LTC1042
Window Comparator
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FEATURES
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DESCRIPTIO
The LTC®1042 is a monolithic CMOS window comparator
manufactured using Linear Technology’s enhanced
LTCMOS™ silicon gate process. Two high impedance
voltage inputs, CENTER and WIDTH/2, define the middle
and width of the comparison window. Whenever the input
voltage, VIN, is inside the window the WITHIN WINDOW
output is high. The ABOVE WINDOW output is high
whenever VIN is above the window. By interchanging VIN
and CENTER, the ABOVE WINDOW output becomes
BELOW WINDOW and is high if VIN is below the window.
Micropower 1.5µW (1 Sample/Second)
Wide Supply Range — 2.8V to 16V
High Accuracy
Center Error ±1mV Max
Width Error ±0.15% Max
Wide Input Voltage Range
V+ to Ground
TTL Outputs with 5V Supply
Two Independent Ground-Referred Control Inputs
Small Size 8-Pin MiniDIP
Sampling techniques provide high impedance voltage
inputs that can common mode to both supply rails
(V+ and GND). An important feature of the inputs is their
non-interaction. Also the device is effectively “chopper
stabilized,” giving it extremely high accuracy over
all conditions of temperature, power supply and input
voltage range.
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APPLICATIO S
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Fault Detectors
Go/No-Go Testing
Microprocessor Power Supply Monitor
, LTC and LT are registered trademarks of Linear Technology Corporation.
LTCMOS is a trademark of Linear Technology Corp.
Another benefit of the sampling techniques used to design
the LTC1042 is the extremely low power consumption.
When the device is strobed, it internally turns on the power
to the comparators, samples the inputs, stores the outputs
in CMOS latches and then turns off power to the comparators. This all happens in about 80µs. Average power can be
made small, almost arbitrarily, by lowering the strobe rate.
The device can be self-strobed using an external RC
network or strobed externally by driving the OSC pin with
a CMOS gate.
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TYPICAL APPLICATIO
Battery-Powered Remote Freezer Alarm
Total Supply Current
vs Sampling Frequency
V+
10000
150k
1
8
2
150k
7
3
3V TO 16V
R1*
7.5k
T
4
LTC1042
“HI” = TEMPERATURE
BETWEEN
10M ±5%
26°F AND 31°F
±1°F
6
“HI” = TEMPERATURE
ABOVE 31°F
±1°F
5
0.05µF
R2*
576Ω
V+ = 6V
TOTAL SUPPLY CURRENT, IT (µA)
IT
1000
IT
100
10
LTC1042 SUPPLY
CURRENT
1
FOR THIS APPLICATION
fS ≈ 1HZ
0.1
0.01
T = YELLOW SPRINGS INSTRUMENT CO., INC. P/N 44007
ALL RESISTORS ±1% UNLESS OTHERWISE SPECIFIED
*OTHER TEMPERATURE BANDS MAY BE SELECTED BY CHOOSING APPROPRIATE VALUES FOR R1 AND R2
LTC1042 • A01
0.1
1
10
100
1000
SAMPLING FREQUENCY, fS (Hz)
10000
LTC1042 • TA02
1042fa
1
