Low-Power CMOS Ionization Smoke Detector IC

www.DataSheet4U.com Freescale Semiconductor Technical Data MC14467-1 Rev 5.0, 3/2007 Low-Power CMOS Ionization Smoke Detector IC The MC14467-1, when used with an ionization chamber and a small number of external components, will detect smoke. When smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. Features • • • • • • • • • • Ionization Type with On-Chip FET Input Comparator Piezoelectric Horn Driver Guard Outputs on Both Sides of Detect Input Input-Production Diodes on the Detect Input Low-Battery Trip Point, Internally Set, can be Altered Via External Resistor Detect Threshold, Internally Set, can be Altered Via External Resistor Pulse Testing for Low Battery Uses LED for Battery Loading Comparator Outputs for Detect and Low Battery Internal Reverse Battery Protection Pb-Free Packaging Designated by Suffix Code ED and EG MC14467-1 LOW-POWER CMOS IONIZATION SMOKE DETECTOR IC P SUFFIX ED SUFFIX (PB-FREE) 16-LEAD PLASTIC DIP CASE 648-08 EG SUFFIX (PB-FREE) 16-LEAD SOICW CASE 751G-04 ORDERING INFORMATION Device MC14467P1 648-08 MC14467ED1 MCZ14467EG/R2 751G-04 SOICW Plastic Dip Case No. Package DETECT COMP. OUT N/C LOW V SET LOW V COMP. OUT LED VDD TIMING RESISTOR FEEDBACK 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 GUARD HI-Z DETECT INPUT GUARD LO-Z SENSITIVITY SET OSC CAPACITOR SILVER BRASS VSS DETECT COMP. OUT N/C LOW V SET LOW V COMP. OUT LED VDD TIMING RESISTOR FEEDBACK 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 GUARD HI-Z DETECT INPUT GUARD LO-Z SENSITIVITY SET OSC CAPACITOR SILVER BRASS VSS Figure 1. Pin Connections © Freescale Semiconductor, Inc., 2007. All rights reserved. VDD Priezoelectric Horn Driver 8 4 – + Low Battery Comp. Latch 10 VDD 11 80 K 3 1045 K VDD 7 Oscillator Timer 12 VDD 5 13 + – 15 6 9 Led Driver Latch 1 Detect Input VDD 1125 K 14 + – Lo-Z Active Guard Figure 2. Block Diagram Table 1. Maximum Ratings(1) (Voltages referenced to VSS) Rating DC Supply Voltage Input Voltage, All Inputs Except Pin 8 DC Current Drain per Input Pin, Except Pin 15 = 1 mA DC Current Drain per Output Pin Operating Temperature Range Storage Temperature Range Reverse Battery Time Symbol VDD VIN I I TA TSTG tRB Value −0.5 to + 15 −0.25 to VDD + 0.25 10 30 −10 to +60 −55 to + 125 5.0 Unit V V mA mA °C °C s 1. Maximum Ratings are those values beyond which damage to the device may occur. This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it is recommended that except for pin 8, VIN and VOUT be constrained to the range VSS ≤ (VIN or VOUT ) VDD. For pin 8, refer to the Electrical Characteristics. MC14467-1 2 Sensors Freescale Semiconductor Table 2. Recommended Operating Conditions (Voltages referenced to VSS) Parameter Supply Voltage Timing Capacitor Timing Resistor Battery Load (Resistor or LED) Symbol VDD — — — Value 9.0 0.1 8.2 10 Unit V µF MΩ mA Table 3. Electrical Characteristics (Voltages referenced to VSS, TA = 25°C) Characteristic Operating Voltage Output Voltage Piezoelectric Horn Drivers (IOH = -16 mA) Comparators (IOH = -30 µA) Piezoelectric Horn Drivers (IOL = +16 mA) Comparators (IOL = +30 µA) Output Voltage - LED Driver, IOL = 10 mA Output Impedance, Active Guard Pin 14 Pin 16 Operating Current (Rbias = 8.2 MΩ) Input Current - Detect (40% R.H.) Internal Set Voltage Low Battery Sensitivity Hysteresis Offset Voltage (measured at Vin = VDD/2 Active Guard Detect Comparator Input Voltage Range, Pin 8 Input Capacitance Common Mode Voltage Range, Pin 15 Symbol VDD VOH 7.2 9.0 7.2 9.0 7.2 9.0 9.0 9.0 12.0 9.0 9.0 — 9.0 9.0 9.0 VIN CIN VCM — — — 6.3 8.5 — — — — — — — — 7.2 47 75 — — VSS - 10 — 0.6 — 8.8 — 0.1 — — — 5.0 — — — 50 100 — — — 5.0 — — — 0.9 0.5 3.0 10 1000 9.0 12.0 ± 1.0 7.8 53 150 ± 100 ± 50 VDD + 10 — VDD - 2 V pF V µA pA V %VDD mV mV VDD VDC — Min 6.0 Typ(1) — Max 12 Unit V V VOL VOL LO-Z HI-Z IDD IIN VLOW VSET VHYS VOS V V kΩ 1. Data labelled “Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. MC14467-1 Sensors Freescale Semiconductor 3 Table 4. Timing Parameters (C = 0.1 µF, Rbias = 8.2 MΩ, VDD = 9.0 V, TA = 25°C, See Figure 7) Characteristics Oscillator Period Oscillator Rise Time Horn Output (During Smoke) LED Output Horn Output (During Low Battery) On Time Off Time Between Pulses On Time On Time Between Pulses No Smoke Smoke Symbol tCI tR PWON PWOFF tLED PWON tON tOFF Min 1.34 32 8.0 120 60 32 8.0 8.0 32 Typ(1) 1.67 40 10 160 80 40 10 10 40 Max 2.0 48 12 208 104 48 12 12 48 Units s ms ms ms ms s ms ms s 1. Data labelled “Typ” is not to be used for design purposes but is intended as an indication of the IC’s potential performance. 