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3.3
POWER ON RESET (POR)
When a battery is inserted into the detector, the low battery load will be turned on
and the battery voltage will be measured. If it is less than or equal to 2.7V, the
detector will continue to sample the battery voltage every 1 second until the
voltage is greater than 2.7V. No other action will be taken until that time. This
prevents a used battery from being installed and generating a low battery trouble
shortly thereafter. Once the battery voltage is confirmed to be greater than 2.7V,
normal operation of the gas detector begins. During POR the detector wait
approximately 30 seconds for the gas cell to stabilize, and during this time both
LED's blink once every ten seconds, but the gas cell is not sampled.
3.4
BROWN OUT RESET (BOR)
In the event of a battery removal, the microcontroller features a brown out reset
(BOR). This feature will prevent the microcontroller from running astray. The
BOR feature includes a hysteresis. Once power has been reapplied, the detector
will power up using the standard POR sequence.
3.5
CELL SUPERVISION
The gas cell cannot be supervised for sensitivity, but is supervised for open
circuit faults once every minute. If a fault condition is detected, the detector is in
trouble. In trouble, the red LED will flash once every 5 seconds, and the sounder
will chirp once every 45 seconds, and Status A will be set low, and Status B will
be set high. Cell trouble is non-latching. Cell supervision will preempt a low
battery condition, and will be preempted by an alarm condition.
3.6
CO ALARM
When the detector enters a CO alarm, both output pins 1 and 3 will be set low.
The piezo is operated at 3.3kHz with the temporal 4 sound pattern per UL2034.
The sound pressure level shall meet a minimum of 85dBA @ 10 ft per UL2034 /
UL2075. The green LED will turn off, while the red LED will flash at the increased
rate of approximately 10ms every 1 second. The alarm is non-latching. When the
CO level returns to a normal level, the horn will stop sounding, the LEDs will
return to the state in accordance with the state of the detector. CO Alarm will
preempt both low battery and cell trouble.
3.7
TEST SWITCH
The test switch can be used to check the functionality of the circuitry. If the
detector is not in a trouble mode or end of life and the test switch is depressed
for 1 second, the green LED will turn off while the red LED will flash once per
second. Simultaneously, the alarm status pins 1 and 3 will be pulled low. If the
test button remains depressed for more than 3 seconds, the built in piezo will
sound with the temporal 4 pattern per UL 2034 / UL 2075. When the test switch
is released, the LED and piezo will return to the standby mode (within 0.5
seconds max.). If the detector is in a trouble mode and the test switch is
depressed, the test switch will be ignored.
LINEAR LLC
FCC ID: EF4 SST00116
SECTION 3
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