Datasheet

by the high-input-impedance op amp of a MAX951
(Figure 6). The comparator and resistor voltage divider
set an alarm threshold to indicate a fire.
Design and fabrication of the connection from the inter-
mediate plate of the ionization chamber to the nonin-
verting input of the op amp is critical, since the
impedance of this node must be well above 50MΩ. This
connection must be as short and direct as possible to
prevent charge leakage and 60Hz interference. Where
possible, the grounded outer electrode or chassis of
the ionization chamber should shield this connection to
reduce 60Hz interference. Pay special attention to
board cleaning, to prevent leakage due to ionic com-
pounds such as chlorides, flux, and other contaminants
from the manufacturing process. Where applicable, a
coating of high-purity wax may be used to insulate this
connection and prevent leakage due to surface mois-
ture or an accumulation of dirt.
0.084"
(2.134mm)
0.058"
(1.473mm)
V
DD
V
SS
COMPOUT
REF(COMPIN-)
COMPIN+
AMPIN+
( ) ARE FOR MAX953/MAX954
AMPIN-
AMPOUT
MAX951–MAX954
Ultra-Low-Power, Single-Supply
Op Amp + Comparator + Reference
*Dice are tested at T
A
= +25°C, DC parameters only.
**Contact factory for availability and processing to MIL-STD-883.
TRANSISTOR COUNT: 163
SUBSTRATE CONNECTED TO V
DD
3
AMPIN+
INPUT
2
5
6
1
8
4
REF
0.1µF
1.20V
V
SS
V
CC
R1
R2
1MΩ
COMPOUT
7
MAX951
MAX952
__________Typical Operating Circuit
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Chip Topography
Chip Information
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX951C/D 0°C to +70°C Dice*
MAX951EPA -40°C to +85°C 8 Plastic Dip
MAX951ESA -40°C to +85°C 8 SO
MAX951EUA -40°C to +85°C 8 µMAX
MAX951MJA -55°C to +125°C 8 CERDIP**
MAX952C/D 0°C to +70°C Dice*
MAX952EPA -40°C to +85°C 8 Plastic Dip
MAX952ESA -40°C to +85°C 8 SO
MAX952EUA -40°C to +85°C 8 µMAX
MAX952MJA -55°C to +125°C 8 CERDIP**
MAX953C/D 0°C to +70°C Dice*
MAX953EPA -40°C to +85°C 8 Plastic Dip
MAX953ESA -40°C to +85°C 8 SO
MAX953EUA -40°C to +85°C 8 µMAX
MAX953MJA -55°C to +125°C 8 CERDIP**
MAX954C/D 0°C to +70°C Dice*
MAX954EPA -40°C to +85°C 8 Plastic Dip
MAX954ESA -40°C to +85°C 8 SO
MAX954EUA -40°C to +85°C 8 µMAX
MAX954MJA -55°C to +125°C 8 CERDIP**
Package Information
For the latest package outline information, go to
www.maxim-ic.com/packages.