Answers Database
CPLD : XC9500XL: What is bus-hold circuit?
Record #5175
Product Family: Hardware
Product Line: 9500
Product Part: 9500
Problem Title:
CPLD : XC9500XL: What is bus-hold circuit?
Problem Description:
Urgency: Standard
General Description:
What is the "Bus-Hold" circuit, and how can you use it?
Solution 1:
The bus-hold or the keeper circuit is a new architectural
feature that was added in the XC9500XL devices; it is not
available in the XC9500 devices. This circuit exists in the
IOB structure and it is used to hold the last known state of I/O
until the next I/O value is available.
This bus-hold circuit is always enabled during normal operation.
The bus-hold circuit acts as a weak keeper on the I/O pins
all of the times except the following situations:
-Device is blank.
-During power-up/configuration cycle.
-During the INTEST command.
-When the device is in ISP mode.
End of Record #5175 - Last Modified: 12/29/99 18:52 |
