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PDF MAX973 Data sheet ( Hoja de datos )
| Número de pieza | MAX973 | |
| Descripción | (MAX971 - MAX984) Single/Dual-Supply Comparators | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-0450; Rev 3; 2/03
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
General Description
The MAX971–MAX974 and MAX981–MAX984 single/
dual/quad low-voltage comparators feature the lowest
power consumption available. These micropower
devices draw less than 4µA supply current over
temperature (MAX971/MAX972/MAX981/MAX982), and
include an internal 1.182V ±1% (MAX971/MAX973/
MAX974) or ±2% (MAX981–MAX984) voltage reference
and programmable hysteresis.
Ideal for 3V or 5V single-supply applications, these
devices operate from a single 2.5V to 11V supply (or
±1.25V to ±5.5V dual supplies), and each comparator’s
input voltage ranges from the negative supply rail to within
1.3V of the positive supply.
The single MAX971/MAX981 and the dual MAX973/
MAX982/MAX983 provide a unique, simple method for
adding hysteresis without feedback or complicated
equations, simply by using the HYST pin plus two
resistors.
The MAX971–MAX974 and MAX981–MAX984’s open-
drain outputs permit wire-ORed configurations. Thanks to
an 11V output range and separate GND pin for the output
transistor (MAX971/MAX974, MAX981/MAX984), these
devices are ideal for level translators and bipolar to single-
ended converters. For similar devices with complementary
output stages, see the MAX921–MAX924 (1% reference)
and the MAX931–MAX934 (2% reference).
MAX971
1%
1
Yes
8-Pin
DIP/SO/µMAX
MAX972 None
2
No
8-Pin UCSP/
DIP/SO/µMAX
MAX973
1%
2
Yes
8-Pin
DIP/SO/µMAX
MAX974
1%
4
No 16-Pin DIP/SO
MAX981
MAX982
MAX983
2%
2%
2%
1
Yes
8-Pin
DIP/SO/µMAX
2
Yes
8-Pin
DIP/SO/µMAX
2
Yes
8-Pin
DIP/SO/µMAX
MAX984
2%
4
No 16-Pin DIP/SO
Features
o Available in Ultra-Small Packages:
UCSP™ (MAX972)
µMAX (MAX9_1/MAX9_2/MAX9_3)
o Ultra-Low Quiescent Current (4µA, max)
Over Extended Temp Range (MAX971/MAX981)
o Power Supplies:
Single 2.5V to 11V
Dual ±1.25V to ±5.5V
o Input Voltage Range Includes Negative Supply
o Internal Bandgap Reference
1.182V ±1% (MAX97_)
1.182V ±2% (MAX98_)
o 12µs Propagation Delay (10mV Overdrive)
o Output Has Separate GND Pin (MAX9_1/MAX9_4)
Applications
Battery-Powered
Systems
Threshold Detectors
Window Comparators
Level Translators
Oscillator Circuits
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX971CPA
0°C to +70°C
8 Plastic Dip
MAX971CSA
0°C to +70°C
8 SO
MAX971CUA
0°C to +70°C
8 µMAX
Ordering Information continued at end of data sheet.
Typical Operating Circuit
VIN
7
V+
3 IN+
4 IN-
OUT 8
5 HYST
6 REF
V-
2
MAX971
MAX981
GND
1
THRESHOLD DETECTOR
UCSP is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________________________________ 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Free Datasheet http://www.datasheet4u.com/
1 page  
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
__________________________________________Typical Operating Characteristics
(V+ = 5V, V- = GND = 0V, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE LOW
vs. LOAD CURRENT
2.5
V+ = 5V
2.0
V+ = 3V
1.5
1.190
1.185
1.180
1.175
REFERENCE OUTPUT VOLTAGE vs.
OUTPUT LOAD CURRENT
SINK
SOURCE
1.0 1.170
1.165
0.5
1.160
V+ = 5V
OR
V+ = 3V
0
0
1.155
4 8 12 16 20
0 5 10 15 20 25 30
LOAD CURRENT (mA)
OUTPUT LOAD CURRENT (µA)
MAX9_1
SUPPLY CURRENT vs.
