ISO1212: ref design for 240VAC input power detector

Terry Hu

Part Number: ISO1212
Other Parts Discussed in Thread: AMC1302, ISOM8115

Tool/software:

Hi Team,

My customer would like to design a 240VAC input power detector. Max power is 1.8KW.

Could you please advise whether ISO1212 is recommended for AC voltage sensing, AMC1302 is recommended for AC current sensing?

Do we have similar ref design? Thanks!

Best regards,

Terry

3 months ago

0 Andrew J 3 months ago

TI__Mastermind 26295 points

Hello Terry,

ISO1212 can be used with a shunt resistor in order to work with voltages higher than 60V. This method is detailed in 9.2.1.2.4 Designing for Input Voltages Greater Than 60 V. Please keep in mind that ISO1212 is a digital input isolator and will turn on when the input is over the threshold set by Rthr and Rshunt.

A different method will need to be used if the application needs analog AC voltage sensing. Isolated amplifiers - like AMC1302 - are used to accurately measure the AC voltage. As seen in ±480V Isolated Voltage-Sensing Circuit with Differential Output (Rev. A) or Voltage-sensing solutions | TI.com. ISOM8115 could also be used to sense the AC voltage if analog accuracy is not a concern.

Best,
Andrew

0 Terry Hu 3 months ago in reply to Andrew J

TI__Expert 3140 points

Hi Andrew,

Thanks for your reply! ISO1212 is not for voltage measurement. It's more likely an isolated switch for a pre-set threshold, right?

The product customer want to make is a smart plug with energy monitoring (watt meter). One way is measuring AC voltage and current, then calculate the watt. Customer didn't indicate the accuracy requirement. A rough measurement should be fine.

Can we use ISOM8115 for watt meter purpose?

Best,

Terry

+1 Andrew J 3 months ago in reply to Terry Hu

TI__Mastermind 26295 points

Hi Terry,

Yes, ISO1212 is more suited for an isolated switch with a pre-set threshold. Here is a different technote on these applications How to Design Isolated Comparators for ±48V, 110V and 240V DC and AC Detection (Rev. A).

ISOM8115 would be a good selection if the customer only needs a really rough analog measurement. The CTR can vary 100% to 155%.

If you would like to discuss the isolated amplifier products, I would recommend creating a new thread using AMC1302 to discuss which amp has the accuracy requirements needed for you.

Best,
Andrew

0 Terry Hu 3 months ago in reply to Andrew J

TI__Expert 3140 points

Thank you, Andrew.

Actually, I opened another thread using AMC1302 for discussion.

Best regards,

Terry

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ISO1212: ref design for 240VAC input power detector