[time-nuts] Achieving maximum performance when driving 5370A/B inputs

Bob Camp lists at rtty.us
Sun Feb 28 02:00:30 UTC 2010


Hi

Which *still* carefully avoids the issue of how .....

Bob


On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote:

> Oops! a small correction (2nd paragraph):
> 
> For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum.
> An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance).
> An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance).
> 
> For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum.
> An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance).
> An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance).
> 
> Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance.
> This avoids having to adding an external 5V 50 ohm driver that some would use.
> 
> Bruce
> 
> Bob Camp wrote:
>> Hi
>> 
>> So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place  and was just about to ask about how best to use it.
>> 
>> Hmmmm.......
>> 
>> Bob
>> 
>> 
>> On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote:
>> 
>>   
>>> The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea.
>>> 
>>> For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum.
>>> An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance).
>>> An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance).
>>> 
>>> For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum.
>>> An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance).
>>> An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance).
>>> 
>>> Bruce
>>> 
>>> <5370ATriggering.png><5370BTriggering.png>_______________________________________________
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>> 
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> 
> 
> 
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