RE46C165 Microchip Technology Inc., RE46C165 Datasheet - Page 14

• Manufacturer Part Number: RE46C165
• Description: Cmos Photoelectric Smoke Detector Asic With Interconnect, Timer Mode And Alarm Memory
• Manufacturer: Microchip Technology Inc.

RE46C165/6/7/8
3.6
In standby, an internal reference is compared to the
voltage divided V
latched at the conclusion of the LED pulse. The horn
will chirp once for 10 ms every 43 seconds, until the
low battery condition no longer exists. The low battery
chirp occurs next to the LED pulse.
The low battery notification does not sound in a local or
remote alarm condition.
3.7
In standby, a chamber test is also performed every
43 seconds, by switching to the high gain capacitor C1
and
reflections. Two consecutive chamber test failures will
cause the horn to chirp 3 times for 10 ms spaced
323 ms apart. This will repeat every 42 seconds, as
long as a chamber test fail exists. The failed chamber
test chirps occur ~21 seconds after the LED pulse in
Standby mode (not hush).
The chamber fail notification does not sound in a local
or remote alarm condition.
3.8
If resistors R
figure) are in place and a high-to-low transition occurs
on the TEST input, the device enters a timer mode
(10 minutes maximum for RE46C165/6 devices,
1 minute maximum for RE46C167/8). In this mode, the
smoke comparator reference is switched from the
internal V
appears on VSEN. This allows the sensitivity to be
modified for the duration of the timer period. High gain
operations (push-to-test and chamber test) always use
the internal V
performed in Timer mode.
If VSEN is left unconnected or tied to V
Timer mode operation is inhibited.
If the smoke level causes the reduced sensitivity set
point to be exceeded during this timer period, the unit
will go into a local alarm condition, the horn will sound,
and the Timer mode is cancelled. If an external only
alarm occurs during the Timer mode, the Timer mode
is cancelled.
If the test button is pushed in a standby, reduced
sensitivity mode, the unit is tested normally. Upon
release of the test button, the 10 minute maximum
timer mode counter is reset and restarted.
DS22251A-page 14
sensing
Low Battery Detection
Chamber Fail Detection
Timer Mode
DD
ADJ1
DD
– 3.5V reference to the voltage that
– 3.5V reference. The chamber test is
the
and R
DD
supply. A low battery status is
photo
ADJ2
(see Typical Application
chamber
SS
background
, the Hush
3.9
If a detector has entered a local alarm, when exiting
that local alarm, the alarm memory latch is set. Initially
the LED can be used to visually identify any unit that
had previously been in a local alarm condition. The
LED will flash 3 times spaced 1.3 seconds apart. This
pattern will repeat every 43 seconds. The duration of
the flash is 10 ms. In order to conserve battery power,
this visual indication will stop after a period of 24 hours.
The user will always be able to identify a unit with an
active alarm memory by pressing the push-to-test
button. When this button is active, the horn will chirp
and the LED will pulse on for 10 ms every 250 ms. The
push-to-test alarm will not activate until the alarm
memory is reset.
If the alarm memory condition is set, any time the push-
to-test button is pressed and then released, the alarm
memory latch is reset.
The initial 24 hour visual indication is not displayed if a
low battery condition exits.
3.10
In addition to the normal function of the TEST input, a
special diagnostic mode is available to calibrate and
test the smoke detector. Taking the TEST pin below
V
cycle will enable the diagnostic mode. In the diagnostic
mode, some of the pin functions are redefined. Refer to
Table 3-1
diagnostic mode. In addition, in this mode STROBE is
always enabled, and the IRED is pulsed at the clock
rate of 10 ms nominal.
SS
and sourcing ~200 µA out of the pin for 1 clock
Alarm Memory
Diagnostic Mode
below for redefined pin functions in the
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