Author Topic: Is op amp supply current on datasheet per channel?  (Read 881 times)

0 Members and 1 Guest are viewing this topic.

Offline BootalitoTopic starter

  • Supporter
  • ****
  • Posts: 116
  • Country: us
    • EasyEda.com/TerryJMyers
Is op amp supply current on datasheet per channel?
« on: December 30, 2018, 03:54:08 am »
I'm searching for an optimized 4 channel op amp to drive a 4 parallel mosfets for an electronic load.  I'm able to achieve ~0.02A/uSwith an AD8630 by using a 330R resistor to gate or about 15mA per channel.  The AD8630 has an output short circuit current of 50mA, so I'm a bit overspec, but its stable.  I need more power!

The AD8534 says it has a "250mA Output".  Then I realized I didn't actually understand if the datasheet specification for "Output Current Limit", "Output Short Circuit Limit", etc, was for the entire device or per channel.  I figured these specs were for the entire device regardless of if its a single or quad channel amp.  But I really don't know!

I'm using the same mosfets as the Rigol Electronic load, and it has a claimed spec of 5A/uS with 12 Fets.  I think it has a 3.3R resistor and when you do the math with the gate charge its in the ball park of 5A/us.  How does one deliver 4Amps to a mosfet gate in the linear region in a controlled manner?  I mean you can use a gate driver, but that's just for slamming the gate open and shut. 
« Last Edit: December 30, 2018, 03:59:16 am by Bootalito »
 

Offline Nerull

  • Frequent Contributor
  • **
  • Posts: 694
 

Offline BootalitoTopic starter

  • Supporter
  • ****
  • Posts: 116
  • Country: us
    • EasyEda.com/TerryJMyers
Re: Is op amp supply current on datasheet per channel?
« Reply #2 on: December 30, 2018, 04:45:16 am »
Thanks

In an electronic load application the application of power is so brief as to be non-consequential though.  Although in that section it says the minimum resistor one should place on the output is 20R.  5V / 20R = 250mA.  But what if I'm using a quad package?  Does this mean I can put 20R resistors on each output?  Meaning that the entire package will be driving 1A of power for about 50us
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf