Mesure AC(300 volt) with MCU

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baby_1

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Hello
i want to measure a AC voltage 300 volt and 50Hz with MCU ADC , as you know i can use transformer to isolate and decrease the input voltage(300 volt) and then rectifies it then measure by MCU , or can rectifies the input voltage and then decrease voltage with resistor divider network.
but i have these problem:
1-if i want to use transformer it use big size in my board but isolated it good for me
2-it i use the diode and resistor it has a small size but doesn't have any isolator

is there any way that isolate the input voltage and has a small size? IC available ?
 

Your best bet is a low power 240/6.3 v transformer. Size is relative but a transformer with <2 VA rating should in the order 2.5 cm.
 
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Thanks RcinFLA
doesn't have a simple and small size to this purpose?
 

Thanks Jestin
as you know above circuit that you mention is used for pulse detector and with optocoupler with non-linear CTR we can't sense the accurate voltage.do you know a optocoupler with high accuration ?
 

Hi Baby-1
Who told that transformer is large ? consider that you have a 50 ma transformer , it is pretty small . ( i saw many of them until now )
and about resistors , then you can add a linear opto coupler such as IL300 .
Best Wishes
Goldsmith
 
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