R&E International
A Subsidiary of Microchip Technology Inc.
RE46C129
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
General Description
The RE46C129 is low power CMOS ionization type
smoke detector IC. With few external components this
circuit will provide all the required features for an
ionization type smoke detector.
An internal oscillator strobes power to the smoke
detection circuitry for 10.5mS every 1.66 seconds to
keep standby current to a minimum. A check for a low
battery condition is performed every 40 seconds when
in standby.
An interconnect pin allows multiple detectors to be
connected such that when one units alarms all units will
sound.
Although this device was designed for smoke detection
utilizing an ionization chamber it could be used in a
variety of security applications.
The RE46C129 is recognized by Underwriters
Laboratories for use in smoke detectors that comply
with specification UL217 and UL268.
Features
•
•
•
•
•
•
•
•
•
•
•
Guard Outputs for Ion Detector Input
+/-0.75pA Detect Input Current
Internal Reverse Battery Protection
Low Quiescent Current Consumption (<6.5uA)
Available in 16L PDIP or 16L N SOIC
ESD Protection on all Pins
Internal Low Battery Detection
Interconnect up to 40 Detectors
Compatible with Allegro A5350
UL Recognized per File S24036
Available in Standard Packaging or RoHS
Compliant Pb Free Packaging.
Pin Configuration
NC
IO
LBADJ
NC
LED
VDD
RBIAS
FEED
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GUARD2
DETECT
GUARD1
VSEN
OSCAP
HS
HB
VSS
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply Voltage
Input Voltage Range Except FEED, IO
FEED Input Voltage Range
IO Input Voltage Range
Reverse Battery Time
Input Current except FEED
Operating Temperature
Storage Temperature
Maximum Junction Temperature
SYMBOL
V
DD
V
in
V
infd
V
io1
T
RB
I
in
T
A
T
STG
T
J
VALUE
15
-.3 to V
dd
+.3
-10 to +22
-.3 to 17
5
10
-10 to 60
-55 to 125
150
UNITS
V
V
V
V
S
mA
°C
°C
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are
stress ratings only and operation at these conditions for extended periods may affect device reliability.
This product utilizes CMOS technology with static protection; however proper ESD prevention procedures should be used
when handling this product. Damage can occur when exposed to extremely high static electrical charge.
© 2009 Microchip Technology Inc.
DS22172B-page 1
RE46C129
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
DC Electrical Characteristics at TA = 25°C, VDD=9V, OSCAP=.1uF, RBIAS=8.2MΩ, VSS=0V (unless
otherwise noted)
Test
Pin
6
6
6
8
2
8
2
15
15
8
15
15
8
2
5
10,11
10,11
5
2
2
2
6
3
14,15
15,16
13,15
14,15
13,15
14,16
Guard Amplifier
Guard Amplifier
Smoke Comparator
Guard Amplifier, Note 2
Smoke Comparator, Note 2
Guard Amplifier Outputs, Note 2
Parameter
Supply Voltage
Supply Current
Symbol
V
DD
I
DD1
I
DD2
V
IH1
V
IH2
V
IL1
V
IL2
IL
DET1
IL
DET2
IL
FD
Test Conditions
Operating
RBIAS=8.2MΩ, OSCAP=.1uF
RBIAS=8.2MΩ, OSCAP=.1uF;Vdd=12V
Min
6
Limits
Typ
Max
12
4
6.5
9
Units
V
uA
uA
V
V
Input Voltage High
FEED Input
No Local Alarm, IO as an Input
FEED Input
No Local Alarm, IO as an Input
VDD=9V, DETECT=VSS, 0-40% RH
VDD=9V, DETECT=VSS, 85% RH
Note 1
FEED=-10V
VDD=9V, DETECT=VDD, 0-40% RH
VDD=9V, DETECT=VDD, 85% RH
Note 1
FEED=22V
No Alarm, Vio=17V
Outputs Off
IOH=-16mA, VDD=7.2V
IOL=16mA, VDD=7.2V
IOL=10mA, VDD=7.2V
No Alarm, Vio=Vdd-2V
Alarm, Vio=Vdd-2V or Vio=0V
At Conclusion of Local Alarm or Test,
Vio=1V
T
A
=-10 to 60ºC, Note 3
6.3
3
2.7
1
-0.75
-1.50
-50
0.75
1.50
50
150
1
6.3
.9
1
25
-4
5
7.2
-50
-50
-50
2
.5
Input Voltage Low
V
V
pA
pA
uA
pA
pA
uA
uA
uA
V
V
V
uA
mA
mA
Input Leakage Low
Input Leakage High
IH
DET1
IH
DET2
IH
FD
I
IOL2
Output Off Leakage High
Output High Voltage
Output Low Voltage
I
IOHZ
V
OH1
V
OL1
V
OL3
I
IOL1
I
IOH1
I
IODMP
Output Current
100
-16
Low Battery Voltage
Internal Sensitivity Set Voltage
Offset Voltage
V
LB
V
SET2
VG
OS1
VG
OS2
VG
OS3
7.5
65.5
7.8
50
50
50
V
DD
-.5
V
DD
-2
V
%V
DD
mV
mV
mV
V
V
kΩ
Common Mode Voltage
V
CM1
V
CM2
Z
OUT
Output Impedance
10
Note 1: Sample test only
Note 2: Not 100% production tested
Note 3: Production test at room with temperature guardbanded limits.
