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R&E International
A Subsidiary of Microchip Technology Inc.
RE46C127
CMOS Ionization Smoke Detector ASIC with Interconnect and Timer Mode Product Specification
General Description
The RE46C127 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. A 2/3 duty cycle continuous horn pattern is used for the alarm condition. An interconnect pin allows multiple detectors to be connected such that when one units alarms all units will sound. An internal 8 minute timer allows for a separate button to be used for reduced sensitivity mode. Although this device was designed for smoke detection utilizing an ionization chamber it could be used in a variety of security applications. Utilizing low power CMOS technology the RE46C127 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 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 8 Minute Timer for Sensitivity Control Compatible with Allegro A5348
Available in Standard Packaging or RoHS Compliant Pb Free Packaging.
Pin Configuration
TSTART IO LBADJ TSTROBE 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
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.
(c) 2009 Microchip Technology Inc.
DS22174A-page 1
RE46C127
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 = 25C, VDD=9V, OSCAP=.1uF, RBIAS=8.2M, VSS=0V (unless otherwise noted) Test Pin
6 6 6 8 2 1 8 2 1 15 15 8 15 15 8 2 4,5 1 10,11 10,11 4 5 2 2 2 6 13 3
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 TSTART=9V IOH=-16mA, VDD=7.2V IOL=16mA, VDD=7.2V IOL=500ua 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 TA=-10 to 60C, Note 3
Parameter
Supply Voltage Supply Current
Symbol
VDD IDD1 IDD2 VIH1 VIH2 VIH3
Test Conditions
Operating RBIAS=8.2M, OSCAP=.1uF RBIAS=8.2M, OSCAP=.1uF;Vdd=12V
Min
6
Limits Typ Max
12 4 6.5 9
Units
V uA uA V V V
Input Voltage High
6.2 No Local Alarm, IO as an Input 3 4.5
4.5
Input Voltage Low
VIL1 VIL2 VIL3
4.5 No Local Alarm, IO as an Input
2.7 1 2.5 -0.75 -1.50 -50 0.75 1.50 50 150 1
V V V pA pA uA pA pA uA uA uA uA V V V V uA mA mA
Input Leakage Low
ILDET1 ILDET2 ILFD
Input Leakage High
IHDET1 IHDET2 IHFD IIOL2
Output Off Leakage High Input Pull Down Current Output High Voltage Output Low Voltage
IIOHZ IPD1 VOH1 VOL1 VOL2 VOL3
20 6.3
50
80 .9 .5 1
Output Current
IIOL1 IIOH1 IIODMP
25 -4 5 7.2 48.5 7.5 50 65.5
60 -16
Low Battery Voltage Internal Sensitivity Set Voltage
VLB VSET1 VSET2
7.8 51.5
V %VDD %VDD
(c) 2009 Microchip Technology Inc.
DS22174A-page 2
RE46C127
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
Offset Voltage
Symbol
VGOS1 VGOS2 VGOS3
Test Pin
14,15 15,16 14,15 14,15 13,15 14,16 13
Test Conditions
Guard Amplifier Guard Amplifier Smoke Comparator Guard Amplifier, Note 2 Smoke Comparator, Note 2 Guard Amplifier Outputs, Note 2 No Alarm to Alarm Condition
Min
-50 -50 -50 2
.5
Limits Typ Max
50 50 50
VDD-.5 VDD-2
Units
mV mV mV V V k mV
Common Mode Voltage
VCM1 VCM2 ZOUT VHYS
Output Impedance Hysteresis
10 90 130 170
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 = 25C, VDD=9V, OSCAP=.1uF, RBIAS=8.2M, VSS=0V (unless otherwise noted) Test Pin
12 12 5 5 5 5 5 10,11 10,11 10,11 10,11 2 2
2 2
Parameter
Oscillator Period
Symbol
TPER1 TPER2 TPW TLON TLOF1 TLOF2 TLOF3
Test Conditions
No Alarm Condition Alarm Condition Operating Operating Standby, No Alarm Alarm Condition Timer Mode, No Alarm 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 No Alarm
Min
1.34 37.5 9.4 9.4 32 .8 8 141 9.4 71 32 1.34
Limits Typ Max
1.67 41.5 10.5 10.5 40 1 10 166 10.5 83 40 1.67 3 450 2 45.8 12.9 12.9 48 1.2 12 190 12.9 95 48 2.0
Units
S mS mS mS S S S mS mS mS S S S mS S Min
Oscillator Pulse Width LED On Time LED Off Time
Horn On Time
THON1 THON2 THOF1 THOF3 TIODMP TIODLY1 TIOFILT TIODLY2 TTPER
Horn Off Time
IO Charge Dump Duration IO Delay IO Filter Remote Alarm Delay Timer Period
.450 6.2 8
2.2 9.8
4
Note 4 - See the timing diagram for complete horn pattern
(c) 2009 Microchip Technology Inc.
DS22174A-page 3
RE46C127
CMOS Ionization Smoke Detector ASIC with Interconnect and Timer Mode Product Specification R&E International
A Subsidiary of Microchip Technology Inc.
Functional Block Diagram
(c) 2009 Microchip Technology Inc.
DS22174A-page 4
RE46C127
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 4kHZ 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 an 8 minute timer. During this 8 minute nominal 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.
(c) 2009 Microchip Technology Inc.
DS22174A-page 5
RE46C127
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.
(c) 2009 Microchip Technology Inc.
DS22174A-page 6
RE46C127
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 device power pins. Route the pin 8 PC board trace away from pin 7 to avoid coupling.
(c) 2009 Microchip Technology Inc.
DS22174A-page 7
RE46C127
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 M ode; No Low Battery; No Alarm Alarm; No Low Battery Alarm; Low Battery No Alarm; Low Battery
Oscillator
Pin 15 > Pin 13 Pin 13 > Pin 15; 130mV Level Shift on Pin 13 Pin 15 > Pin 13
1.67S
10.5mS
Internal Clock
24 Clock Cycles (40 S) 24 Clock Cycles (1S)
Ouput High Z LED
Sample Smoke
THON1 THOF1 Low Battery Warning Chirp
Horn
TIODLY
IO (Pin 2) as Output IO Charge Dump
TI OFI LT
Timing not same scale as above
IO ( Pin 2) as Input
TI ODLY 2
LED supressed in remote alarm mode
Horn
Start of horn pattern is not synchronized to an external alarm
Horn pattern not self completing for external alarm
Internal Clock Notes: 1. Smoke is not sampled w hen the horn is active. Horn cycle is self completing in local alarm. 2. Low battery w arning chirp is suppressed in local or remote alarm 3. IO Dump active only in local alarm, inactive if external alarm
(c) 2009 Microchip Technology Inc.
DS22174A-page 8
RE46C127
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
(c) 2009 Microchip Technology Inc.
DS22174A-page 9
RE46C127
CMOS Ionization Smoke Detector ASIC with Interconnect and Timer Mode Product Specification
Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, rfPIC, SmartShunt and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, nanoWatt XLP, PICkit, PICDEM, 32 logo, PowerCal, PowerInfo, PICDEM.net, PICtail, PIC PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2009, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper.
R&E International
A Subsidiary of Microchip Technology Inc.
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 MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights.
Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company's quality system processes and procedures are for its PIC(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip's quality system for the design and manufacture of development systems is ISO 9001:2000 certified.
(c) 2009 Microchip Technology Inc.
DS22174A-page 10

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