CS235

CS235 CHERRY | Alldatasheet

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Technical content

Features

Ð3¥¥ CLOCK POWER UP BIAS COMPSYNC DETECTORA2A1 DET REF DET OUT NCA2 OUT IN L.L. GND A1 IN (+) A1 IN (-) INT BIAS OSC PGM TIMER CAP PGM RES PULSE WIDTH LED H.L. Gnd VR ICC PGM VCC/ OUT n Synchronous Detection for High Noise Immunity n Pulsed Operation for Low Average Current Drain n System Gain Externally Set n System Sensitivity Externally Adjustable n System Operation Monitored by Means of External Red LED Package Options CS235 System Photoelectric Smoke Detector CS235

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 compo- nents, 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 cir- cuitry 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 sam- ple rate increases to a two second interval. After three consecutive alarm level samples the logic drives the output latch signalling the sys- tem panel. The signal processing circuit blocks are amplifiers A1 and A2, syn- chronous detector, voltage com- parator 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 I CC 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 perfor- mance. The internal latch is capable of sink- ing 100 milliamps maximum and will clamp the V CC 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 Timer Pulse Width ICC Program VCC /Output Hi Level GND A1 Input (-) A1 Input (+) LO Level GND A2 Input Timer Cap Timer Period Program V REG LED Output Oscillator Program Internal Bias NC Detector Output 9A2 Output Detector Reference

18 Lead PDIP & SOIC Wide

1 A Company ¨

Rev. 7/6/98 Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi.com Web Site: www.cherry-semi.com

Electrical Characteristics: TA = 25¡C, unless otherwise stated. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT CS235 Absolute Maximum Ratings Lead Temperature Soldering Absolute Maximum Voltage (pin 3) 38 V Output Latch Current 100 mA Operation Temperature 0 70 ¡C Range, TA n 24V System (C2 = 100 µF, R7 = 12 M½) Operating Voltage (pin 3) 13.8 22.5 35 V Average Supply Current V (pin 3) = 22.5V 35 60 µA Peak Supply Current V (pin 3) = 22.5V )(non Òspeed upÓ) 100 µA Peak Supply Current V (pin 16) = 12V )(Òspeed upÓ) 150 350 µA Regulator Voltage (pin 16) 12.8 15.7 V n 12V System (C2 = 150µF, R7 = 12M½) Operating Voltage (pin 3) 8.7 12 V Average Supply Current V (pin 3) = 12V 60 µA Peak Supply Current V (pin 3) = 12V (non Òspeed upÓ) 100 µA Peak Supply Current V (pin 16) = 8V (Òspeed upÓ mode) 350 µA Regulator Voltage (pin 16) (V pin 3 = 12V) 11.85 V n Oscillator Output Frequency R6 = 18k½, C3 = .0068µF 2.1 3.3 4.4 kHz Sink Current (pin 14) 16 26 35 µA Source Current (pin 14) 19 26 32 µA High Trip Point Voltage (pin 14) 1.8 1.9 2.2 V Low Trip Point Voltage (pin 14) 1.2 1.4 1.5 V n LED Drive (Detector LED and Status LED) Source Current (pin 15) R8=36½ Detector LED V IR LED = 1.156V 20 30 40 mA Status LED (alarm) V Status LED = 1.99V 10 mA Regulator Voltage (pin 15) I SOURCE = 30mA 3.7 4.4 5.2 V n Amplifier A1 Fixed Gain 26 dB Input Current B1 (pin 5) 500 1000 nA Input Current B2 (pin 6) 500 1000 nA Input current (B1-B2) 250 nA

Electrical Characteristics: TA = 25¡C PARAMETER TEST CONDITIONS MIN TYP MAX UNIT n Amplifier A2 DC Output (pin 9) R3 = 6k½, R4 = 510½, C5 = .47µF 2.5 V Input Bias Current (pin 8) (Externally adjusted gain 250 nA with R3 and R4. Unity DC gain) Voltage gain @ 3.5kHz (Externally adjusted gain 21.6 dB with R3 and R4. Unity DC gain) n Detector and Reference Output (C4 = .47µF) Reference Resistance 13 19 25 k½ Reference Voltage (pin 10) 1.8 3.6 5.5 V Detector Output Resistance 10 15 20 k½ Detector Output Voltage (pin 11) 1.4 2.8 4.3 V (No signal, and at 2X time Constant) n Main Timer (R1 = 20M½, R2 = 75k½, C1 = .47µF) Power Up Pulse Period Standby Mode (pin 1) 8 10 12 Sec Power Up Pulse Period Speed Up Mode (pin 1) 1.5 2 2.5 Sec Power Up Pulse Width (pin 1) 20 ms Gate Pulse Width Power up pulse width 12 10 ms Sink Current (pin 18) V (pin 16) = 16V 415 460 505 nA Source Current (pin 18) V (pin 16) = 16V -220 -235 -250 µA n Output Circuit Output Latch Voltage (pin 3) I SUPPLY = 100mA 4.4 5.2 6.1 V Leakage Current V (pin 3) = 38V, V (pins 2, 16) = 0V 500 µA n 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.

Gate (Clock) 10ms 3.5KHz Oscillator/ LED Driver Comp. Ref. Comp. Ref. Level Detector Output Data Input (low) Alarm Enable (low) Preset 10 Sec. 20ms 2 Sec. Power Up20ms Gate (Clock) 10ms 3.5KHz Oscillator/ LED Driver Comp. Ref. Comp. Ref. Level Detector Output Data Input Alarm Enable Preset Timing Diagram In AlarmTiming Diagram Out of Alarm Timing Diagrams CS235

.47mF 100K SynchronousDetector Output Latch Clock OscillatorLED Driver 36W Status LED IR LED Power UP Main Timer Current Limit 18k 6.8nF Gate .47mF 270k 1nF R11 150k Gain =20 ¥ VCC/OutputCOMP CS235 PGnd 1nF 75k 20M .47mF 150mF LLGnd 12M CounterÐ 3¥6 13 14 9 11 108 7 R12 150k R12 150k R13 150k

RQJC typ 21 29 ûC/W RQJA typ 100 65 ûC/W 6Rev. 7/6/98 Package Specification PACKAGE DIMENSIONS IN mm (INCHES) D Lead Count Metric English Max Min Max Min 18L PDIP 23.37 22.35 .920 .880 18L SO Wide 11.75 11.35 .463 .447 PACKAGE THERMAL DATA CS235

Ordering Information

CS235GDWR18 18L SO (tape & reel) CS235GN18 18L PDIP © 1999 Cherry Semiconductor Corporation Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. Plastic DIP (N); 300 mil wide 0.39 (.015) MIN. 1.14 (.045) D Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. .203 (.008) .356 (.014) REF: JEDEC MS-001 3.68 (.145) 2.92 (.115) 8.26 (.325) 7.62 (.300) 7.11 (.280) 6.10 (.240) .356 (.014) .558 (.022) Surface Mount Wide Body (DW); 300 mil wide 1.27 (.050) BSC 7.60 (.299) 7.40 (.291) 10.65 (.419) 10.00 (.394) D 0.32 (.013) 0.23 (.009) 1.27 (.050) 0.40 (.016) REF: JEDEC MS-013 2.49 (.098) 2.24 (.088) 0.51 (.020) 0.33 (.013) 2.65 (.104) 2.35 (.093) 0.30 (.012) 0.10 (.004)