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Improve rise time on monostable multivibrators?

J

Jason

Jan 1, 1970
0
I'm building a circuit that uses a few monostables (LS123's) to
generate pulses. The resulting pulses end up with about 100 ns rise
time, and I need to get this down to 15 ns. Any ideas on how I can do
that?
 
T

Tim Wescott

Jan 1, 1970
0
Jason said:
I'm building a circuit that uses a few monostables (LS123's) to
generate pulses. The resulting pulses end up with about 100 ns rise
time, and I need to get this down to 15 ns. Any ideas on how I can do
that?

* Use a faster technology, such as a 74VHC123.
* Minimize the load capacitance on the pin.
* If you can sacrifice fall time and power consumption, use a pullup.
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Jason <[email protected]>
I'm building a circuit that uses a few monostables (LS123's) to
generate pulses. The resulting pulses end up with about 100 ns rise
time, and I need to get this down to 15 ns. Any ideas on how I can do
that?

Stop using the LS family.
 
J

John Larkin

Jan 1, 1970
0
I'm building a circuit that uses a few monostables (LS123's) to
generate pulses. The resulting pulses end up with about 100 ns rise
time, and I need to get this down to 15 ns. Any ideas on how I can do
that?

I'm surprised that any LS part would be that slow. I thought they were
in the 7 ns Tr/Tf range. The simpler gates had typ prop delays of 8
ns.

People don't make one-shots much any more; they've fallen out of
favor.

John
 
J

Joerg

Jan 1, 1970
0
Hi Jason

One method would be to simply hang a fast Schmitt trigger onto the
output. If you use an LVDS chip you could achieve ramp times under
1nsec. But I believe the LS' jitter will cause this ramp to meander
around quite a bit.

Regards, Joerg
 
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