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Old 2nd September 2011, 07:47 AM   #1
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Default Hall-effect current sensor for output stage over-current protection

I am considering to use a hall-effect current sensor such as ACS-712 (http://www.allegromicro.com/en/Produ.../0712/0712.pdf) to protect amplifier output stage. The resistance of the copper conductive path of ACS712 is just 1.2 mR which is effective zero resistance in the intended application. It is also electrically isolated from other part of the chip. The output analog signal can be used to drive a relay circuit or sampled by ADC of an MCU.

Since the conductive path is just a piece of copper, it should not introduce any distortion. Although the chip employes chopper stabilization technique, the electrically isolated path should not be picking up any interference. Well, it might via capacitive or inductive paths.

Any comment?
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Old 2nd September 2011, 05:21 PM   #2
cbdb is offline cbdb  Canada
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Looks like a great idea.

Well, it might via capacitive or inductive paths.
But probably no worse than any other technique.
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Old 2nd September 2011, 05:57 PM   #3
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More than ten years ago I did similar current sense-protection, adjustable to any current-trigger level as needed. It works perfectly till these days.
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Old 2nd September 2011, 08:03 PM   #4
Spiny is offline Spiny  United Kingdom
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I posted one a while back, Still in daily use
hall effect dc speaker protection
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Old 6th September 2011, 03:07 PM   #5
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Lazy Cat and Spiny,

Yes, I visited your thread.

I plan do all the things in an MCU which samples Vce, temperature, etc. Transistor SOA parameters can be input to the firmware. Temperature data can be used for derating.
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