R&E International A Subsidiary of Microchip Technology Inc. RE46C127 CMOS Ionization Smoke Detector ASIC with Interconnect and Timer Mode Product Specification General Description Features 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. 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 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. 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 TSTROBE Utilizing low power CMOS technology the RE46C127 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. 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 = 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 4 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 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 Limits Typ Max Symbol Test Pin VGOS1 14,15 Guard Amplifier -50 50 mV VGOS2 15,16 Guard Amplifier -50 50 mV VGOS3 14,15 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 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) Parameter Symbol Test Pin TPER1 12 Oscillator Period Min Limits Typ Max No Alarm Condition 1.34 1.67 2 S Alarm Condition 37.5 41.5 45.8 mS Test Conditions Units TPER2 12 Oscillator Pulse Width TPW 5 Operating 9.4 10.5 12.9 mS LED On Time TLON 5 Operating 9.4 10.5 12.9 mS LED Off Time 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 141 166 190 mS THON2 10,11 Low Battery, No Alarm 9.4 10.5 12.9 mS THOF1 10,11 Operating, Alarm Condition 71 83 95 mS Low Battery, No Alarm 32 40 48 S 1.34 1.67 2.0 S Horn On Time Horn Off Time THOF3 10,11 IO Charge Dump Duration TIODMP 2 At Conclusion of Local Alarm or Test IO Delay TIODLY1 2 From Start of Local Alarm to IO Active IO Filter Remote Alarm Delay Timer Period TIOFILT 2 TIODLY2 2 TTPER 4 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 .450 6.2 8 S 450 mS 2.2 S 9.8 Min Note 4 – See the timing diagram for complete horn pattern © 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 © 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. © 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. © 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. © 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 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) Ouput High Z LED Sample Smoke THON1 THOF1 Low Battery Warning Chirp Horn TIODLY IO (Pin 2) as Output Timing not same scale as above IO Charge Dump TI OFI LT IO ( Pin 2) as Input LED supressed in remote alarm mode TI ODLY 2 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 © 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 © 2009 Microchip Technology Inc. DS22174A-page 9 RE46C127 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. 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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. © 2009, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. 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® MCUs and dsPIC® DSCs, KEELOQ® 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. © 2009 Microchip Technology Inc. DS22174A-page 10