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I'm working on digesting the data sheet for the Texas Instruments bq34z100-g1 fuel gauge IC. I'm looking to use this chip with a 2 cell lithium polymer battery pack. If using a multi cell pack the data sheet recommends using the following voltage regulator setup. I'm assuming it's low power but i'm not sure how. I've never seen this setup before. What makes it special.

schematic

simulate this circuit – Schematic created using CircuitLab

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    \$\begingroup\$ Its nothing special, on the contrary, its one of the simplest one can do, and the datasheet explains that the chip has its own regulator built in and that this is just a prereg \$\endgroup\$ – PlasmaHH Oct 30 '15 at 22:47
  • \$\begingroup\$ What makes you think it is special? \$\endgroup\$ – JonRB Oct 30 '15 at 23:08
  • \$\begingroup\$ It's special if you want it to be special. \$\endgroup\$ – Andy aka Oct 30 '15 at 23:26
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It's just a bog-standard series-pass linear reg with with a FET instead of a BJT.

As @PlasmaHH notes, it is often used a pre-regulator in more sophisticate setups. It allows you drop some voltage (and thus power/heat) on an external element. Doing this also lets you extend the voltage input range of your more expensive IC regulator. TI has a separate appnote in which they suggest this.

enter image description here

This prereg idea (even with BJTs) not at all an uncommon. Cordless phones do this a lot for instance because they also use the [higher] pre-regulated voltage directly for a few components and they also derive a lower stable voltage for most of the digital parts. So in those setups it serves a double function (more bang for the buck).

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