R&E International A Subsidiary of Microchip Technology Inc. RE46C120 CMOS Ionization Smoke Detector ASIC Product Specification General Description Features The RE46C120 is a low power CMOS ionization type smoke detector IC. With a 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 TONE input allows for selection of a temporal pattern or a 2/3 duty cycle continuous tone. The temporal horn pattern supports the NFPA 72 emergency evacuation signal. Although this device was designed for smoke detection utilizing an ionization chamber it could be used in a variety of security applications. Guard Outputs for Ion Detector Input +/-0.75pA Detect Input Current Internal Reverse Battery Protection Internal Low Battery Detection Pin Selectable Horn Pattern Low Quiescent Current Consumption (<6.5uA) 16L PDIP ESD Protection on all Pins Compatible with MC145017, MC14467 Available in RoHS Compliant Pb Free Packaging Pin Configuration DETCOMP 1 16 GUARD2 N/C 2 15 DETECT LBADJ 3 14 GUARD1 TONE 4 13 VSEN LED 5 12 OSCAP VDD 6 11 HS RBIAS 7 10 HB FEED 8 9 Utilizing low power CMOS technology the RE46C120 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 FEED Input Voltage Range Reverse Battery Time Input Current except FEED Operating Temperature Storage Temperature Maximum Junction Temperature SYMBOL VDD Vin Vinfd TRB Iin TA TSTG TJ VALUE 15 -.3 to Vdd +.3 -10 to +22 5 10 -10 to 60 -55 to 125 150 UNITS 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. DS22157A-page 1 RE46C120 CMOS Ionization Smoke Detector ASIC Product Specification R&E International A Subsidiary of Microchip Technology Inc. DC Electrical Characteristics at TA = 25°C, VDD=9V, VSS=0V (unless otherwise noted) Symbol Test Pin Supply Voltage VDD 6 Operating Supply Current IDD1 6 RBIAS=8.2MΩ, OSCAP=.1uF RBIAS=8.2MΩ, OSCAP=.1uF;Vdd=12V Parameter IDD2 6 Input Voltage High VIH 4,8 Input Voltage Low VIL 4,8 Input Leakage Low ILDET1 Input Leakage High Test Conditions Min Limits Typ Max 6 4.5 6.2 12 V 6.5 uA 9 uA 4.5 4.5 Units V 2.7 V 15 VDD=9V, DETECT=VSS, 0-40% RH -0.75 pA ILDET2 15 VDD=9V, DETECT=VSS, 85% RH Note 1 -1.50 pA ILTONE 4 TONE=VSS, RBIAS=8.2MΩ, -450 nA ILFD 8 FEED=-10V -50 uA IHDET1 15 VDD=9V, DETECT=VDD, 0-40% RH 0.75 pA IHDET2 15 VDD=9V, DETECT=VDD, 85% RH Note 1 1.50 pA 50 uA 1 uA -100 IHFD 8 FEED=22V Output Off Leakage High IOHZ 5 LED Off Output Voltage High VOH1 10,11 VOH2 1 VOL1 10,11 IOL=16mA, VDD=7.2V .9 V VOL2 1 IOL=30ua .5 V VOL3 5 IOL=10mA, VDD=7.2V 3 V VLB 6 TA=-10 to 60ºC, Note 3 VSET1 13 VSET2 3 VGOS1 VGOS2 Output Voltage Low Low Battery Voltage Internal Sensitivity Set Voltage Offset Voltage Common Mode Voltage IOH=-16mA, VDD=7.2V 6.3 V IOH=-30ua 8.5 V 7.2 7.5 7.8 V 47 50 53 %VDD 65.5 %VDD 14,15 Guard Amplifier -50 50 mV 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 170 mV 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 10 90 130 kΩ 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. DS22157A-page 2 RE46C120 CMOS Ionization Smoke Detector ASIC 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) Min Limits Typ Max No Alarm Condition 1.34 1.67 2 S Alarm Condition 37.5 41.5 45.8 mS Operating 9.1 10.5 12.9 mS 5 Operating 9.1 10.5 12.9 mS TLOF1 5 Standby, No Alarm 32 40 48 S TLOF2 5 Alarm Condition Symbol Test Pin TPER1 12 TPER2 12 Oscillator Pulse Width TPW 5 LED On Time TLON LED Off Time Parameter Oscillator Period Horn On Time Horn Off Time Test Conditions Units .9 1 1.1 S 450 500 550 mS THON1 10,11 Operating, Alarm Condition, Note 4, TONE=VDD or Float THON2 10,11 Low Battery, No Alarm 9.1 10.5 12.9 mS THON3 10,11 Operating, Alarm Condition, TONE=Low 150 166 183 mS 450 500 550 mS 1.35 1.5 1.65 S THOF1 10,11 THOF2 10,11 Operating, Alarm Condition, Note 4, TONE=VDD or Float Operating, Alarm Condition, Note 4, TONE=VDD or Float THOF3 10,11 Operating, Alarm Condition, TONE=Low 75 83 92 mS THOF4 10,11 Low Battery, No Alarm 32 40 48 S Note 4: See timing diagram for Horn Temporal Pattern Functional Block Diagram Figure 1 © 2009 Microchip Technology Inc. DS22157A-page 3 RE46C120 CMOS Ionization Smoke Detector ASIC Product Specification R&E International A Subsidiary of Microchip Technology Inc. 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 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 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 typically 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 Zener 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 10mS 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. Testing – At power up all internal registers are reset. 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 should be maintained for proper operation of the analog circuitry. Please refer to the timing diagrams. Horn Tone – Pin 4 selects the NFPA72 horn tone (high or floating) or the 2/3 duty cycle continuous tone (low). If this pin is externally connected high, use a current limiting resistor from pin 4 to VDD. Reverse Battery Protection – The RE46c120 internally limits the current from VSS to VDD in the event of accidental polarity reversal. If an input is connected to VDD it should be done through a resistance of at least 1.5K to limit the reverse current through this path. © 2009 Microchip Technology Inc. DS22157A-page 4 RE46C120 CMOS Ionization Smoke Detector ASIC Product Specification R&E International A Subsidiary of Microchip Technology Inc. Typical Application Figure 2 Notes: 1. Float or connect pin 4 to VDD through 1.5kOhm minimum for NFPA72 temporal horn pattern, connect to VSS for 2/3 duty cycle continuous tone. 2. R3, R4 and C1 are typical values and may be adjusted to maximize sound pressure. 3. C2 should be located as close as possible to the device power pins. 4. Route the pin 8 PC board trace away from pin 7 to avoid coupling. © 2009 Microchip Technology Inc. DS22157A-page 5 RE46C120 CMOS Ionization Smoke Detector ASIC Product Specification R&E International A Subsidiary of Microchip Technology Inc. Timing Diagram Standby Mode; 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 10mS Internal Clock 24 Clock Cycles (40 S) 24 Clock Cycles (1S) LED DETCOMP (pin1) Sample (2/3 Duty) Sample (NFPA72) THON3 THOF3 Low Battery Warning Chirp Horn (2/3 Duty Cycle, TONE=VSS) Low Battery Warning Chirp Horn (NFPA72, TONE=Open) See Figure Below for Complete Temporal Horn Cycle Notes: 1. Smoke is not sampled when the horn is active so the horn cycle is self completing 2. Low battery warning chirp is suppressed in alarm THON1 THOF1 THOF2 Complete Temporal Horn Pattern © 2009 Microchip Technology Inc. DS22157A-page 6 RE46C120 CMOS Ionization Smoke Detector ASIC 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. 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