PIC16LF18854 Datasheet, PDF (302/668 Pages) Microchip Technology – C Compiler Optimized RISC Architecture

PIC16(L)F18856/76
20.10 Auto-Shutdown
Auto-shutdown is a method to immediately override the
CWG output levels with specific overrides that allow for
safe shutdown of the circuit. The shutdown state can be
either cleared automatically or held until cleared by
software. The auto-shutdown circuit is illustrated in
Figure 20-12.
20.10.1 SHUTDOWN
The shutdown state can be entered by either of the
following two methods:
• Software generated
• External Input
20.10.1.1 Software Generated Shutdown
Setting the SHUTDOWN bit of the CWGxAS0 register
will force the CWG into the shutdown state.
When the auto-restart is disabled, the shutdown state
will persist as long as the SHUTDOWN bit is set.
When auto-restart is enabled, the SHUTDOWN bit will
clear automatically and resume operation on the next
rising edge event.
20.10.2 EXTERNAL INPUT SOURCE
External shutdown inputs provide the fastest way to
safely suspend CWG operation in the event of a Fault
condition. When any of the selected shutdown inputs
goes active, the CWG outputs will immediately go to the
selected override levels without software delay. Several
input sources can be selected to cause a shutdown con-
dition. All input sources are active-low. The sources are:
• Comparator C1OUT_sync
• Comparator C2OUT_sync
• Timer2 – TMR2_postscaled
• Timer4 – TMR4_postscaled
• Timer6 – TMR6_postscaled
• CWGxIN input pin
Shutdown inputs are selected using the CWGxAS1
register (Register 20-6).
Note:
Shutdown inputs are level sensitive, not
edge sensitive. The shutdown state can-
not be cleared, except by disabling auto-
shutdown, as long as the shutdown input
level persists.
20.11 Operation During Sleep
The CWG module operates independently from the
system clock and will continue to run during Sleep,
provided that the clock and input sources selected
remain active.
The HFINTOSC remains active during Sleep when all
the following conditions are met:
• CWG module is enabled
• Input source is active
• HFINTOSC is selected as the clock source,
regardless of the system clock source selected.
In other words, if the HFINTOSC is simultaneously
selected as the system clock and the CWG clock
source, when the CWG is enabled and the input source
is active, then the CPU will go idle during Sleep, but the
HFINTOSC will remain active and the CWG will con-
tinue to operate. This will have a direct effect on the
Sleep mode current.
DS40001824A-page 302
Preliminary
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