Design issue Serial Comm. Isolator with Level shifting

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geobabu

Joined Aug 13, 2008
6
Hi,
I am trying to implement a isolation in between a serial communication system. One side its have a RS232-TTL(MAX232 circuit) level terminal & other side contains a 3.3V based microcontroller whose power is directly driven from a transformer less capacitor based power supply. I tried a setup a circuit that mentioned in the attached file ,but it doesn't helped helped me. Please help me to rectify the error in this circuit.
Thanks&Regards,
Geo
 

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leftyretro

Joined Nov 25, 2008
394
Hi,
I am trying to implement a isolation in between a serial communication system. One side its have a RS232-TTL(MAX232 circuit) level terminal & other side contains a 3.3V based microcontroller whose power is directly driven from a transformer less capacitor based power supply. I tried a setup a circuit that mentioned in the attached file ,but it doesn't helped helped me. Please help me to rectify the error in this circuit.
Thanks&Regards,
Geo
Well if built like drawn then your missing +5vdc power for the Max232 chip, it goes to pin 16.

http://www.datasheetcatalog.org/datasheet/texasinstruments/max232.pdf

Lefty
 
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