RE46C162 Datasheet, PDF (12/22 Pages) Microchip Technology – CMOS Ionization Smoke Detector ASIC with Interconnect, Timer Mode and Alarm Memory

RE46C162/163
3.8 Alarm Memory
If a detector has entered a local alarm, once it exits the
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 3.3 seconds apart. This pattern
will repeat every 40 seconds. The duration of the flash
is 10.5 ms. In order to conserve battery power, this
visual indication will stop after a period of 24 hours. The
user will still be able to identify a unit with an active
alarm memory by pressing the push-to-test button.
When the push-to-test button is active, the horn will
chirp for 10.5 ms every 250 ms.
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.
3.9 Tone Select
The TONE pin selects the NFPA72 temporal horn tone
(high), or the 2/3 duty cycle continuous tone (low). If
this pin is externally connected high, use a current
limiting resistor of at least 1.5K from TONE pin to V_DD.
3.10 Reverse Battery Protection
The RE46C162/163 internally limits the current from
V_SS to V_DD in the event of accidental polarity reversal.
If an input is connected to V_DD it should be done
through a resistance of at least 1.5K to limit the reverse
current through this path.
Standby Mode; No Low Bat tery; No Alarm
Alarm; No Low Battery
Alarm; Low Battery
No Alarm; Low Battery
Oscillator
Inte rnal Clock
LED
P in 15 > Pin 13
T_PER1
T_PW
24 Cloc k Cyc les (40 S)
Pin 13 > Pin 15; 130mV Level Shift on P in 13
T_PER2
24 Cloc k Cy cles (1S)
Pin 15 > Pin 13
Sample Smoke
Horn
IO (Pin 2) as Output
See F igure Below for C omplete Horn Cycle
T_IODLY1
Timing not same scale as above
Low Battery Warning Chirp
IO Charge Dump
IO ( Pin 2) a s Input
T_IOFILT
Horn Start of horn tem poral pattern is not sy nc hroniz ed to an ex ternal alarm
T_IODLY2
T_IODMP
LED supress ed in remote alarm mode
Horn pattern not self completing for external alarm,s ee timing below for complete horn c ycle
Inte rnal Clock
Note s:
1. Smoke is not sampled when the ho rn is active. Horn cycle is self completing in local alarm.
2. L ow battery warnin g chirp is suppressed in local or re mote alarm
3. IO Dump active on ly in loca l alarm, inactive if external alarm
T_HON1 T_HOF1
T_HOF2
Complete Temporal Horn Pattern
Non -Temporal Horn Pattern
T_HON3
T_HOF3
FIGURE 3-1:
Timing Diagram – Standby, Local Alarm, Low Battery.
DS22245A-page 12
 2010 Microchip Technology Inc.