TEMPERATURE
4.5
IN+ = IN- + 100mV
MAX972
SUPPLY CURRENT vs. TEMPERATURE
4.5
IN+ = (IN- + 100mV)
4.0 4.0
MAX971/MAX973/MAX974
REFERENCE VOLTAGE vs. TEMPERATURE
1.22
1.21
EXTENDED TEMP RANGE
1.20
1.19 COMMERCIAL
TEMP RANGE
1.18
1.17
1.16
1.15
1.14
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
MAX982/MAX9_3
SUPPLY CURRENT vs. TEMPERATURE
5.0
4.5
V+ = 5V, V- = - 5V
3.5
3.0
V+ = 3V, V- = 0V
2.5
2.0
-60
V+ = 5V, V- = 0V
-20 20 60 100
TEMPERATURE (°C)
140
3.5
V+ = 10V, V- = 0V
3.0
2.5
2.0
1.5
-60
V+ = 5V, V- = 0V
V+ = 3V, V- = 0V
-20 20 60 100
TEMPERATURE (°C)
140
4.0
V+ = 5V, V- = 0V
3.5
3.0
2.5
2.0
-60
V+ = 3V, V- = 0V
-20 20 60 100
TEMPERATURE (°C)
140
MAX9_4
SUPPLY CURRENT vs. TEMPERATURE
10
IN+ = (IN- + 100mV)
9
8
7
V+ = 5V, V- = -5V
6
5 V+ = 5V, V- = 0V
4 V+ = 3V, V- = 0V
3
-60
-20 20 60 100
TEMPERATURE (°C)
140
MAX9_4
SUPPLY CURRENT vs.
LOW SUPPLY VOLTAGES
10
1
0.1
0.01
1.0
1.5 2.0
SINGLE-SUPPLY VOLTAGE (V)
2.5
MAX9_1/MAX982/MAX9_3
HYSTERESIS CONTROL
80
60
OUTPUT HIGH
40
20
0 NO CHANGE
-20
-40
OUTPUT LOW
-60
-80
0
10 20 30 40
VREF - VHYST (mV)
50
_______________________________________________________________________________________ 5
Free Datasheet http://www.datasheet4u.com/
5 Page 
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
__________Applications Information
Hysteresis
Hysteresis increases the comparators’ noise margin by
increasing the upper threshold and decreasing the
lower threshold (Figure 2).
Hysteresis (MAX9_1/MAX982/MAX9_3)
To add hysteresis to the MAX9_1, MAX982, or MAX9_3,
connect resistor R1 between REF and HYST, and
connect resistor R2 between HYST and V- (Figure 3). If
no hysteresis is required, connect HYST to REF. When
hysteresis is added, the upper threshold increases by
the same amount that the lower threshold decreases.
The hysteresis band (the difference between the upper
and lower thresholds, VHB) is approximately equal to
twice the voltage between REF and HYST. The HYST
input can be adjusted to a maximum voltage of REF
and to a minimum voltage of (REF - 50mV). The
maximum difference between REF and HYST (50mV)
will therefore produce a 100mV (max) hysteresis band.
Use the following equations to determine R1 and R2:
( )R1 =
VHB
2 × IREF
1.182 –
VHB
2
R2 =
IREF
where IREF (the current sourced by the reference)
should not exceed the REF source capability, and
should be significantly larger than the HYST input
current. IREF values between 0.1µA and 4µA are usually
appropriate. If 2.4MΩ is chosen for R2 (IREF = 0.5µA),
the equation for R1 and VHB can be approximated as:
R1 (kΩ) = VHB (mV)
When hysteresis is obtained in this manner for the
MAX982/MAX9_3, the same hysteresis applies to both
comparators.
Hysteresis (MAX972/MAX9_4)
Hysteresis can be implemented with any comparator
using positive feedback, as shown in Figure 4. This
approach generally draws more current than circuits
using the HYST pin on the MAX9_1/MAX982/MAX9_3,
and the high feedback impedance slows hysteresis. In
addition, because the output does not source current,
any increase in the upper threshold is dependent on
the load or pullup resistor on the output.
V+
RH
VIN RPULLUP
V+ OUT
MAX9_4 V-
GND
VREF
Figure 4. External Hysteresis
Board Layout and Bypassing
Power-supply bypass capacitors are not needed if the
supply impedance is low, but 100nF bypass capacitors
should be used when the supply impedance is high or
when the supply leads are long. Minimize signal lead
lengths to reduce stray capacitance between the input
and output that might cause instability. Do not bypass
the reference output.
Window Detector
The MAX9_3 is ideal for making window detectors
(undervoltage/overvoltage detectors). The schematic is
shown in Figure 5, with component values selected for a
4.5V undervoltage threshold and a 5.5V overvoltage
threshold. Choose different thresholds by changing the
values of R1, R2, and R3. To prevent chatter at the
output when the supply voltage is close to a threshold,
hysteresis has been added using R4 and R5. Taken
alone, OUTA would provide an active-low undervoltage
indication, and OUTB would give an active-low
overvoltage indication. Wired-ORing the two outputs
provides an active-high, power-good signal.
The design procedure is as follows:
1) Choose the required hysteresis level and calculate
values for R4 and R5 according to the formulas in
the Hysteresis (MAX9_1/MAX982/MAX9_3) section.
In this example, ±5mV of hysteresis has been added
at the comparator input (VH = VHB/2). This means
that the hysteresis apparent at VIN will be larger
because of the input resistor divider.
______________________________________________________________________________________ 11
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11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MAX973.PDF ] | |
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