100.0 VDD = 9.0 VDC 10.0 ID , Drain Current (mA) VDD = 7.2 VDC TA = 25°C 10.0 TA = 25°C 1.0 ID , Drain Current (mA) 1.0 VDD = 9.0 VDC or 7.2 VDC 0.1 P-CH Source And N-CH Sink Current 0.1 0 1 2 3 4 5 6 7 8 9 10 0.01 0 1 2 3 4 5 6 7 8 9 10 VDS, Drain To Source Voltage (VDC) VDS, Drain To Source Voltage (VDC) Figure 3. Typical LED Output I-V Characteristic 1000.0 TA = 25°C ID, Drain Current (mA) 100.0 VDD = 9.0 VDC Figure 4. Typical Comparator Output I-V Characteristic 1000.0 TA = 25°C 100.0 ID, Drain Current (mA) VDD = 9.0 VDC 10.0 VDD = 7.2 VDC 10.0 VDD = 7.2 VDC P-CH Source Current 1.0 0 1 2 3 4 5 6 7 8 9 10 1.0 0 1 2 3 4 N-CH Sink Current 5 6 7 8 9 10 VDS, Drain To Source Voltage (VDC) VDS, Drain To Source Voltage (VDC) Figure 5. Typical P Horn Driver Output I-V Characteristic MC14467-1 4 Sensors Freescale Semiconductor DEVICE OPERATION Timing The internal oscillator of the MC14467-1 operates with a period of 1.67 seconds during no-smoke conditions. Each 1.67 seconds, internal power is applied to the entire IC and a check is made for smoke, except during LED pulse, Low Battery Alarm Chirp, or Horn Modulation (in smoke). Every 24 clock cycles a check is made for low battery by comparing VDD to an internal zener voltage. Since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. Detect Circuitry If smoke is detected, the oscillator period becomes 40 ms and the piezoelectric horn oscillator circuit is enabled. The horn output is modulated 160 ms on, 80 ms off. During the off time, smoke is again checked and will inhibit further horn output if no smoke is sensed. During smoke conditions the low battery alarm is inhibited, but the LED pulses at a 1.0 Hz rate. An active guard is provided on both pins adjacent to the detect input. The voltage at these pins will be within 100 mV of the input signal. This will keep surface leakage currents to a minimum and provide a method of measuring the input voltage without loading the ionization chamber. The active guard op amp is not power strobed and thus gives constant protection from surface leakage currents. Pin 15 (the Detect input) has internal diode protection against static damage. Sensitivity/Low Battery Thresholds Both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see Figure 2) connected between VDD and VSS. These voltages can be altered by external resistors connected from pins 3 or 13 to either VDD or VSS. There will be a slight interaction here due to the common voltage divider network. The sensitivity threshold can also be set by adjusting the smoke chamber ionization source. Test Mode Since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or time-consuming. By forcing Pin 12 to VSS, the power strobing is bypassed and the outputs, Pins 1 and 4, constantly show smoke/no smoke and good battery/low battery, respectively. Pin 1 = VDD for smoke and Pin 4 = VDD for low battery. In this mode and during the 10 ms power strobe, chip current rises to approximately 50 µA. LED Pulse The 9-volt battery level is checked every 40 seconds during the LED pulse. The battery is loaded via a 10 mA pulse for 10 ms. If the LED is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 mA. Hysteresis When smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. This yields approximately 100 mV of hysteresis and reduces false triggering. 1M 1M Test 1 2 3 4 330 Ω 5 6 7 8.2 MΩ 0.1 µF + 9.0 V 8 MC14467-1 16 15 14 13 12 11 10 9 0.1 µF 1.5 MΩ* 0.001* µF 220 kΩ* *NOTE: Component values may change depending on type of piezoelectric horn used. Figure 6. Typical Application as Ionization Smoke Detector MC14467-1 Sensors Freescale Semiconductor 5 Standby No Smoke/ No Low Battery Smoke/no Low Battery OSCILLATOR (Pin 12) DETECT OUT (Pin 1) LOW BATTERY OUT (Pin 4) HYSTERESIS (Internal) (Pins 13 & 14) SAMPLE (Internal) Smoke HORN (Pins 10 & 11) Battery Test LED (Pin 5) 24 Clock Cycles (40 s) 24 Clock Cycles (0.96 s) Smoke/Low Battery 40 m s 10 m s No Smoke/low Battery 1.67 s (Note 1) Suppressed Chirp (Note 3) 24 Clock Cycles (Note 3) 6 Clock Cycles (10.0 s) Notes: 1. Horn modulation is self-completing. When going from smoke to no smoke, the alarm condition will terminate only when horn is off. 2. Comparators are strobed on once per clock cycle (1.67 s for no smoke, 40 ms for smoke). 3. Low battery comparator information is latched only during LED pulse. 4. ~ 100 mVp–p swing. Figure 7. Timing Diagram MC14467-1 6 Sensors Freescale Semiconductor PACKAGE DIMENSIONS CASE 648-08 ISSUE T 16-