So I was revisiting STA540 lately and found out, through manual measuring, that the metal tab of the chip is tied to the stand-by pin. Do I need to isolate the chip from the heatsink if the heatsink is tied to earth (not DC common)?
It is interesting that the datasheet never mentions what the metal tab is tied to.
It is interesting that the datasheet never mentions what the metal tab is tied to.
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Any metal device tab should be considered "hot" and be isolated from the (normally grounded) heat sink.
In this case, the tab is connected to device ground, but it may still need isolation for noise issues.
In this case, the tab is connected to device ground, but it may still need isolation for noise issues.
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I answered my own question by reading Sec. 6.5 of the datasheet -- it appears that the ST-BY pin is driven by a voltage source (though need to be current limited). I was searching for ST_BY instead of ST-BY and missed that section.