A proposed device accepts 5 or 3.3 volts input level and can safely drive up to 8 CMOS (3.3 V) lines and one TTL (5 V) line. The maximum delay on the CMOS line is 16 ns. TTL line delay is 4 ns. I believe it’s Ok for most of the ham radio applications. Also, there is a control LED.
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SN74LVC1G34 is a fast single buffer IC with low-power consumption. This device is tolerant of up to 5.5 input voltage.
The internal 1PPS line is working on the CMOS level, driving two additional SN74LVC1G34 for LED and TTL output. Those buffers are powered from the 5 V source.
The primary CMOS buffer IC is SN74HC244. This is an eight-channel buffer with high-current outputs. On-board regulator provides 3.3 V.
It’s possible to power the U1 and U4 from the 5 V source and gets all TTL outputs.
This was a one evening build. The device was built on a simple breadboard.
As a 1PPS source, I’m using my GNSS receiver.
The measured propagation delay on TTL output is only 4 ns:
The SN74HC244 buffer is a little bit slower, and the CMOS lines delay is 16 ns:
All channels are working synchronously, with no delays or ringing.
All measures are made with Saleae 8 channel logic analyzer:
Thanks for reading!
5 thoughts on “1PPS distribution circuit”
This device can synchronize clocks for up to 8 operating systems.
In what projects can this be used? Where can you need to synchronize multiple operating systems?
Hello my name is Nico, congratulations on your work. I would like to make a query, do you know or have some diagram of some circuit that allows to apply a selectable delay of 0 to 500ms (that is necessary) to the signal 1pps and to the 10 Mhz. Thanks.
You can use a monostable multivibrator like LT6993-1: https://www.analog.com/media/en/technical-documentation/data-sheets/LTC6993-6993-1-6993-2-6993-3-6993-4.pdf
See page 21 Pulse Delay Generator for example.