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PDF RE46C121 Data sheet ( Hoja de datos )
| Número de pieza | RE46C121 | |
| Descripción | CMOS Ionization Smoke Detector ASIC | |
| Fabricantes | R & E International | |
| Logotipo |  |
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R&E International
RE46C121
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
General Description
The RE46C121 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 unit alarms all units will
sound.
Although this device was designed for smoke detection
utilizing an ionization chamber it can be used in a
variety of security applications.
Utilizing low power CMOS technology the RE46C121
was designed for use in smoke detectors that comply
with Underwriters Laboratory Specification UL217 and
UL268.
Features
• Guard Outputs for Ion Detector Input
• +/-0.75pA Detect Input Current
• Internal Reverse Battery Protection
• Internal Low Battery Detection
• Low Quiescent Current Consumption (<6.5uA)
• Available in 16L PDIP or 16L N SOIC
• ESD Protection on all Pins
• Interconnect up to 40 Detectors
• Compatible with MC145018
• Available in Standard Packaging or RoHS
Complaint Pb Free Packaging
Pin Configuration
DETCOMP
IO
LBADJ
STROBE
LED
VDD
RBIAS
FEED
1
2
3
4
5
6
7
8
16 GUARD2
15 DETECT
14 GUARD1
13 VSEN
12 OSCAP
11 HS
10 HB
9 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
VDD
Vin
Vinfd
Vio1
TRB
Iin
TA
TSTG
TJ
VALUE
15
-.3 to Vdd +.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
Telephone 610.992.0727
Facsimile 610.992.0734
E-mail: [email protected]
Page 1 of 8
DS-RE46C121-010907
This datasheet contains PROPRIETARY and CONFIDENTIAL information.
1 page  
RE46C121
CMOS Ionization Smoke Detector ASIC with Interconnect
Product Specification
R&E International
DEVICE DESCRIPTION and APPLICATION NOTES
Note: All timing references are nominal values. Refer to the electrical specifications for limits
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).
Pin 13 (VSEN) can be used to modify the internal set point for the smoke comparator by using 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 will be <2% on
any one device. A transmission switch on pin 13 isolates this pin during the low battery test so that the
low battery set point will not be affected if external resistors are used to modify the smoke sensitivity set
point.
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 11mS LED pulse. Pin 3 (LBADJ) can be used to modify the low battery set point by placing a
resistor to VDD or VSS. Note that the internal resistor string is common to both pin 3 and pin 13 so there
will be some interaction between the two. Modification of the low battery set point may affect the smoke
sensitivity setting.
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. For a remote alarm condition the LED is always off.
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
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 - By holding pin 12 (OSCAP) low the internal power strobe is active and pin1 (DETCOMP) can be
used to check for smoke. Please refer to the timing diagrams.
Telephone 610.992.0727
Facsimile 610.992.0734
E-mail: [email protected]
Page 5 of 8
DS-RE46C121-010907
This datasheet contains PROPRIETARY and CONFIDENTIAL information.
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet RE46C121.PDF ] | |
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