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PDF MAX931 Data sheet ( Hoja de datos )
| Número de pieza | MAX931 | |
| Descripción | Ultra Low-Power / Low-Cost Comparators with 2eference | |
| Fabricantes | Maxim Integrated | |
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19-0194; Rev 1; 2/97
Ultra Low-Power, Low-Cost
Comparators with 2% Reference
_______________General Description
The MAX931-MAX934 single, dual, and quad micropower,
low-voltage comparators plus an on-board 2% accurate
reference feature the lowest power consumption available.
These comparators draw less than 4µA supply current
over temperature (MAX931), and include an internal
1.182V ±2% voltage reference, programmable hysteresis,
and TTL/CMOS outputs that sink and source current.
Ideal for 3V or 5V single-supply applications, the
MAX931-MAX934 operate from a single +2.5V to +11V
supply (or a ±1.25V to ±5V dual supply), and each
comparator’s input voltage range extends from the
negative supply rail to within 1.3V of the positive supply.
The MAX931-MAX934’s unique output stage continuously
sources as much as 40mA. And by eliminating power-
supply glitches that commonly occur when comparators
change logic states, the MAX931-MAX934 minimize
parasitic feedback, which makes them easier to use.
The single MAX931 and dual MAX932/MAX933 provide a
unique and simple method for adding hysteresis without
feedback and complicated equations, using the HYST pin
and two resistors.
For applications that require increased precision with
similar power requirements, see the MAX921-MAX924 data
sheet. These devices include a 1% precision reference.
PART
INTERNAL
2%
REFERENCE
COMPARATORS
PER
PACKAGE
INTERNAL
HYSTERESIS
PACK-
AGE
MAX931 Yes
MAX932 Yes
MAX933 Yes
MAX934 Yes
1
2
2
4
8-Pin
Yes DIP/SO/
µMAX
8-Pin
Yes DIP/SO/
µMAX
8-Pin
Yes DIP/SO/
µMAX
No
16-Pin
DIP/SO
________________________Applications
Battery-Powered Systems
Threshold Detectors
Window Comparators
Oscillator Circuits
Alarm Circuits
____________________________Features
o Ultra-Low 4µA Max Quiescent Current
Over Extended Temp. Range (MAX931)
o Power Supplies:
Single +2.5V to +11V
Dual ±1.25V to ±5.5V
o Input Voltage Range Includes Negative Supply
o Internal 1.182V ±2% Bandgap Reference
o Adjustable Hysteresis
o TTL-/CMOS-Compatible Outputs
o 12µs Propagation Delay (10mV Overdrive)
o No Switching Crowbar Current
o 40mA Continuous Source Current
o Available in Space-Saving µMAX Package
______________Ordering Information
PART
MAX931CPA
MAX931CSA
MAX931CUA
MAX931EPA
MAX931ESA
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 Plastic DIP
8 SO
8 µMAX
8 Plastic DIP
8 SO
Ordering Information continued on last page.
For similar devices guaranteed over the military temp. range, see
the MAX921-MAX924 data sheet. The MAX931, MAX933, and
MAX934 are pin-compatible with the 1% accurate MAX921,
MAX923, and MAX924, respectively. The MAX932 and
MAX922 are not pin-compatible.
__________Typical Operating Circuit
VIN
3 IN+
4 IN-
7
V+
OUT 8
5 HYST
6 REF
MAX931
V- GND
21
THRESHOLD DETECTOR
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
1 page  
Ultra Low-Power, Low-Cost
Comparators with 2% Reference
__________________________________________Typical Operating Characteristics
(V+ = 5V, V- = GND, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE LOW
vs. LOAD CURRENT
2.5
V+ = 5V
2.0
V+ = 3V
1.5
OUTPUT VOLTAGE HIGH vs.
LOAD CURRENT
5.0
V+ = 5V
4.5
4.0
3.5
1.190
1.185
1.180
1.175
REFERENCE OUTPUT VOLTAGE vs.
OUTPUT LOAD CURRENT
SINK
SOURCE
1.0
0.5
0.0
0
1.22
1.21
1.20
1.19
1.18
1.17
1.16
1.15
4 8 12 16
LOAD CURRENT (mA)
REFERENCE VOLTAGE
vs. TEMPERATURE
EXTENDED TEMP. RANGE
COMMERCIAL
TEMP. RANGE
20
1.14
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
MAX933
SUPPLY CURRENT vs. TEMPERATURE
5.0
IN+ = IN- +100mV
4.5
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
3.0
2.5
V+ = 3V
2.0
1.5
0
10 20 30 40
LOAD CURRENT (mA)
50
MAX931
SUPPLY CURRENT vs. TEMPERATURE
4.5
IN+ = IN- + 100mV
4.0
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
MAX934
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
1.170
1.165
1.160
1.155
0
V+ = 5V
OR
V+ = 3V
5 10 15 20 25
OUTPUT LOAD CURRENT (µA)
30
MAX932
SUPPLY CURRENT vs. TEMPERATURE
5.0
IN+ = IN- +100mV
4.5
4.0
V+ = 5V, V- = 0V
3.5
3.0
2.5
2.0
-60
10
V+ = 3V, V- = 0V
-20 20 60 100
TEMPERATURE (°C)
MAX934
SUPPLY CURRENT vs.
LOW SUPPLY VOLTAGES
IN+ = IN- +100mV
140
1
0.1
0.01
1.0
1.5 2.0
SINGLE-SUPPLY VOLTAGE (V)
2.5
_______________________________________________________________________________________ 5
5 Page 
Ultra Low-Power, Low-Cost
Comparators with 2% Reference
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.
_______________Typical Applications
Auto-Off Power Source
Figure 5 shows the schematic for a 40mA power supply
that has a timed auto power-off function. The
comparator output is the switched power-supply output.
With a 10mA load, it typically provides a voltage of
(VBATT - 0.12V), but draws only 3.5µA quiescent current.
This circuit takes advantage of the four key features of
the MAX931: 2.5µA supply current, an internal
reference, hysteresis, and high current output. Using
the component values shown, the three-resistor voltage
divider programs the maximum ±50mV of hysteresis
and sets the IN- voltage at 100mV. This gives an IN+
trip threshold of approximately 50mV for IN+ falling.
The RC time constant determines the maximum power-
on time of the OUT pin before power-down occurs.
This period can be approximated by:
R x C x 4.6sec
For example: 2MΩ x 10µF x 4.6 = 92sec. The actual
time will vary with both the leakage current of the
capacitor and the voltage applied to the circuit.
Window Detector
The MAX933 is ideal for making window detectors
(undervoltage/overvoltage detectors). The schematic
is shown in Figure 6, with component values selected
for an 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. OUTA provides an active-low undervoltage
indication, and OUTB gives an active-low overvoltage
indication. ANDing 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 (MAX931/MAX932/MAX933) 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.
2. Select R1. The leakage current into INB- is normally
under 1nA, so the current through R1 should exceed
4.5V TO 6.0V
7
V+
MOMENTARY SWITCH
6 REF
MAX931
IN+ 3
47k
5 HYST
1.1M
4 IN-
100k V-
2
CR
OUT 8
GND
1
VBATT -0.15V
10mA
VIN
R3
VOTH = 5.5V
VUTH = 4.5V
INA+
+5V
V+
OUTA
HYST
R2
R5
10k REF
OUTB
INB-
R1 R4
2.4M
V- MAX933
UNDERVOLTAGE
POWER GOOD
OVERVOLTAGE
Figure 5. Auto-off power switch operates on 2.5µA quiescent
current.
Figure 6. Window Detector
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX931.PDF ] | |
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