Question

The full scale output of 5mA. If the resolution is to less than 30$\mu A$, the required bits are ________

• A. 8

Answer 1

The correct option is A 8
Resolution = $\frac{I_{FS}}{2^n-1}$

Resolution $\le 30\times {10}^{-6}$

$\frac{5\times {10}^{-3}}{2^n-1}\le 30\times {10}^{-6}$

$1+\frac{5\times {10}^{-3}}{30\times {10}^{-6}}\le 2^n$

$167.66\le 2^n$

$2^n\ge 167.66$

$n\ge {\log }_{2}167.66$

$n\ge 7.38$

$n=8$