RE46C190
CMOS Low Voltage Photoelectric Smoke Detector ASIC
with Interconnect and Timer Mode
Features
•
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•
•
•
•
•
•
•
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Two AA Battery Operation
Internal Power On Reset
Low Quiescent Current Consumption
Available in 16L N SOIC
Local Alarm Memory
Interconnect up to 40 Detectors
9 Minute Timer for Sensitivity Control
Temporal or Continuous Horn Pattern
Internal Low Battery and Chamber Test
All Internal Oscillator
Internal Infrared Emitter Diode (IRED) driver
Adjustable IRED Drive current
Adjustable Hush Sensitivity
2% Low Battery Set Point
Description
The RE46C190 is a low power, low voltage CMOS
photoelectric type smoke detector IC. With minimal
external components, this circuit will provide all the
required features for a photoelectric-type smoke
detector.
The design incorporates a gain-selectable photo
amplifier for use with an infrared emitter/detector pair.
An internal oscillator strobes power to the smoke
detection circuitry every 10 seconds, to keep the
standby current to a minimum. If smoke is sensed, the
detection rate is increased to verify an Alarm condition.
A high gain mode is available for push button chamber
testing.
A check for a low battery condition is performed every
86 seconds, and chamber integrity is tested once every
43 seconds, when in Standby. The temporal horn pat-
tern supports the NFPA 72 emergency evacuation sig-
nal.
An interconnect pin allows multiple detectors to be
connected such that, when one unit alarms, all units will
sound.
An internal 9 minute timer can be used for a Reduced
Sensitivity mode.
Utilizing low power CMOS technology, the RE46C190
was designed for use in smoke detectors that comply
with Underwriters Laboratory Specification UL217 and
UL268.
PIN CONFIGURATION
RE46C190
SOIC
V
SS
IRED
V
DD
TEST
TEST2
IRP
IRN
RLED
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
LX
V
BST
HS
HB
IO
IRCAP
FEED
GLED
2010 Microchip Technology Inc.
DS22271A-page 1
RE46C190
TYPICAL BLOCK DIAGRAM
TEST2 (5)
TEST (4)
Precision
Reference
V
DD
(3)
R3
R4
+
-
IRP (6)
IRN (7)
Photo
Integrator
+
-
Low Battery
Comparator
LX (16)
Boost Control
Current
Sense
Boost Comparator
Smoke
Comparator
Control
Logic and
Timing
Level
Shift
Horn Driver
+
-
IRCAP (11)
Programmable
Limits
High
Normal
Hysteresis
Trimmed
Oscilator
POR and
BIAS
HB (13)
HS (14)
FEED (10)
Programming
Control
Interconnect
IO (12)
GLED (9)
+
-
V
BST
(15)
RLED (8)
IRED (2)
V
SS
(1)
Programmable
IRED Current
DS22271A-page 2
2010 Microchip Technology Inc.
RE46C190
TYPICAL BATTERY APPLICATION
V
DD
R1
Battery
3V
100
C1
10 µF
C2
1 µF
Push-to-Test/
Hush
L1
10 µH
RE46C190
D1
1
V
SS
V
BST
LX
16
V
BST
15
HS
14
HB
13
IO
12
IRCAP
11
FEED
10
GLED
9
C6
33 µF
R5
330
To other Units
C5
R4
1.5M 1 nF
R3
200K
C4
4.7 µF
V
BST
R7
100
R6
330
D4
RED
D5
GREEN
TP1
C3
100 µF
2 IRED
3
V
DD
TP2
Smoke
Chamber
D2
D3
4
TEST
5
TEST2
6
IRP
7
IRN
8
RLED
Note 1:
C2 should be located as close as possible to the device power pins, and C1 should be located as close
as possible to V
SS
.
2:
R3, R4 and C5 are typical values and may be adjusted to maximize sound pressure.
