Up/Dn Counter Behavior - CD74HC193

Stephen Tomporowski

Other Parts Discussed in Thread: CD74HC193

The application is a presetable count-down timer for a bomb fuze. So, to put it mildly, timing is important. The question is about the behavior of the /TCD output during load. If you load all zeros into the CD74HC193, does /TCD immediately go low and then clock high at the next clock pulse? This would be set up for clocking down.

Thanks...Steve

over 8 years ago

0 Cameron Phillips over 8 years ago

TI__Genius 12410 points

Stephen,

I will test this and get back to you.

Thank you,
Cameron

0 Stephen Tomporowski over 8 years ago in reply to Cameron Phillips

Prodigy 220 points

Thanks.

However, I was looking at the timing diagrams and reading the text in the datasheet. /TCD goes low one clock pulse before zero count so that the edges line up. This probably means that you need that clock pulse for /TCD to go low, meaning that if you load the counter with all zeros, /TCD will stay high.

Let's see if I'm right....;-)

Logic

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Up/Dn Counter Behavior - CD74HC193