25.02.2013 Views

Voltage References

Voltage References

Voltage References

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

TTL<br />

5 "off" drivers (@0.06 U.L each),<br />

+8 receivers (@ 1.0 U.L each) = 8.3 Unit Loads<br />

RT = 120 Q at each end of the cable.<br />

MC75172B, MC75174B<br />

Figure 18. Typical EIA-485 System<br />

TTL<br />

TTL TTL<br />

NOTES:<br />

1) Terminating resistors RT must be located at the physical ends of the cable.<br />

2) Stubs should be as short as possible.<br />

3) Circuit ground of all drivers and receivers must be connected via a dedicated wire within the cable.<br />

Do not rely on chassis ground or power line ground.<br />

TTL<br />

TTL<br />

TTL<br />

TTL<br />

TTL<br />

TTL TTL<br />

MOTOROLA LINEAR/INTERFACE ICs DEVICE DATA<br />

7-191<br />

120Q<br />

Twisted<br />

Pair

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!