How Many Clock Pulses Are Counted for Different Input Voltages in an ADC System?

[mym786]

Homework Statement

The Analog-To-Digital Converter “ADC” system shown in Fig. 1 uses 1 MHZ clock generator and a ramp voltage that increases from 0V to 1.25 V in a time 125 ms.
Determine the number of clock pulses counted into the register
when Vi=0.9 V
and when it is 0.75 V

Homework Equations

The Attempt at a Solution

VR = 1.25 v TR =125 ms
Vi=0.9 V
t1= tr/Vr * Vi = 125ms *0.9 V / 1.25 V = 90 ms
T= 1/f = 1/ 1 Mz = 1μs
N = t1 / T = 90 ms / 1 μs =900
Vi=0.75 V
t1= tr/Vr * Vi = 125 ms *0.75 V / 1.25 V = 75 ms
N = t1 / T = 75 ms / 1 μs =750*




This is the solution of the problem by my prof. My question why N = 90ms/1μs = 900 and NOT 90000 ? The same goes for 750.

Thank you very much.

 

[berkeman]

Homework Statement

The Analog-To-Digital Converter “ADC” system shown in Fig. 1 uses 1 MHZ clock generator and a ramp voltage that increases from 0V to 1.25 V in a time 125 ms.
Determine the number of clock pulses counted into the register
when Vi=0.9 V
and when it is 0.75 V

Homework Equations

The Attempt at a Solution

VR = 1.25 v TR =125 ms
Vi=0.9 V
t1= tr/Vr * Vi = 125ms *0.9 V / 1.25 V = 90 ms
T= 1/f = 1/ 1 Mz = 1μs
N = t1 / T = 90 ms / 1 μs =900
Vi=0.75 V
t1= tr/Vr * Vi = 125 ms *0.75 V / 1.25 V = 75 ms
N = t1 / T = 75 ms / 1 μs =750*




This is the solution of the problem by my prof. My question why N = 90ms/1μs = 900 and NOT 90000 ? The same goes for 750.

Thank you very much.

I get the same answers as you. A 1MHz clock has a 1us period.

 

[Char. Limit]

I get the same answers as you. A 1MHz clock has a 1us period.

The number of pulses I get is 112 bpm, but that's not important now. The division really should give 90000 as a result, not 900.

 

[berkeman]

The number of pulses I get is 112 bpm, but that's not important now. The division really should give 90000 as a result, not 900.

You just finish working out? My pulse was near that at the end of a 200m IM at noon

Oops, [/hijack]