Answers Database
XPLA1: CoolRunner startup current or high current demands.
Record #7637
Product Family: Hardware
Product Line: R3000
Product Part: R3032
Problem Title:
XPLA1: CoolRunner startup current or high current demands.
Problem Description:
Urgency: Standard
General Description: The XPLA1 CPLD does not seem to start up on a
low current (high impedance) supply. Are there any times that the CPLD
requires a higher level of current?
Solution 1:
There are two distinct times that the XPLA1 devices require a higher
amount of current to start.
During power up, the CPLD monitors the level of VDD. At approximately
2.4Volts, the device recognizes that it has enough voltage to sustain
operation, and it enters a configuration and reset mode. This requires
about 50mA to 100mA for a short period of time (typically 20us or so). If
this initial power is not available for startup, the device will not configure
properly and will draw a higher amount of current for a sustained period
of time. The part may also self heat and resemble a 'latched' part.
The CPLD also requires a larger amount of current (10mA to 100mA)
during ISP operations. Program and verify require a significant amount
of current to correctly perform their operations.
End of Record #7637 - Last Modified: 10/11/99 16:14 |
