LM324 shut down

Go To Last Post
6 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi there,

Using the LM324 (2*LM358 in the same package), in a new product design I would like to drop the current consumption whenever I choose because the power supply is a battery. So having 2,5 - 3,5 V to the 4 inputs I would like to shut down the power supply of the ic, in order to stop the power consumption.

Is there any problem of doing this using this method. I mean that is tere any possibility for burning the ic because of the non-supply when there is voltage in 1 to 4 inputs.

Thanks for your time,

Michael

Michael.

User of:
IAR Embedded Workbench C/C++ Compiler
Altium Designer

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

No that is no problem... the IC's output will just go to zero volt when the IC is off...

uC's: Atmega16, 32, 64, 128 and Attiny13
Lang.: C
Interests: Small scale robots AND sensor monitoring system

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There are also many modern low power quad opamps available with much lower power consumption than the 324 that may save you some more battery power.

Tom Pappano
Tulsa, Oklahoma

Tom Pappano
Tulsa, Oklahoma

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Agree with Tom.

However, you do need to be careful about devices being partially powered through non-power supply pins. There can than be an output voltage even though there is no supply. This is less of an issue with CMOS inputs than bipolar.

You could better use a device with an ENABLE input that internally turns everything off.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Since nearly all CMOS divices have diodes for protection, powering through an input is a problem with CMOS chips as well. To prevent this a resistor (e.g. 10 K) at critical inputs could help.

Since most bipolar chips don't have those diodes, I would say bipolar chips can even have an advantage here. The LM324 for example has PNP inputs, so without positve supply there should be no current until the maximum UBE voltage is reached.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Good point.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!