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SVS Operation
6-4
Supply Voltage Supervisor
6.2 SVS Operation
The SVS detects if the AV
CC
voltage drops below a selectable level. It can be
configured to provide a POR or set a flag, when a low-voltage condition occurs.
The SVS is disabled after a brownout reset to conserve current consumption.
6.2.1 Configuring the SVS
The VLDx bits are used to enable/disable the SVS and select one of 14
threshold levels (V
(SVS_IT−)
) for comparison with AV
CC.
The SVS is off when
VLDx = 0 and on when VLDx > 0. The SVSON bit does not turn on the SVS.
Instead, it reflects the on/off state of the SVS and can be used to determine
when the SVS is on.
When VLDx = 1111, the external SVSIN channel is selected. The voltage on
SVSIN is compared to an internal level of approximately 1.2 V.
6.2.2 SVS Comparator Operation
A low-voltage condition exists when AV
CC
drops below the selected threshold
or when the external voltage drops below its 1.2-V threshold. Any low-voltage
condition sets the SVSFG bit.
The PORON bit enables or disables the device-reset function of the SVS. If
PORON = 1, a POR is generated when SVSFG is set. If PORON = 0, a
low-voltage condition sets SVSFG, but does not generate a POR.
The SVSFG bit is latched. This allows user software to determine if a
low-voltage condition occurred previously. The SVSFG bit must be reset by
user software. If the low-voltage condition is still present when SVSFG is reset,
it will be immediately set again by the SVS.