Answers Database
CPLD: XC9500: Device fails to erase when used in an embedded or ATE environment
Record #3653
Product Family: Hardware
Product Line: 9500
Product Part: 9500
Problem Title:
CPLD: XC9500: Device fails to erase when used in an embedded or ATE environment
Problem Description:
Urgency: Standard
General Description:
XC9500 devices fail to ERASE when the SVF/XSVF files are used in
an embedded system or in an ATE environment.
Solution 1:
The erase time required by all XC9500 devices is 1.3 seconds.
This time can be extended in the presence of any or all the
following situations:
(a) low or noisy SYSTEM Vcc - typically a Vcc at or above 5V
is required. The Vcc connections must have adequate
decoupling at each device.
(b) Excessive SYSTEM ground noise - a solid ground signal is
required to ensure effective operation of the internal charge
pumps.
(c) Inaccurate implementation of the wait time procedure -
ideally the wait time should be implemented independent of
TCK. Preferably it should be implemented as a wait time
dependent on an internal independent clock for best accuracy.
JTAGProgrammer can sometimes compensate for these situations
because in its interactions with the system it can determine
that the devices need longer to erase and adjust the value as
appropriate.
SVF files, since they are statically generated, do not have
that luxury of being able to interact with the system and
modify their behavior as appropriate.
Note: Bumping up the ERASE times to 3 seconds should be enough.
End of Record #3653 - Last Modified: 12/14/99 09:10 |
