Question

Question 4 5 pts (COS 3 & 4) An 8-bit DAC outputs a value of 5.10 V when the input is OxFF. What is the output when the input is 0x72? O 4.49 V 2.28 V 1.14 V 3.82 V

I want to confirm this answer as soon as possible thanks.

Answer 1

For R-2R Ladder 8-bit DAC,the output voltage is

$V_{o}=\frac{V_{R}}{2^{8}}(2^{7}d_{7}+2^{6}d_{6}+2^{5}d_{5}+2^{4}d_{4}+2^{3}d_{3}+2^{2}d_{2}+2^{1}d_{1}+2^{0}d_{0})$

For input '

VR V. (128 *1 +64 1 + 32 *1 + 16 *1 +8*1+4*1 +2*1+1* 1) 256
  
VR V. * 255 256

$5.10=\frac{V_{R}}{256} *255$

$V_{R}=\frac{256*5.10}{255}$

$V_{R}=5.12V$

For input

$V_{o}=\frac{V_{R}}{256}(128*0+64*1+32*1+16*1+0*8+0*4+1*2+0*1)$

$V_{o}=\frac{5.12}{256}*114$

$V_{o}=2.28V$