R&E International
A Subsidiary of Microchip Technology Inc.
RE46C112
Ionization Smoke Detector IC
Product Specification
General Description
The RE46C112 is an ionization type smoke detector IC.
It is intended for applications using ionization type
chambers to detect smoke. When enabled, VOUT is ¼
of either the DETECT input or VDD depending on the
status of the SELECT input. When the Select input is
allowed to float the circuit is in the low current mode
with only the guard amplifier enabled.
Utilizing low power CMOS technology the RE46C112
was designed for use in smoke detectors that comply
with Underwriters Laboratory Specification UL217.
Features
•
•
•
•
•
•
•
Guard Outputs for Ion Detector Input
± 0.75pA Detect Input Current
Microprocessor A/D Compatible Analog Output
Low Quiescent Current Consumption (<10uA)
Available in 8L PDIP or 8L N SOIC
2000V ESD Protection (HBM)
Available in Standard Packaging or RoHS
Compliant Pb Free Packaging
Pin Configuration
1
8
G2
DETECT
G1
VO UT
VDD
VCC
SELECT
VSS
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply Voltage
Supply Voltage
Detect Input Voltage Range
SELECT Input Voltage Range
Operating Temperature
Storage Temperature
Maximum Junction Temperature
SYMBOL
V
DD
V
CC
V
INDET
V
INSEL
T
A
T
STG
T
J
VALUE
12.5
6
V
DD
+.3
V
CC
+.3
-10 to 60
-55 to 125
150
UNITS
V
V
V
V
°C
°C
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are
stress ratings only and operation at these conditions for extended periods may affect device reliability.
This product utilizes CMOS technology with static protection; however proper ESD prevention procedures should be used
when handling this product. Damage can occur when exposed to extremely high static electrical charge
© 2009 Microchip Technology Inc.
DS22161A-page 1
RE46C112
Ionization Smoke Detector IC
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Electrical Characteristics at TA = 25°C, VDD=9V, VCC=5V, VSS=0V (unless otherwise noted)
Test
Pin
1
2
1
1
1
I
CC
2
2
Input Voltage High
Input Voltage Low
Input Leakage
V
ih
V
il
IL
det
3
3
7
Parameter
Supply Voltage
Supply Current
Symbol
V
DD
V
CC
I
DD
Test Conditions
Operating
Operating
SELECT=open, DETECT=4.5V,
VDD=9V
SELECT=open, DETECT=6V,
VDD=12V
SELECT=VCC or VSS,
DETECT=4.5V, VDD=9V
SELECT=open, VCC=5V
DETECT=4.5V, VDD=9V
SELECT=open, VCC=3V,
DETECT=6V, VDD=12V
SELECT
SELECT
VDD=12V, DETECT=VDD or
VSS, 0-40% RH
VDD=12V, DETECT=VDD or
VSS, 85% RH, See Note 1
SELECT=VCC or VSS VCC=5V
SELECT=VCC or VSS VCC=3V
Min
6
2.7
Limits
Typ
Max
12
5.5
3
4
60
2.75
1
4.5
5.5
90
4.3
1.75
0.4
Units
V
V
uA
uA
uA
uA
uA
V
V
pA
pA
uA
uA
mV
V
k
V
V
V
CC
-.4
-0.75
-1.5
-15
-4
-50
0.75
1.5
45
15
50
V
DD
-.5
10
2% +
20mV
2% +
20mV
IL
sel
3
Offset Voltage
Common Mode Voltage
Output Impedance
Output Voltage
VG
OS
V
CM
6,8
7
6,8
Guard Amplifier
Guard Amplifier
VDD=6V to 12V,
SELECT=VSS, RL=10K
DETECT= 2V to VDD-.5V,
SELECT=VCC, RL=10K
2
V
out
5
5
-2% -
20mV
-2% -
20mV
.25*V
DD
.25*V
DETECT
Note 1: Sample test only
© 2009 Microchip Technology Inc.
DS22161A-page 2
RE46C112
Ionization Smoke Detector IC
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
PIN DESCRIPTIONS
PIN 1 (VDD) -
This pin should be connected to the most positive supply potential, typically a 9 Volt battery. The
VDD voltage can range between 6V and 12V with respect to VSS. Reverse battery protection must be provided
externally.
PIN 2 (VCC)
– This positive supply potential can range between 2.7V and 5.5V with respect to VSS and must be
less than the VDD voltage. This pin is usually connected to a microprocessor positive supply voltage.
PIN 3 (SELECT)
– This input pin determines the function of VOUT. This pin is typically driven by a
microprocessor port. The input high level should not exceed VCC. If left floating VOUT is inactive and pulled
internally to VSS. If SELECT is at the VIL (low) level then VOUT is nominally ¼ of the VDD voltage. If SELECT is
at the VIH level (high) then VOUT is nominally ¼ of the DETECT voltage.
PIN 4 (VSS)
– This pin is the negative supply potential and is usually connected to ground.
PIN 5 (VOUT)
– This analog output is a representation of VDD or DETECT or is at VSS depending on the status
of the SELECT input. Typically this output is connected to a microprocessor A to D input to monitor the status of
the supply voltage and the ionization chamber voltage.
PIN 6, 8 (G1, G2)
– These pins are connected to the internal guard amplifier output and are within ±50mV of the
DETECT input. These outputs are always active and help to minimize surface leakage to the DETECT pin.
PIN 7 (DETECT)
- This input is typically interfaced to an ionization chamber to sense the presence of smoke.
Input leakage is less than ±.75pA on this input.
© 2009 Microchip Technology Inc.
DS22161A-page 3
RE46C112
Ionization Smoke Detector IC
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Functional Block Diagram
Figure 1
© 2009 Microchip Technology Inc.
DS22161A-page 4
RE46C112
Ionization Smoke Detector IC
Product Specification
R&E International
A Subsidiary of Microchip Technology Inc.
Typical Application
Figure 2
© 2009 Microchip Technology Inc.
DS22161A-page 5
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