CS235 CS235 System Photoelectric Smoke Detector Features Description The CS235 System Smoke Detector is a photo electric type with a pulsed infrared LED as the light source and a silicon photodiode as the light detector. The CS235 IC, along with passive external components, controls the system timing and signal processing. Low average current is attained by pulsing the system once every 10 seconds for 20 milliseconds. Bias is applied to the signal processing circuitry for this time interval. During the second half of the pulse, the last 10 milliseconds, the IR LED is pulsed and the unit samples for an alarm level smoke condition. After the first alarm level signal the sample rate increases to a two second interval. After three consecutive alarm level samples the logic drives the output latch signalling the system panel. The signal processing circuit blocks are amplifiers A1 and A2, synchronous detector, voltage comparator and the decode counter. The voltage gain of A2 and the comparator reference voltage are set by external resistors. Additional on-chip features include an ICC current limiter. The current limiter eliminates power-on false alarming. The oscillator controls the IR LED excitation frequency and provides drive to the synchronous detector. The synchronous detection method has very high noise rejection performance. The internal latch is capable of sinking 100 milliamps maximum and will clamp the VCC pin to 5 volts when tripped. The latch current is determined by an external resistor typically located in the master panel and is reset by temporary removal of detector power. Block Diagram INT OSC TIMER PGM PULSE LED H.L. VR ICC VCC/ Gnd BIAS PGM CAP RES WIDTH PGM OUT GATE POWER UP CURRENT LIMITER MAIN TIMER LED DRIVER OSCILLATOR ■ Synchronous Detection for High Noise Immunity ■ Pulsed Operation for Low Average Current Drain ■ System Gain Externally Set ■ System Sensitivity Externally Adjustable ■ System Operation Monitored by Means of External Red LED Package Options 18 Lead PDIP & SOIC Wide Timer Pulse Width 1 18 Timer Cap ICC Program 2 17 VCC /Output 3 16 Timer Period Program V REG Hi Level GND 4 15 A1 Input (-) 5 14 LED Output Oscillator Program 13 Internal Bias A1 Input (+) 6 NC LO Level GND 7 12 A2 Input 8 11 Detector Output A2 Output 9 10 Detector Reference OUTPUT LATCH CLOCK GATE BIAS POWER UP BIAS SET A1 IN (-) A1 SYNC DETECTOR A2 A1 IN (+) L.L. A2 GND IN A2 OUT COUNTER COMP NC DET OUT ¥¥ Ð3 DET REF Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: [email protected] Web Site: www.cherry-semi.com Rev. 7/6/98 1 A ¨ Company CS235 Absolute Maximum Ratings Lead Temperature Soldering Wave Solder (through hole styles only) .....................................................................................10 sec. max, 260¡C peak Reflow (SMD styles only) ......................................................................................60 sec. max above 183¡C, 230¡C peak Storage Temperature Range ..................................................................................................................................-65¡C to 150¡C Electrical Characteristics: TA = 25¡C, unless otherwise stated. PARAMETER Absolute Maximum Voltage Output Latch Current Operation Temperature Range, TA TEST CONDITIONS TYP (pin 3) 0 ■ 24V System (C2 = 100 µF, R7 = 12 M½) Operating Voltage (pin 3) Average Supply Current V (pin 3) = 22.5V Peak Supply Current V (pin 3) = 22.5V )(non Òspeed upÓ) Peak Supply Current V (pin 16) = 12V )(Òspeed upÓ) Regulator Voltage (pin 16) ■ 12V System (C2 = 150µF, R7 = 12M½) Operating Voltage (pin 3) Average Supply Current V (pin 3) = 12V Peak Supply Current V (pin 3) = 12V (non Òspeed upÓ) Peak Supply Current V (pin 16) = 8V (Òspeed upÓ mode) Regulator Voltage (pin 16) (V pin 3 = 12V) ■ Oscillator