Re:System separation in the Continental Europe Synchronous A...
by userbinator on Tuesday January 26, 2021 @09:33AM
(#25916132)
It's cheaper to build in a 32.768kHz crystal for timekeeping than try to access the grid frequency from the isolated low-voltage circuit.
Those products don't use isolated power supplies --- normally they use a capacitive dropper. A high-value resistor to an IC pin is sufficient to drive the clock counter, and a resistor is definitely cheaper than a crystal.
Those products don't use isolated power supplies --- normally they use a capacitive dropper. A high-value resistor to an IC pin is sufficient to drive the clock counter, and a resistor is definitely cheaper than a crystal.