LTC1042_09 Datasheet, PDF (1/8 Pages) Linear Technology – Window Comparator

LTC1042
Window Comparator
FEATURES
■ _{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}
U
APPLICATIO S
■ _{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.
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, 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.
TYPICAL APPLICATIO
Battery-Powered Remote Freezer Alarm
V⁺
I_T
150k
3V TO 16V _R1*
7.5k
R2*
576Ω
150k 1
8
2
7
3 LTC1042
6
T4
5
“HI” = TEMPERATURE
10M ±5%
BETWEEN
26°F AND 31°F
±1°F
“HI” = TEMPERATURE
ABOVE 31°F
±1°F
0.05µF
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
Total Supply Current
vs Sampling Frequency
10000
1000
V⁺ = 6V
I_T
100
10
LTC1042 SUPPLY
CURRENT
1
0.1
0.01
0.1
FOR THIS APPLICATION
f_S ≈ 1HZ
1
10
100 1000 10000
SAMPLING FREQUENCY, f_S (Hz)
LTC1042 • TA02
1042fa
1