Output Frequency Sink Current Source Current High Trip Point Voltage Low Trip Point Voltage MIN R6 = 18k½, C3 = .0068µF (pin 14) (pin 14) (pin 14) (pin 14) ■ LED Drive (Detector LED and Status LED) Source Current (pin 15) R8=36½ Detector LED V IR LED = 1.156V Status LED (alarm) V Status LED = 1.99V Regulator Voltage (pin 15) ISOURCE = 30mA 13.8 22.5 35 150 12.8 8.7 MAX UNIT 38 100 70 V mA ¡C 35 60 100 350 15.7 V µA µA µA V 60 100 350 V µA µA µA V 12 11.85 2.1 16 19 1.8 1.2 3.3 26 26 1.9 1.4 4.4 35 32 2.2 1.5 kHz µA µA V V 20 10 3.7 30 40 4.4 5.2 mA mA V 1000 1000 250 dB nA nA nA ■ Amplifier A1 Fixed Gain Input Current B1 Input Current B2 Input current (B1-B2) 26 500 500 (pin 5) (pin 6) 2 PARAMETER ■ Amplifier A2 DC Output (pin 9) Input Bias Current (pin 8) Voltage gain @ 3.5kHz TEST CONDITIONS R3 = 6k½, R4 = 510½, C5 = .47µF (Externally adjusted gain with R3 and R4. Unity DC gain) (Externally adjusted gain with R3 and R4. Unity DC gain) ■ Detector and Reference Output (C4 = .47µF) Reference Resistance Reference Voltage (pin 10) Detector Output Resistance Detector Output Voltage (pin 11) (No signal, and at 2X time Constant) ■ Output Circuit Output Latch Voltage Leakage Current TYP MAX UNIT 250 V nA 2.5 21.6 dB 13 1.8 10 1.4 19 3.6 15 2.8 25 5.5 20 4.3 k½ V k½ V 8 1.5 10 2 20 10 12 2.5 Sec Sec ms ms V (pin 16) = 16V V (pin 16) = 16V 415 -220 460 -235 505 -250 nA µA (pin 3) ISUPPLY = 100mA V (pin 3) = 38V, V (pins 2, 16) = 0V 4.4 5.2 500 6.1 V µA ■ Main Timer (R1 = 20M½, R2 = 75k½, C1 = .47µF) Power Up Pulse Period Standby Mode (pin 1) Power Up Pulse Period Speed Up Mode (pin 1) Power Up Pulse Width (pin 1) Gate Pulse Width Power up pulse width 12 Sink Current (pin 18) Source Current (pin 18) MIN ■ Alarm Alarm Reset Supply interruption 5 Sec Power up time 30 Sec System will go into alarm upon detection and transfer of three consecutive alarm level signals into the counter. 3 CS235 Electrical Characteristics: TA = 25¡C CS235 Timing Diagrams Timing Diagram Out of Alarm Timing Diagram In Alarm 10 Sec. 20ms Power Up 20ms 20ms Gate (Clock) 10ms Gate (Clock) 10ms 3.5KHz 3.5KHz Oscillator/ LED Driver Oscillator/ LED Driver Comp. Ref. Comp. Ref. Comp. Ref. Level 2 Sec. Power Up Comp. Ref. Level Detector Output Detector Output Data Input Data Input (low) Alarm Enable Alarm Enable (low) Preset Preset 4 CS235 Application Diagram C3 6.8nF R6 18k 13 14 CS235 LED Driver 15 Gate Oscillator Power UP Main Timer R8 36W R9 270k 1nF C7 R12 150k R11 150k 17 R1 20M C1 .47mF Clock IR LED 1nF C6 R2 75k 18 Status LED PGnd 1 16 C2 150mF 4 5 Current Limit R7 12M + A1 Synchronous Detector + Gain =20 6 2 - COMP A2 Counter Ð¥¥ 3 Output Latch - R12 R13 150k 150k 8 11 10 9 7 LLGnd R3 6k R5 100K R4 510W C4 .47mF C5 .47mF 5 3 VCC/Output CS235 Package Specification PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA D Lead Count 18L PDIP 18L SO Wide Metric Max Min 23.37 22.35 11.75 11.35 Thermal Data English Max Min .920 .880 .463 .447 RQJC RQJA typ typ 18L SO Wide 21 100 18L PDIP 29 65 ûC/W ûC/W Plastic DIP (N); 300 mil wide 7.11 (.280) 6.10 (.240) 1.77 (.070) 1.14 (.045) 8.26 (.325) 7.62 (.300) 2.54 (.100) BSC 3.68 (.145) 2.92 (.115) .356 (.014) .203 (.008) 0.39 (.015) MIN. .558 (.022) .356 (.014) REF: JEDEC MS-001 D Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. Surface Mount Wide Body (DW); 300 mil wide 7.60 (.299) 7.40 (.291) 10.65 (.419) 10.00 (.394) 0.51 (.020) 0.33 (.013) 1.27 (.050) BSC 2.49 (.098) 2.24 (.088) 1.27 (.050) 0.40 (.016) 2.65 (.104) 2.35 (.093) 0.32 (.013) 0.23 (.009) D REF: JEDEC MS-013 0.30 (.012) 0.10 (.004) Ordering Information Part Number CS235GDW18 CS235GDWR18 CS235GN18 Rev. 7/6/98 Description 18L SO 18L SO (tape & reel) 18L PDIP Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. 6 © 1999 Cherry Semiconductor Corporation