I had read in TCA0732 datasheet that its current supply can't be greater than some decades of mA (+14mA for +15V voltage supply) but it can provide 1A of current how can that be possible, the same thing for OP2544 max supply current is 30mA and it can provide 2A of output current these amplifiers amplify voltage and also current where the power comes from ?? Datasheets:http://www.onsemi.com/pub_link/Collateral/TCA0372-D.PDF


  • 2
    \$\begingroup\$ When it's doing nothing, it takes 15mA to power itself. When it's supplying 1A, it consumes 1A plus that 15mA (plus probably a little extra). \$\endgroup\$
    – user16324
    May 6, 2016 at 10:11
  • \$\begingroup\$ @BrianDrummond I think you are right because it is wrote that RL is connected to ground that is mean no charge in the output \$\endgroup\$
    – berem
    May 6, 2016 at 10:29

1 Answer 1


The supply current is what the op amp(s) require in order to operate. If you measure all the current going from the positive supply pin to the negative supply pin you will get a current within that value. The output current, on the other hand, is between the supply pins and the output. This is not consumed by the device but rather is delivered to the load.

  • \$\begingroup\$ Where does this current come from? does that mean that the amplifier needs to be supplied by a generator which can deliver more than 1A of current ?if the whole circuit is supplied by a generator which delivers 0.5A max current, for example, is that still possible ? \$\endgroup\$
    – berem
    May 6, 2016 at 10:23
  • 1
    \$\begingroup\$ You still need a current source that can provide all the current your entire circuit needs. You can't get around that. \$\endgroup\$ May 6, 2016 at 10:27
  • \$\begingroup\$ Under typical audio amplifier circumstances, it can appear less. For instance if you have a 0.5A power supply, and are supplying 1A peak current to the output on an audio waveform which is only +ve for 50% of the time, then as long as you have a large resevoir capacitor on the supply input, you can deliver the 1A peaks, while drawing 500mA average. If it's a DC application, then your power supply must be able to supply continuously whatever you output (plus the 15mA or so that the amplifier internal workings consume!). \$\endgroup\$
    – Neil_UK
    May 6, 2016 at 10:35
  • \$\begingroup\$ If the current source is limited to 0.5A, the supply voltage will collapse and the signal will be clipped when demand exceeds this. As Neil says, reservoir capacitors can help, to deal with short term current peaks. \$\endgroup\$
    – user16324
    May 6, 2016 at 10:36

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