MICROCHIP RE46C122

R&E International
A Subsidiary of Microchip Technology Inc.
RE46C122
CMOS Ionization Smoke Detector ASIC with Interconnect and Timer Mode
Product Specification
General Description
Features
The RE46C122 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. The temporal horn pattern supports the
NFPA 72 emergency evacuation signal.
An interconnect pin allows multiple detectors to be
connected such that when one units alarms all units will
sound.
•
>1500V ESD Protection (HBM) on all Pins
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
Internal Low Battery Detection
Power Up Low Battery Test
Interconnect up to 40 Detectors
10 Minute Timer for Sensitivity Control
Compatible with Allegro A5367
Available in Standard Packaging or RoHS Compliant
Pb Free Packaging.
Pin Configuration
An internal 10 minute timer allows for a separate button
to be used for reduced sensitivity mode.
TSTART
1
16
GUARD2
IO
2
15
DETECT
3
14
GUARD1
4
13
VSEN
LED
5
12
OSCAP
VDD
6
11
HS
RBIAS
7
10
HB
FEED
8
9
LBADJ
Although this device was designed for smoke detection
utilizing an ionization chamber it could be used in a
variety of security applications.
TSTROBE
Utilizing low power CMOS technology the RE46C122
was designed for use in smoke detectors that comply
with Underwriters Laboratory Specification UL217 and
UL268.
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
VALUE
UNITS
VDD
Vin
Vinfd
Vio1
TRB
Iin
TA
TSTG
TJ
15
-.3 to Vdd +.3
-10 to +22
-.3 to 17
5
10
-10 to 60
-55 to 125
150
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.
DS22173A-page 1
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
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)
Symbol
Test
Pin
Supply Voltage
VDD
6
Operating
Supply Current
IDD1
6
RBIAS=8.2MΩ, OSCAP=.1uF
IDD2
6
RBIAS=8.2MΩ, OSCAP=.1uF;Vdd=12V
VIH1
8
VIH2
2
Parameter
Input Voltage High
Input Voltage Low
Input Leakage Low
Input Leakage High
VIH3
1
VIL1
8
VIL2
2
VIL3
1
ILDET1
15
ILDET2
15
ILFD
8
IHDET1
Test Conditions
Min
6
5
6.2
No Local Alarm, IO as an Input
Limits
Typ
Max
Units
12
V
6.5
uA
9
uA
4.5
V
3
V
4.5
V
4.5
2.7
V
1
V
2.5
V
VDD=9V, DETECT=VSS, 0-40% RH
-0.75
pA
VDD=9V, DETECT=VSS, 85% RH
Note 1
-1.50
pA
FEED=-10V
-50
uA
15
VDD=9V, DETECT=VDD, 0-40% RH
0.75
pA
IHDET2
15
VDD=9V, DETECT=VDD, 85% RH
Note 1
1.50
pA
IHFD
8
FEED=22V
50
uA
No Alarm, Vio=17V
150
uA
1
uA
80
uA
No Local Alarm, IO as an Input
IIOL2
2
Output Off Leakage High
IIOHZ
4,5
Outputs Off
Input Pull Down Current
IPD1
1
TSTART=9V
20
Output High Voltage
VOH1
10,11
IOH=-16mA, VDD=7.2V
6.3
Output Low Voltage
VOL1
10,11
IOL=16mA, VDD=7.2V
.9
V
VOL2
4
IOL=500ua
.5
V
VOL3
5
IOL=10mA, VDD=7.2V
1
V
IIOL1
2
No Alarm, Vio=Vdd-2V
25
60
uA
IIOH1
2
Alarm, Vio=Vdd-2V or Vio=0V
-4
-16
mA
IIODMP
2
At Conclusion of Local Alarm or Test,
Vio=1V
5
VLB
6
TA=-10 to 60ºC, Note 3
VSET1
13
VSET2
3
Output Current
Low Battery Voltage
Internal Sensitivity Set Voltage
© 2009 Microchip Technology Inc.
7.2
48.5
50
V
mA
7.5
7.8
V
50
51.5
%VDD
65.5
%VDD
DS22173A-page 2
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
DC Electrical Characteristics – Continued
Parameter
Symbol
Test
Pin
VGOS1
14,15
Guard Amplifier
-50
50
mV
VGOS2
15,16
Guard Amplifier
-50
50
mV
VGOS3
13,15
Smoke Comparator
-50
50
mV
VCM1
14,15
Guard Amplifier, Note 2
2
VDD-.5
V
.5
VDD-2
V
Offset Voltage
Common Mode Voltage
Test Conditions
VCM2
13,15
Smoke Comparator, Note 2
Output Impedance
ZOUT
14,16
Guard Amplifier Outputs, Note 2
Hysteresis
VHYS
13
No Alarm to Alarm Condition
Min
Limits
Typ
Max
10
90
130
Units
kΩ
170
mV
Note 1: Sample test only.
Note 2: Not 100% production tested.
Note 3: Production test at room with temperature guardbanded limits.
