[time-nuts] Trimble Thunderbolt 1pps
Javier Herrero
jherrero at hvsistemas.es
Mon Jan 27 10:35:23 EST 2014
On 27.01.2014 15:08, Attila Kinali wrote:
>> In practice, the receiver chip only has one power supply. It would take
>> extra work to make the switching threshold below ground.
> That's not correct. Standard transceiver chips (like the MAX232 family)
> have an integrated charge pump to get a negative power supply.
>
Hello,
The venerable MC1489 does not need a negative supply, and can have a
threshold below ground, without too much complication.
http://www.onsemi.com/pub_link/Collateral/MC1489-D.PDF (the receiver
circuit diagram is shown)
On the other side, the MAX232 has positive thresholds in the receiver
side http://datasheets.maximintegrated.com/en/ds/MAX220-MAX249.pdf pag. 6
Regards,
Javier
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