If your ADC input signal is below +2.5V. you can go for the Vref+ to +2.5V. Because to increase the resolution.
i think you are aware of 10Bit adc value. Mostly Internal ADC is about 10 bits. so 2^10 => 1024 steps. ADC counts from 0 to 1023.
If your input signal is 0V. ADC value is 0. If your input signal is maximum say about 2.5V, ADC count will be 1023.
Smallest change in input signal it can detect is about, 2.5V/1024 => 0.00244140625V. Each step increase at every 2.4mV.
If your reference voltage is about 5V, then +5V/1024 => 0.0048828125V .Each step increase at every 4.8mV.
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If your ADC input signal is below +2.5V. you can go for the Vref+ to +2.5V. Because to increase the resolution.
i think you are aware of 10Bit adc value. Mostly Internal ADC is about 10 bits. so 2^10 => 1024 steps. ADC counts from 0 to 1023.
If your input signal is 0V. ADC value is 0. If your input signal is maximum say about 2.5V, ADC count will be 1023.
Smallest change in input signal it can detect is about, 2.5V/1024 => 0.00244140625V. Each step increase at every 2.4mV.
If your reference voltage is about 5V, then +5V/1024 => 0.0048828125V .Each step increase at every 4.8mV.