Dajgoro wrote:
BigDumbDinosaur wrote:
Dajgoro wrote:
Can anyone recommend a schottky diode model that is easily obtainable and affordable in large quantities?
I prefer trough hole for now.
Edit: I need the drives for tristating the bus too, so I can have another device access the bus.
Please see attached for a suggestion.
Attachment:
The attachment 74s1053_schottky_array_16.pdf is no longer available
Nice, but looking on ebay they tend to be a bit expensive.
Is there an electronics distributor in your area that might be able to get it for you at a more reasonable cost?
An alternative would be to use Thevenin termination, which is just a bunch of resistors. The 74ABT245 transceivers you are using can source 32ma and sink 64ma, which gives you some leeway in choosing appropriate resistor values. For a start, I would try 220 ohms from the '245 outputs up to Vcc and 330 ohms from the '245 outputs to ground. That combination would produce a characteristic impedance of around 100 ohms on each signal.
You could use discrete resistors (1/4 watt carbon film recommended) or a resistor array. I use the latter on my SCSI host adapter for bus termination.
Attachment:
File comment: Resistor Array
4100r_array_bourns.pdf [218.85 KiB]
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Attachment:
File comment: Resistor SIPs
resistor_array_bourns_4300Rseries.pdf [210.63 KiB]
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File comment: Resistor SIPs
resistor_array_bourns_4600Rseries.pdf [235.14 KiB]
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Attachment:
File comment: Some transmission line termination theory.
transmission_line_terminations.pdf [314.95 KiB]
Downloaded 65 times
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