1
LTC1042
1042fa
■
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
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, V
IN
, is inside the window the WITHIN WINDOW
output is high. The ABOVE WINDOW output is high
whenever V
IN
is above the window. By interchanging V
IN
and CENTER, the ABOVE WINDOW output becomes
BELOW WINDOW and is high if V
IN
is below the window.
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.
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 compara-
tors. 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.
Window Comparator
■
Fault Detectors
■
Go/No-Go Testing
■
Microprocessor Power Supply Monitor
LTCMOS is a trademark of Linear Technology Corp.
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
0.05µF
8
7
6
5
1
2
3
4
10M ±5%
TEMPERATURE
ABOVE 31°F
±1°F
“HI” =
TEMPERATURE
BETWEEN
26°F AND 31°F
±1°F
“HI” =
3V TO 16V
LTC1042 • A01
I
T
V
+
LTC1042
R2*
576Ω
R1*
7.5k
150k 150k
T
Battery-Powered Remote Freezer Alarm Total Supply Current
vs Sampling Frequency
SAMPLING FREQUENCY, f
S
(Hz)
0.1
0.01
TOTAL SUPPLY CURRENT, I
T
(µA)
0.1
1
10
100
1000
10000
110100 1000
LTC1042 • TA02
10000
V
+
= 6V
FOR THIS APPLICATION
f
S
≈ 1HZ
I
T
LTC1042 SUPPLY
CURRENT
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
, LTC and LT are registered trademarks of Linear Technology Corporation.
