What is high side current limiting? While google searching for the term I have found ICs that describe their application as "high side load switching". Is this the same thing or something utterly different? Furthermore, the term implies that there is low-side current limiting also? What is this?
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It's about where current sensing is done - between voltage terminal and load for high side and between load and ground for low side.
High side current sensing is harder to achieve as it implies a big common mode voltage that must be dealt with in current sensing device. Low side is easy to do, but creates often undesirable effects like unstable ground.
Image is taken from eetimes article.
miceuz
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The "high side" in high side current limiting refers to the placement of the current limiting circuitry. If your current limiter is tied to the positive supply rail, it's called a high side current limiter.
This applies not only to current limiting. Anything that has to be placed in series with a load will be high- or low- side. A low-side switch will be placed between the load and the negative supply rail (GND). A high side current shunt will be placed between the positive supply rail and the load. And so on.
An N-MOSFET will be usually placed low-side. A P-MOSFET will be placed high-side. An NPN transistor will be placed low side, a PNP transistor high side.
Christoph B
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