2019, 08:58:34 pm »
Fortunately it's easy to fix by adding another resistor.


Another alternative is a BJT with an emitter resistor.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf