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Using Smart High-Side Power Switches as a battery switch + current sensor + protection

Posted by Nick Arsov on August 11, 2012 at 6:58am

3689472936?profile=originalHi guys,

The Smart MOSFETs are now really smart enough to use them in such applications as RC High Current switches. More, they have a current sensing output, which could be used for current sensing instead of commonly used Schunt+IC .

An example for such a device is BTS50015 - BTS50015-1TAA-Data-Sheet-11-Infineon.pdf

The very low Rds of less than 1.5mOhm and 3.3-5V drive voltage capabilities make it a nice device for further researches. The ICs could be also connected in parallel for higher currents.

Here is a typical current sensing diagram from IS pin:

3689473105?profile=originaland a typical application:

3689473157?profile=originalI'm going to design some prototypes based on BTS50015 and BTS555 and after testing them I'll post the results.

Enjoy and have fun!

Nick

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Comments

  • Nick Arsov August 12, 2012 at 8:07am

    Hi Richard,

    Just an additional small explanation - BTS50015/BTS555 do not use a built-in shunt resistor which dissipates heat, but a sense FET which is in the main FET structure. The sense cells pass only a small fraction of the total load current in proportion to the ratio of their areas. This ratio is typically from 500:1 to 10000:1

  • Nick Arsov August 12, 2012 at 7:03am

    Yes, true...really fine devices with a huge potential. More, it has a excellent protection functions. Take a look at the datasheets for overcurrent and reverse polarity protection. I'm sure there are also alternative devices from International Rectifier for example and some other manufacturers.

  • John Rambo August 12, 2012 at 6:17am

    for $7 that's a fine device.

    I've been looking for this kind of function for two weeks and ended up with ACS712 for the current sensing together with MTP3055VL MOSFETS for a 5V controlled switching. Full circuit came to cost just above $6 with a weight close to that of a small relay, which I don't like.

  • Nick Arsov August 12, 2012 at 2:49am

    Hi John,

    Correction....you can find it for less than EUR 5.60. More you'll not obtain a current sensing function from a latching relay. More, using a high current relay, you'll have at least 50g load in the plane.

    Finally, as I said, this device is a basis for future developments as such devices have a huge potential.

  • John Rambo August 12, 2012 at 1:06am

    $20 for BTS555 price at farnell? A good latching relay costs $10, or, alternatively - one could get a a handful of premium logic level MOSFETS.

    How is this-one better?

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