Datasheet

3.4.1 General Rail Windows Selections
3.4.2 Sequencing Conditions Selections
3.4.3 Alarm Actions
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• Active Low (Polarity)—specify enable pin polarity.
• UV/OV Threshold—specify undervoltage and overvoltage trip points. Note that UV values of zero
essentially cause the device to ignore any undervoltage conditions and that OV values which are
excessively high cause the device to ignore any overvoltage conditions.
• Out of Reg Time (ms)—specify the maximum amount of time (or glitch width) that the rail can be out
of the UV/OV range before an alarm is declared.
• Max Time for Regulation (ms)—specify the maximum amount of time a rail is allowed to achieve
regulation (rail voltage must be within the UV/OV range) before an alarm is declared.
• Ignore Glitch Alarms— masks glitches from the Error Log window.
• Log Errors to Flash—log rail errors to nonvolatile memory for later evaluation.
• Sequence After Shutdown—specify the UCD9081 ENx and GPOx output to be marked to
resequence the system (as defined by the current sequencer configuration) if they are specified as a
dependency in the DependencyMasks register.
• Voltage Divider—specify the user rail voltage divider values. The GUI uses these values to properly
scale and display the voltages received through the UCD9081 monitors. Note that zero value divider
resistor values cause the divider ratio to be evaluated as unity (no scaling).
• Store to Buffer and Close Buttons—The Store to Buffer button saves the current window entries to a
GUI buffer and the Close button closes the window without saving the form entries.
Voltage rail sequencing conditions are:
• None—rail is not sequenced.
• Time—number of milliseconds before this rail is enabled.
• Parent (Reg)—number of milliseconds to delay after the parent rail achieves regulation before
enabling this rail.
• Parent (V)—voltage at which the parent rail must be before this rail is enabled
The alarm actions are:
• Ignore— glitch or alarm events are ignored by the device.
• Log Only— alarm events are logged only by the device (i.e., no action taken).
• Retry—continue to retry a configurable number of times (n = 0,1,2,3,4), then shut down.
• Retry Continuously—when an error on the selected rail happens, a retry occurs. A retry is an attempt
by the UCD9081 to restart the corresponding power supply by disabling the rail (with ENx pin) and
then reenabling the rail. This repeats until the power supply rail alarm clears.
• Sequence—when an error occurs on this rail, resequence the system according to the current
sequencer configuration.
• Rails/GPOs to Shutdown—allows the user to specify which set of rails and GPOs are part of a
shutdown event. This is only enabled when a Retry is selected (Retry 0-4).
SLVU249 – September 2008 UCD9081 Power Supply Sequencer and Monitor EVM 11
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