SP504AN Datasheet, PDF (5/11 Pages) Sipex Corporation – Application Note

The tri-state enable and disable timing must be
considered. Given two systems, each config-
ured in DTE/DCE operation, containing two
SP504’s each, System 1 is the DTE, and
System 2 is the DCE. Assume System 1 is now
configured to a DCE and System 2 is config-
ured to a DTE; the two SP504 devices within
each system will have to switch states. If
System 1 switches to DCE before System 2
tri-states its driver, the bus will share driver
outputs until System 2 switches to DTE, thus
causing bus contention problems. In both
systems, the active SP504 should be tri-stated
first before enabling the tri-stated SP504. Al-
though the bus contention will not damage the
SP504 devices, it should be avoided to prevent
short circuit currents at the driver outputs.
One last consideration for DTE/DCE hookup is
the charge pump capacitors. Many have in-
quired about sharing the 22µF caps. For a mini-
mal requirement, the C1 and C2 capacitors must
be separate for each SP504 device. Although
this can be functionally done, Sipex does not
recommend this practice. Please be aware that
if one SP504 becomes nonfunctional, it can
affect the other SP504 as well.
SP504AN
SP504 Application Note
5
© Copyright 2000 Sipex Corporation