MAX931-MAX934 [MAXIM]
Ultra Low-Power, Low-Cost Comparators with 2eference; 超低功耗，低成本比较有2eference
| 型号： | MAX931-MAX934 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Ultra Low-Power, Low-Cost Comparators with 2eference |
| 文件： | 总16页 (文件大小：166K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0194; Rev 1; 2/97
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
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
ove r te mp e ra ture (MAX931), a nd inc lud e a n inte rna l
1.182V ±2% voltage reference, programmable hysteresis,
and TTL/CMOS outputs that sink and source current.
♦ Ultra-Low 4µA Max Quiescent Current
Over Extended Temp. Range (MAX931)
♦ Power Supplies:
Single +2.5V to +11V
Dual ±1.25V to ±5.5V
♦ Input Voltage Range Includes Negative Supply
♦ Internal 1.182V ±2% Bandgap Reference
♦ Adjustable Hysteresis
Id e a l for 3V or 5V s ing le -s up p ly a p p lic a tions , the
MAX931-MAX934 operate from a single +2.5V to +11V
s up p ly (or a ± 1.25V to ± 5V d ua l s up p ly), a nd e a c h
c omp a ra tor’s inp ut volta g e ra ng e e xte nd s from the
negative supply rail to within 1.3V of the positive supply.
♦ TTL-/CMOS-Compatible Outputs
♦ 12µs Propagation Delay (10mV Overdrive)
♦ No Switching Crowbar Current
The MAX931-MAX934’s unique output stage continuously
sources as much as 40mA. And by eliminating power-
supply glitches that commonly occur when comparators
c ha ng e log ic s ta te s , the MAX931-MAX934 minimize
parasitic feedback, which makes them easier to use.
♦ 40mA Continuous Source Current
♦ Available in Space-Saving µMAX Package
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.
______________Ord e rin g In fo rm a t io n
PART
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
MAX931CPA
MAX931CSA
MAX931CUA
MAX931EPA
MAX931ESA
For applications that require increased precision with
similar power requirements, see the MAX921-MAX924 data
sheet. These devices include a 1% precision reference.
8 µMAX
8 Plastic DIP
8 SO
INTERNAL COMPARATORS
INTERNAL
HYSTERESIS
PACK-
AGE
Ordering Information continued on last page.
PART
2%
PER
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.
REFERENCE
PACKAGE
8-Pin
DIP/SO/
µMAX
MAX931
MAX932
Yes
Yes
1
2
Yes
Yes
8-Pin
DIP/SO/
µMAX
__________Typ ic a l Op e ra t in g Circ u it
8-Pin
DIP/SO/
µMAX
V
IN
MAX933
MAX934
Yes
Yes
2
4
Yes
No
7
V+
3
4
5
6
IN+
16-Pin
DIP/SO
OUT
8
IN-
________________________Ap p lic a t io n s
Battery-Powered Systems
Threshold Detectors
HYST
REF
MAX931
Window Comparators
V-
GND
2
1
Oscillator Circuits
Alarm Circuits
THRESHOLD DETECTOR
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
ABSOLUTE MAXIMUM RATINGS
V+ to V-, V+ to GND, GND to V-................................-0.3V, +12V
Inputs
Continuous Power Dissipation (T = +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ...727mW
A
Current, IN_+, IN_-, HYST...............................................20mA
Voltage, IN_+, IN_-, HYST................(V+ + 0.3V) to (V- – 0.3V)
Outputs
Current, REF....................................................................20mA
Current, OUT_.................................................................50mA
Voltage, REF ....................................(V+ + 0.3V) to (V- – 0.3V)
Voltage, OUT_ (MAX931/934) .....(V+ + 0.3V) to (GND – 0.3V)
Voltage, OUT_ (MAX932/933)..........(V+ + 0.3V) to (V- – 0.3V)
OUT_ Short-Circuit Duration (V+ ≤ 5.5V) ...............Continuous
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
16-Pin Plastic DIP (derate 10.53mW/°C above +70°C)..842mW
16-Pin SO (derate 8.70mW/°C above +70°C) ................696mW
Operating Temperature Ranges:
MAX93_C_ _ .......................................................0°C to +70°C
MAX93_E_ _.....................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
1-MAX934
ELECTRICAL CHARACTERISTICS—5V Operation
(V+ = 5V, V- = GND = 0V, T = T
A
to T , unless otherwise noted.)
MAX
MIN
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
POWER REQUIREMENTS
Supply Voltage Range
(Note 1)
2.5
11
V
T
= +25°C
2.5
3.1
3.1
5.5
3.2
A
MAX931,
HYST = REF
C/E temp. ranges
= +25°C
4
T
A
4.5
6
MAX932,
HYST = REF
C/E temp. ranges
= +25°C
Supply Current
IN+ = IN- + 100mV
µA
T
A
4.5
6
MAX933,
HYST = REF
C/E temp. ranges
= +25°C
T
6.5
8.5
A
MAX934
C/E temp. ranges
COMPARATOR
Input Offset Voltage
V
= 2.5V
±10
±5
mV
nA
CM
Input Leakage Current (IN-, IN+)
Input Leakage Current (HYST)
IN+ = IN- = 2.5V, C/E temp. ranges
MAX931, MAX932, MAX933
±0.01
±0.02
nA
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
Voltage Noise
V-
V+ – 1.3
1.0
V
V- to (V+ – 1.3V)
0.1
0.1
20
mV/V
mV/V
V+ = 2.5V to 11V
1.0
100Hz to 100kHz
µV
RMS
Hysteresis Input Voltage Range
MAX931, MAX932, MAX933
REF – 0.05
REF
V
Overdrive = 10mV
Overdrive = 100mV
12
4
Response Time
T
A
= +25°C, 100pF load
µs
2
_______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
ELECTRICAL CHARACTERISTICS—5V Operation (continued)
(V+ = 5V, V- = GND = 0V, T = T
A
to T , unless otherwise noted.)
