Comments on: An ADC and DAC Least Significant Bit (LSB) https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/ Electronics Design and Modeling with Emphasis on Analog Design Thu, 12 Jun 2025 20:08:59 +0000 hourly 1 By: Boss Manno https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-65763 Thu, 12 Jun 2025 20:08:59 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-65763 Very helpful article on LSB’s in a A/D converter. Thanks

]]> By: Fran javier Busto https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-49625 Fri, 15 Jul 2022 09:28:55 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-49625 All rigth! one efect of knowedge and the tell very well comprensive. Many thank´s for article.

]]> By: Steve https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-48119 Mon, 26 Jul 2021 03:51:28 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-48119 Thank you for the great help!
I’m wondering whether now ADI changes the FS definition or not. Since from Table8 in AD7685 datasheet (https://www.analog.com/media/en/technical-documentation/data-sheets/AD7685.pdf), the code ‘FFFF’ corresponds to ‘FSR – 1LSB’ It seems that FSR (or FS !?) is the Vref in this article. Your response is much appreciated!

]]> By: Floky https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-48117 Sun, 25 Jul 2021 16:51:27 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-48117 Gracias muy didáctico el artículo. Realmente fue de mucha ayuda.

]]> By: Emilio Blas https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-47439 Fri, 12 Feb 2021 04:14:44 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-47439 El FSR =2.55V y el error es 0.1% FSR ¿Cuál es el error total del ADC de 8 bits? ¿Cuál es el LSB? ¿Cuál es el V máximo? ¿la resolución?

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-47195 Mon, 25 Jan 2021 01:55:31 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-47195 In reply to Adam.

It is the same formula:
Vin = (Vref/2^N) x ADC – (Vref/2^N)

Here is for 0 volts input:
If Vin = 0, then the ADC code is 0, which is decimal 1 (2^0)
Then Vin = (Vref/2^N) x 2^0 – (Vref/2^N) = (Vref/2^N) x 1 – (Vref/2^N) = 0

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-47194 Mon, 25 Jan 2021 01:50:41 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-47194 In reply to Adam.

It is actually
Vin = (Vref/2^N) x ADC – (Vref/2^N)

Here is an example: If Vin is at Full Scale (FS), then
Vin = FS = (Vref/2^N) x 2^N – (Vref/2^N) = Vref – 1LSB (as in equation 8 in this article)

]]> By: Adam https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-47188 Sun, 24 Jan 2021 14:25:26 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-47188 Ok, I corrected the formula for 0V input voltage:
Vin = LSB x ADC + LSB x (ADC/ADC)

]]> By: Adam https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-47187 Sun, 24 Jan 2021 13:38:23 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-47187 The lower ADC reading, the bigger error (up to 50%) if you are using the following very common on the Internet equation:
Vin = (Vref/2^N-1) x ADC

]]> By: Adam https://masteringelectronicsdesign.com/an-adc-and-dac-least-significant-bit-lsb/#comment-47186 Sun, 24 Jan 2021 13:36:15 +0000 http://masteringelectronicsdesign.com/?p=1331#comment-47186 So, the only correct equation to calculate voltage from any ADC reading is:
Vin = (Vref/2^N) x ADC + (Vref/2^N)

]]>