ADS 1115 PGA
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- Dirae
- Posts: 19
- Joined: Thu May 11, 2017 7:14 am
ADS 1115 PGA
How can someone use the Programmable Gain Amplifier setting to determine the value of a bit of ADS 1115.
- adafruit_support_bill
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- Joined: Sat Feb 07, 2009 10:11 am
Re: ADS 1115 PGA
Table 3 of the data sheet shows the full-scale range for each gain setting: https://cdn-shop.adafruit.com/datasheets/ads1115.pdf
A one lsb change in the reading would correspond to the full scale voltage divided by 2^15. (32768)
A one lsb change in the reading would correspond to the full scale voltage divided by 2^15. (32768)
- Dirae
- Posts: 19
- Joined: Thu May 11, 2017 7:14 am
Re: ADS 1115 PGA
If the PGA setting = 1 or 2 or 4 or 8 or 16, and supply voltage VDD is larger than 4V, what is the maximum voltage the analog input can measure?
- adafruit_support_bill
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Re: ADS 1115 PGA
For those gain values, it can measure up to the full scale value from table 3 - or up to VDD + 0.3v whichever is smaller. As the warning states, v.Voltages more than VDD + 0.3v will damage the chip.
- Dirae
- Posts: 19
- Joined: Thu May 11, 2017 7:14 am
Re: ADS 1115 PGA
Thanks for your reply.
If i got you right, it means if PGA setting = 2, FS = ±2.048V and VDD = 5V, it means analog input can not measure beyond 2.048V. Am i right?
If i got you right, it means if PGA setting = 2, FS = ±2.048V and VDD = 5V, it means analog input can not measure beyond 2.048V. Am i right?
- adafruit_support_bill
- Posts: 88145
- Joined: Sat Feb 07, 2009 10:11 am
Re: ADS 1115 PGA
That is correct.
Please be positive and constructive with your questions and comments.