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posted by  Rescue me on 10/12/2008 8:56:44 PM  |  status: Live  

Confused. with this aspect.

Course Textbook Chapter Problem
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Question Details:

B. Solve the following questions using Figure 5.4 below. The initial condition of the output Q is
high (H). Hint: Refer to the truth table

(a) Pins for the DC4044 Latch (b) Truth Table for DC4044 the Latch

(a) When /ALM is pushed on, creating a short to ground, what are the input

voltages of S and R, and the output voltage Q?

(b) After (a) happens, /ALM is released. What is the output voltage Q?

(c) After (a) and (b) happen, /RESET is pushed on, creating a short to ground,

what are the input voltages of S and R, and the output voltage Q?

(d) After (a), (b) and (c) happen, /RESET is released. What is the output voltage

Q?

 
 
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(Cramster SME)
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posted by shann(EE-SME) on 10/13/2008 5:43:06 AM  |  status: Live
Asker's Rating: Lifesaver   
Rescue me's comment:
"thanks!"
Response Details:
Given logical circuit diagram
 
   
From this given diagram we can say that logic levels 0 and 1 are equivalent to 0V and 12V.
1. If both ALM and RESET are closed then voltage at S and R equal to 0V. That is logical zero at these pins.
2. If ALM closed and RESET is opened then voltage at S is 0V and at R equal to 12V. That is logical zero at S and logical 1 at R.
3. If ALM opened and RESET is closed then voltage at S is 12V and at R equal to 0V. That is logical 1 at S and logical 0 at R.
4. If both ALM and RESET is opened then voltage at S and R equal to 12V. That is logical 1at S and R.
 
From the given truth table we can write the following statements:
 
(a)
When ALM is pushed, S = 0 and R = 1 output Q = 1.
 
(b)
After (a) happens, /ALM is released, then S = 1 and R = 1   output no change  (i.e. Q = 1)
 
(c)
After (a) and (b) happen, /RESET is pushed on, then S = 1 and R = 0  output Q = 0.
 
(d)
After (a), (b) and (c) happen, /RESET is released, then S = 1 and R = 1 output no change  (i.e. Q = 1)
 
 
I hope this helps you...........................
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