© 2009 Microchip Technology Inc.
DS22172B-page 2
RE46C129
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
AC Electrical Characteristics at TA = 25°C, VDD=9V, OSCAP=.1uF, RBIAS=8.2MΩ, VSS=0V (unless
otherwise noted)
Test
Pin
12
12
5
5
5
5
10,11
10,11
10,11
10,11
2
2
2
2
Parameter
Oscillator Period
Symbol
T
PER1
T
PER2
T
PW
T
LON
T
LOF1
T
LOF2
T
HON1
T
HON2
T
HOF1
T
HOF3
T
IODMP
T
IODLY1
T
IOFILT
T
IODLY2
Test Conditions
No Alarm Condition
Alarm Condition
Operating
Operating
Standby, No Alarm
Alarm Condition
Operating, Alarm Condition
Low Battery, No Alarm
Operating, Alarm Condition
Low Battery, No Alarm
At Conclusion of Local Alarm or Test
From Start of Local Alarm to IO Active
IO pulse width guaranteed to be filtered.
IO as Input, No Local Alarm
No Local Alarm, IO as input, From IO
active to Horn Active
Min
1.34
37.5
9.4
9.4
32
.8
141
9.4
71
32
1.34
Limits
Typ
Max
1.67
41.5
10.5
10.5
40
1
166
10.5
83
40
1.67
3
450
2
45.8
12.9
12.9
48
1.2
190
12.9
95
48
2.0
Units
S
mS
mS
mS
S
S
mS
mS
mS
S
S
S
mS
S
Oscillator Pulse Width
LED On Time
LED Off Time
Horn On Time
Horn Off Time
IO Charge Dump Duration
IO Delay
IO Filter
Remote Alarm Delay
.450
2.2
© 2009 Microchip Technology Inc.
DS22172B-page 3
RE46C129
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Functional Block Diagram
© 2009 Microchip Technology Inc.
DS22172B-page 4
RE46C129
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
DEVICE DESCRIPTION and APPLICATION NOTES
Internal Timing – With external components as indicated on the application drawing the period of the oscillator is
nominally 1.67 seconds in standby. Every 1.66 seconds the detection circuitry is powered up for 10.5mS and the
status of the smoke comparator is latched. In addition every 40 seconds the LED driver is turned on for 10.5mS
and the status of the low battery comparator is latched. The smoke comparator status is not checked during the
low battery test, during the low battery horn warning chirp, or when the horn is on due to an alarm condition.
If an alarm condition is detected the oscillator period increases to 41.5mS. In any alarm condition the horn is on
for 166mS and off for 83mS (typical).
Due to the low currents used in the oscillator the capacitor on pin 12 should be a low leakage type. Oscillator
accuracy will depend mainly on the tolerance of the RBIAS resistor and OSCAP capacitor.
Smoke Detection Circuit – The smoke comparator compares the ionization chamber voltage to a voltage derived
from a resistor divider across VDD. This divider voltage must be provided externally on pin 13 (VSEN). See the
application drawing (FIG 2).
The guard amplifier and outputs are always active and will be within 50mV of the DETECT input to reduce surface
leakage. The guard outputs also allow for measurement of the DETECT input without loading the ionization
chamber.
Low Battery Detection - An internal reference is compared to the voltage divided VDD supply. The battery can be
checked under load via the LED low side driver output since low battery status is latched at the end of the 10.5mS
LED pulse. Pin 3 (LBADJ) can be used to modify the low battery set point by placing a resistor to VDD or VSS.
The transmission switch on LBADJ is turned on during the LED pulse so an external resistance can be added on
pin 3 to modify the set point if desired.
LED Pulse – The LED is pulsed on for 10.5mS every 40S in standby. In alarm the LED is pulsed on for 10.5mS
every 1S.
Interconnect – Pin 2 (IO) provides the capability to common many detectors in a single system. If a single unit
goes into alarm the IO pin is driven high. This high signal causes the interconnected units to alarm. The LED
flashes every 1S for 10.5mS on the signaling unit and is inhibited on the units that are in alarm due to the active
IO signal. An internal sink device on the IO pin helps to discharge the interconnect line. This charge dump device
is active for 1 clock cycle after the unit exits a local alarm condition (1.67S).
The interconnect input has a 500mS nominal digital filter which will filter out pulsed signals on the IO pin. This
allows for interconnection to other types of alarms (carbon monoxide for example) that may have a pulsed
interconnect signal. This filter will eliminate unwanted random horn activations caused by a pulsed (<500ms
nominal) IO input signal.
Testing - By holding pin 12 (OSCAP) low the internal power strobe is active. Functional testing can be
accelerated by driving pin 12 with a 4 kHz square wave however the 10.5mS strobe period must be maintained
for proper operation of the analog circuitry. Please refer to the timing diagrams. All internal timing is reset after a
power up. By holding pins 8 and 12 low, reducing VDD and monitoring Pin 10 the low battery trip level can be
measured at power up.
© 2009 Microchip Technology Inc.
DS22172B-page 5
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