i need some expert to help me .will my circuit gonna work

 

Hi Pin,
Welcome to AAC.
Please post your best attempt at solving the problem, we can then help you.
E

 

View attachment 346758

i need some expert to help me .will my circuit gonna work

Hi,

As long as you have the right voltage divider ratio and the program code to match, it will work.
For example, if your voltage divider has a ratio of 4 to 1 exactly, then when you apply 4 volts you get 1v to the ADS1115 chip. The program code in the microcontroller used with the ADS chip would then have to multiply that by 4 to get the actual voltage applied to the voltage divider.

You do have to observe the proper resistance part of the impedance for the voltage divider because you want to meet the internal leakage spec of the ADS chip. That's the resistive part only as you can place a 100000uf cap across R4 and still not meet that spec. That would be the equivalent resistance for a DC signal not AC and that's with no transient either.
Yours is probably 10k in parallel with 33k but you also have to know the equivalent resistance of the source feeding the 10k. If the resistance of the source was 5k then the equivalent resistance the chip sees is 15k in parallel with 33k.

What you have to do then is compute your actual divider ratio and adjust your code, and also check the leakage spec of the ADS chip and see if your equivalent divider resistances are good enough over the temperature you intend to see this used at.

 

Hi,

As long as you have the right voltage divider ratio and the program code to match, it will work.
For example, if your voltage divider has a ratio of 4 to 1 exactly, then when you apply 4 volts you get 1v to the ADS1115 chip. The program code in the microcontroller used with the ADS chip would then have to multiply that by 4 to get the actual voltage applied to the voltage divider.

You do have to observe the proper resistance part of the impedance for the voltage divider because you want to meet the internal leakage spec of the ADS chip. That's the resistive part only as you can place a 100000uf cap across R4 and still not meet that spec. That would be the equivalent resistance for a DC signal not AC and that's with no transient either.
Yours is probably 10k in parallel with 33k but you also have to know the equivalent resistance of the source feeding the 10k. If the resistance of the source was 5k then the equivalent resistance the chip sees is 15k in parallel with 33k.

What you have to do then is compute your actual divider ratio and adjust your code, and also check the leakage spec of the ADS chip and see if your equivalent divider resistances are good enough over the temperature you intend to see this used at.

Thanks sir , i'm understand now

 

You also need to consider what happens if you leave pins 5,6 and 7 unconnected.

 

You also need to consider what happens if you leave pins 5,6 and 7 unconnected.

Thanks for the reminder! Since those pins are only used to read voltage, I think leaving them unconnected shouldn't cause any major issue — but I’ll definitely keep it in mind just to be safe. Appreciate your input!"

 

Thanks for the reminder! Since those pins are only used to read voltage, I think leaving them unconnected shouldn't cause any major issue — but I’ll definitely keep it in mind just to be safe. Appreciate your input!"

I use the 'unused ADC pins for a sanity calibration check if I have at least two, one or more goes to VSS/GND and the other goes to VDD or a external Vref if one is used. This way I can check ADC operation with known external values quickly.