AC Electrical Characteristics at TA = 25°C, VDD=9V, OSCAP=.1uF, RBIAS=8.2MΩ, VSS=0V (unless
otherwise noted)
Min
Limits
Typ
Max
12
No Alarm Condition
1.34
1.67
2
S
12
Alarm Condition
37.5
41.5
45.8
mS
Operating
9.4
10.5
12.9
mS
5
Operating
9.4
10.5
12.9
mS
TLOF1
5
Standby, No Alarm
32
40
48
S
TLOF2
5
Alarm Condition
.8
1
1.2
S
TLOF3
5
Timer Mode, No Alarm
8
10
12
S
THON1
10,11
Operating, Alarm Condition, Note 4
450
500
550
mS
THON2
10,11
Low Battery, No Alarm
9.4
10.5
12.9
mS
THOF1
10,11
Operating, Alarm Condition, Note 4
450
500
550
mS
THOF2
10,11
Operating, Alarm Condition, Note 4
1.35
1.5
1.65
S
THOF3
10,11
Low Battery, No Alarm
32
40
48
S
IO Charge Dump Duration
TIODMP
2
At Conclusion of Local Alarm or Test
1.34
1.67
2.0
S
IO Delay
TIODLY1
2
From Start of Local Alarm to IO Active
Symbol
Test
Pin
TPER1
TPER2
Oscillator Pulse Width
TPW
5
LED On Time
TLON
LED Off Time
Parameter
Oscillator Period
Horn On Time
Horn Off Time
IO Filter
Remote Alarm Delay
Timer Period
TIOFILT
2
TIODLY2
2
TTPER
4
Test Conditions
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
No Alarm
3
S
.450
8
Units
10
450
mS
2.2
S
12
Min
Note 4 – See timing diagram for horn temporal pattern.
All timing except for TPER and TPW are guaranteed by functional tests.
© 2009 Microchip Technology Inc.
DS22173A-page 3
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Functional Block Diagram
© 2009 Microchip Technology Inc.
DS22173A-page 4
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
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.
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 is available externally on pin 13 (VSEN). When smoke is
detected this voltage is internally increased by 130mV nominal to provide hysteresis and make the detector less
sensitive to false triggering.
Pin 13 (VSEN) can be used to modify the internal set point for the smoke comparator by use of external resistors
to VDD or VSS. Nominal values for the internal resistor divider are indicated on the block diagram. These internal
resistor values can vary by up to ±20% but the resistor matching should be <2% on any one device. Transmission
switches on VSEN and LBADJ prevent any interaction from the external adjustment resistors.
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.
Transmission switches on VSEN and LBADJ prevent any interaction from external adjustment resistance.
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 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 the alarm condition (1.67S).
The interconnect input has a 500mS nominal digital filter. This allows for interconnection to other types of alarms
(carbon monoxide for example) that may have a pulsed interconnect signal.
Testing – At power up all internal registers are reset. The low battery set point can be tested at power up by
holding FEED and OSCAP low at power up. HB will change state as VDD passes through the low battery set
point. 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.
Timer Mode – The transition of pin 1 (TSTART) from a high to low level initiates a ten minute timer. During this 10
minute period the open drain NMOS on pin 4 (TSTROBE) is strobed on with the internal clock. A resistor
connected to this pin could be used to modify the detector sensitivity for the timer period.
© 2009 Microchip Technology Inc.
DS22173A-page 5
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Typical Application
Figure 2
Notes:
Select R9 to reduce sensitivity during the timer mode.
R3, R4 and C1 are typical values and may be adjusted to maximize sound pressure.
C2 should be located as close as possible to the device power pins.
Route the pin 8 PC board trace away from pin 7 to avoid coupling.
© 2009 Microchip Technology Inc.
DS22173A-page 6
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Typical Single Button Application
Figure 3
Notes:
Select R5 and R6 for the correct level to test the ion chamber. The voltage level on pin 1 (TSTART) must be
greater than the VIH level to initiate the timer. Pin 1 has an internal 180K nominal pull down which must be
considered.
Select R9 to reduce sensitivity during the timer mode.
R3, R4 and C1 are typical values and may be adjusted to maximize sound pressure.
C2 should be located as close as possible to the
Route the pin 8 PC board trace away from pin 7 to
device power pins.
avoid coupling.
© 2009 Microchip Technology Inc.
DS22173A-page 7
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Timing Diagram (non Timer Mode)
Standby Mode; No Low Battery; No Alarm
Alarm; No Low Battery
No Alarm; Low Battery
Alarm; Low Battery
Oscillator
Pin 15 > Pin 13
1.67S
Pin 13 > Pin 15; 130mV Level Shift on Pin 13
Pin 15 > Pin 13
10.5mS
Internal Clock
24 Clock Cycles (40 S)
24 Clock Cycles (1S)
LED
Sample Smoke
Low Battery Warning Chirp
Horn
See Figure Below for Complete Horn Cycle
TIODLY1
IO (Pin 2) as Output
Timing not same scale as above
IO Charge Dump
TIOFILT
IO ( Pin 2) as Input
LED supressed in remote alarm mode
TIODLY2
Horn
Start of horn temporal pattern is not synchronized to an external alarm
Horn pattern not self completing for external alarm,see timing below for complete horn cycle
Internal Clock
Notes:
1. Smoke is not sampled when the horn is active. Horn cycle is self completing in local alarm.
2. Low battery warning chirp is suppressed in local or remote alarm
3. IO Dump active only in local alarm, inactive if external alarm
THON1
THOF1
THOF2
Complete Temporal Horn Pattern
© 2009 Microchip Technology Inc.
DS22173A-page 8
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Timing Diagram (Timer Mode)
Oscillator
10.5mS
1.67S
Internal Clock
TSTART
TLOF3
LED
Outputs High Z
TSTROBE
TTPER
© 2009 Microchip Technology Inc.
DS22173A-page 9
RE46C122
CMOS Ionization Smoke Detector ASIC with
Interconnect and Timer Mode
Product Specification
Information contained in this publication regarding device
applications and the like is provided only for your convenience and
may be superseded by updates. It is your responsibility to ensure
that your application meets with your specifications. MICROCHIP
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OTHERWISE,
RELATED
TO
THE
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R&E International
A Subsidiary of Microchip Technology Inc.
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© 2009 Microchip Technology Inc.
DS22173A-page 10