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I have the following circuitry: Battery Supply => Current Monitoring Circuitry => DC Motors

Battery Supply: 4AA NiMH batteries - 4*1.2V (1.5mAh * 4)

Current Monitoring Circuitry: Max 4378 chip (contains 4 current-sense op amps)

I have used the Max 4378 chip for monitoring the energy levels of low-power applications. But now I want to use it to measure the energy consumption of driving two motors. Unfortunately, the chip has a max current supply, Icc, of 2.2mA.

Is there a chip I can use for energy monitoring that doesn't get fried by high currents in the order of 1.5 - 2 Amps? or perhaps an alternate method?

Thank you.

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You can use a current sense ampflifier that has an external sense resistor. TI offers several, for example. Then you can choose the sense resistor value as low as you like to suit the current levels you need to measure.

With high current, for accurate measurements you'll want to be sure that your sense resistor has a low TCR so that self-heating doesn't cause the circuit's overall gain to shift.

EDIT

Looking at the datasheet for the part you mentioned, you are already using the correct type of device. The normal application circuit for your part looks like this:

enter image description here

The Icc spec is a promise by Maxim that the current going in to the VCC pin of this chip will not exceed 2.2 mA. It has nothing to do with the current being sensed, which is indicated by the ILOAD arrow on the diagram.

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  • \$\begingroup\$ But the devices on the link have a maximum current limit of 2.8mA. Can they still withstand high currents of ~2Amps? I am reading through ACS758/ACS712 chips at the moment as mentioned here: bit.ly/1mNbrIq Please, let me know what you think. \$\endgroup\$ – JJT Apr 3 '14 at 17:43
  • \$\begingroup\$ You need to tell us what devices you are talking about. If a device only needs 2.8 mA, normally it will only draw 2.8 mA. If you force 1 A into it, you will probably destroy it. But what does that have to do with the current monitoring circuit? \$\endgroup\$ – The Photon Apr 3 '14 at 17:45
  • \$\begingroup\$ Thank you so much for correcting me - Yes, I got confused between Iload and Icc. \$\endgroup\$ – JJT Apr 3 '14 at 22:40

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