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USING THE SAG PIN AS POWER SUPPLY MONITOR

Question asked by TrendChaser89 on Feb 10, 2013
Latest reply on Apr 26, 2013 by hmani

Hi All,

 

                I'd like to ask about how the SAG pin of ADE7753 could be used as a power supply monitor.  On the datasheet, I've read that it would go logic low whenever ADE7753 goes into an inactive state and the analog supply (AVDD) is less than 4V +/-5%. I wanted to save the energy reading on an EEPROM when a brownout occurs.  Temporarily, I programmed the MCU to save data on a regular basis since I still have to figure out how I could make use of the SAG pin as an external interrupt to the MCU.  I placed a zero on the DISSAG bit of ADE7753's MODE register and I monitored the state of the SAG pin using an oscilloscope.  I found out that it stays low all the time even if the analog supply is 5 V and the ADE7753 is operating normally.  What else should I do to make the SAG pin work?

 

                Also, I observed that the ADE7753 chip heats up a lot whenever I remove the analog inputs to channel 2 (220 V line) while the 5 V power supply is still active.  Is this normal?  Will it eventually burn the chip?  I am a bit worried because I’m planning to place a large capacitor across the 5 V supply to hold it for a second or two during a brownout.  This is to ensure that my MCU has enough time to save its last energy reading before it runs out of power supply. 

 

                Thanks a lot for all the help.

 

Best Regards,

 

TrendChaser89

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