hi there, i'm doing a IC tester and it is able to only input high and low voltages to the Input pin of the IC. For example, for a Inverted NOT IC, when i input high, it will output low. However, what input should i set for the CLK input pin of 74 series IC such as 74LS73A (flip-flop)? An additional osscilator?And what does it meant by "negative going edge of pulse"?. It is not high or low voltage,but the transition from high to low with time equivalent with one high or low signal, am i right?
I would have thought the datasheet would explain it, with some sort of table showing the states of the device. I just checked, the TI book does have such a table.
Or, one could get an actual 7473 flip flop and put it in a breadboard. Put some LEDs on the output, and then play around with different combinations on the input. Do it enough times, and the poster(s) will build up such a table.
The clock is used to syncronize. The clock is used so that when the clock goes on then the circuit will "compute" its output. That is, when the clock is in the "off" state it gives time for the device to do the computation and have a stable output. You basically trigger the circuitry inside the component to start the "computation" and it takes so long. You know the maximum time it takes and this is the smallest time the clock can then turn back off(or on depending how you look at it).
So in a clock you basically have 2 states. When the clock is "off" this means that the computation is taking effect and the output is not ready. When the clock goes on this means the output is ready and you can get the information off the output and it will be correct.
Now this can happen in two ways. You can use voltage state to tell you the state of the clock or the edges. (Sometimes its easier with the edges for specific reasons)
Suppose you want to do your flip flop. You put your signal on the input. Now if its a synchronous ff it will not have a correct output. You have to trigger the clock so that the "computation" will take place. In this case it doesn't matter which type of clock you use and doesn't matter how many pulses but you need to make sure you sample the clock when it is on.
I'll leave you to figure out how to convert a synchronous flip flop to an asynchronous flip flop. Obviously you have to somehow use the clock pin when the signal changes. If you have a seperate digital control line you can just use that on the clock and control the clock directly. Its best to play around with the thing and see how it works before you try and build something that actually uses it.
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