Saturday 4 February 2012

Digital questions - 4

16.  A settable flip-flop's normal starting state when power is first applied to a circuit is always the ________ state.
A. resetB. set
C. toggleD. dual

17.  In the automatic reset circuit for a flip-flop, how long does it take the capacitor to completely charge?
A. 1 time constant (RC)
B. 2 time constants (RC)
C. 5 time constants (RC)
D. 10 time constants (RC)

18.  The output of a standard TTL NAND gate is used to pull an LED indicator LOW. The LED is in series with a 470- resistor. What is the current in the circuit when the LED is on?
A. 7.02 mA
B. 8.51 mA
C. 10.63 mA
D. 5.32 mA

19.  When the inputs to a flip-flop are changing at the same time that the active trigger edge of the input clock is making its transition, this condition is called:
A. racing
B. toggling
C. slave loading
D. pulse timing

20.  Is the propagation delay from the clock to the output for the 7476 the same as the delay from the set or reset to the output?
A. yesB. no

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