3:
DC-DC converter in High Boost mode (nominal V
BST
= 9.6V) can draw current pulses of greater than 1A,
and is therefore very sensitive to series resistance. Critical components of this resistance are the
inductor DC resistance, the internal resistance of the battery and the resistance in the connections from
the inductor to the battery, from the inductor to the LX pin and from the V
SS
pin to the battery. In order to
function properly under full load at V
DD
= 2V, the total of the inductor and interconnect resistances should
not exceed 0.3
.
The internal battery resistance should be no more than 0.5
and a low ESR capacitor
of 10 µF or more should be connected in parallel with the battery, to average the current draw over the
boost converter cycle.
4:
Schottky diode D1 must have a maximum peak current rating of at least 1.5A. For best results it should
have forward voltage specification of less than 0.5V at 1A, and low reverse leakage.
5:
Inductor L1 must have a maximum peak current rating of at least 1.5A.
2010 Microchip Technology Inc.
DS22271A-page 3
RE46C190
NOTES:
DS22271A-page 4
2010 Microchip Technology Inc.
RE46C190
1.0
ELECTRICAL
CHARACTERISTICS
† Notice:
Stresses above those listed under “Maximum
ratings” may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at
these or any other conditions above those indicated in the
operation listings of this specification is not implied. Exposure
to maximum rating conditions for extended periods may affect
device reliability.
Absolute Maximum Ratings†
Supply Voltage .....................................V
DD
=5.5V; V
BST
=13V
Input Voltage Range Except FEED, TEST..... V
IN
= -.3V to V
DD
+.3V
FEED Input Voltage Range ..................... V
INFD
=-10 to +22V
TEST Input Voltage Range ......... V
INTEST
=-.3V to V
BST
+.3V
Input Current except FEED ................................... I
IN
= 10 mA
Continuous Operating Current (HS, HB, V
BST
)...... I
O
= 40 mA
Continuous Operating Current (IRED) ...............I
OIR
= 300 mA
Operating Temperature ...............................T
A
= -10 to +60°C
Storage Temperature ............................T
STG
= -55 to +125°C
ESD Human Body Model .................................. V
HBM
= 750V
ESD Machine Model .............................................V
MM
= 75V
DC ELECTRICAL CHARACTERISTICS
DC Electrical Characteristics:
Unless otherwise indicated, all parameters apply at T
A
= -10 to +60°C, V
DD
= 3V,
V
BST
= 4.2V, Typical Application (unless otherwise noted)(Note
1, Note 2, Note 3)
Parameter
Supply Voltage
Supply Current
Symbol
V
DD
I
DD1
Test
Pin
3
3
Min
2
—
Typ
—
1
Max
5.0
2
Units
V
µA
Conditions
Operating
Standby, Inputs low,
No loads, Boost Off, No
smoke check
Standby, Inputs low,
No loads, Boost Off, No
smoke check
During smoke check
IRCAP charging for Smoke
Check, GLED operation
I
OUT
= 40 mA
No local alarm,
RLED Operation,
I
OUT
= 40 mA, IO as an
input
IRP = V
DD
or V
SS
IRN = V
DD
or V
SS
FEED = 22V; V
BST
= 9V
FEED = -10V;
V
BST
= 10.7V
FEED, V
BST
= 9V
No local alarm,
IO as an input
Standby Boost
Current
IRCAP Supply
Current
Boost Voltage
I
BST1
15
—
100
—
nA
I
IRCAP
V
BST1
11
15
—
3.0
500
3.6
—
4.2
µA
V
V
BST2
15
8.5
9.6
10.7
V
Input Leakage
I
INOP
I
IHF
I
ILF
6
7
10
10
10
12
-200
-200
—
-50
—
—
—
—
20
-15
—
—
200
200
50
—
2.7
800
pA
pA
µA
µA
V
mV
Input Voltage Low
V
IL1
V
IL2
Note 1:
2:
3:
4:
Wherever a specific V
BST
value is listed under test conditions, the V
BST
is forced externally with the
inductor disconnected and the DC-DC converter NOT running.
Typical values are for design information only.
Limits over the specified temperature range are not production tested and are based on characterization
data. Unless otherwise stated, production test is at room temperature with guardbanded limits.
Not production tested.
2010 Microchip Technology Inc.
DS22271A-page 5
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