CHERRY CS235GDW18

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
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DET
REF
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
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