MAX
MIN
PARAMETER
CONDITIONS
= 17mA
MIN
TYP
MAX UNITS
Output High Voltage
C/E temp. ranges, I
V+ – 0.4
V
OUT
MAX932,
MAX933
V- + 0.4
GND + 0.4
C/E temp. ranges,
Output Low Voltage
V
I
= 1.8mA
OUT
MAX931,
MAX934
REFERENCE
C temp. range
E temp. range
1.158
1.182
25
1.206
1.217
Reference Voltage
V
1.147
15
T
= +25°C
A
Source Current
µA
µA
C/E temp. ranges
= +25°C
6
T
A
8
4
15
Sink Current
C/E temp. ranges
100Hz to 100kHz
Voltage Noise
100
µV
RMS
Note 1: MAX934 comparators work below 2.5V, see Low-Voltage Operation section for more details.
ELECTRICAL CHARACTERISTICS—3V Operation
(V+ = 3V, V- = GND = 0V, T = T
A
to T , unless otherwise noted.)
MAX
MIN
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
POWER REQUIREMENTS
T
= +25°C
2.4
3.4
3.4
5.2
3.0
3.8
4.3
5.8
4.3
5.8
6.2
8.0
A
MAX931,
HYST = REF
C/E temp. ranges
= +25°C
T
A
MAX932,
HYST = REF
C/E temp. ranges
= +25°C
Supply Current
IN+ = (IN- + 100mV)
µA
T
A
MAX933,
HYST = REF
C/E temp. ranges
= +25°C
T
A
MAX934
C/E temp. ranges
COMPARATOR
Input Offset Voltage
V
= 1.5V
±10
±1
mV
nA
nA
CM
Input Leakage Current (IN-, IN+)
Input Leakage Current (HYST)
IN+ = IN- = 1.5V, C/E temp. ranges
MAX931, MAX932, MAX933
±0.01
±0.02
_______________________________________________________________________________________
3
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
ELECTRICAL CHARACTERISTICS—3V Operation (continued)
(V+ = 3V, V- = GND = 0V, T = T
A
to T , unless otherwise noted.)
MAX
MIN
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
Voltage Noise
V-
V+ – 1.3
V
V- to (V+ – 1.3V)
V+ = 2.5V to 11V
100Hz to 100kHz
0.2
0.1
20
1
1
mV/V
mV/V
µV
RMS
Hysteresis Input Voltage Range
MAX931, MAX932, MAX933
REF – 0.05
V+ – 0.4
REF
V
Overdrive = 10mV
Overdrive = 100mV
14
5
Response Time
T
A
= +25°C, 100pF load
µs
Output High Voltage
C/E temp. ranges, I
= 10mA
V
V
OUT
MAX932,
MAX933
V- + 0.4
1-MAX934
Output Low Voltage
C/E temp. ranges, I
= 0.8mA
OUT
MAX931
GND + 0.4
REFERENCE
C temp. range
E temp. range
1.158
1.182
25
1.206
1.217
Reference Voltage
V
1.147
T
A
= +25°C
15
6
Source Current
µA
µA
C/E temp. ranges
= +25°C
T
A
8
15
Sink Current
C/E temp. ranges
100Hz to 100kHz
4
Voltage Noise
100
µV
RMS
4
_______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
__________________________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(V+ = 5V, V- = GND, T = +25°C, unless otherwise noted.)
A
OUTPUT VOLTAGE LOW
vs. LOAD CURRENT
OUTPUT VOLTAGE HIGH vs.
LOAD CURRENT
REFERENCE OUTPUT VOLTAGE vs.
OUTPUT LOAD CURRENT
2.5
2.0
5.0
1.190
V+ = 5V
SINK
V+ = 5V
4.5
4.0
1.185
1.180
V+ = 3V
SOURCE
1.5
1.0
3.5
3.0
2.5
2.0
1.5
1.175
1.170
1.165
1.160
1.155
V+ = 3V
V+ = 5V
OR
0.5
0.0
V+ = 3V
0
4
8
12
16
20
0
10
20
30
40
50
0
5
10
15
20
25
30
LOAD CURRENT (mA)
LOAD CURRENT (mA)
OUTPUT LOAD CURRENT (µA)
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX931
MAX932
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
1.22
1.21
4.5
5.0
4.5
IN+ = IN- + 100mV
IN+ = IN- +100mV
4.0
3.5
3.0
EXTENDED TEMP. RANGE
1.20
1.19
4.0
3.5
3.0
2.5
2.0
V+ = 5V, V- = - 5V
COMMERCIAL
TEMP. RANGE
V+ = 5V, V- = 0V
1.18
1.17
V+ = 3V, V- = 0V
1.16
1.15
2.5
2.0
V+ = 3V, V- = 0V
20 60
V+ = 5V, V- = 0V
-20 20
1.14
-60
60
100
140
-60
-20
100
140
-60 -40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MAX934
MAX934
MAX933
SUPPLY CURRENT vs.
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
LOW SUPPLY VOLTAGES
10
9
5.0
10
IN+ = (IN- + 100mV)
IN+ = IN- +100mV
IN+ = IN- +100mV
4.5
4.0
8
1
V+ = 5V, V- = 0V
7
V+ = 5V, V- = -5V
3.5
3.0
2.5
2.0
6
0.1
V+ = 5V, V- = 0V
V+ = 3V, V- = 0V
5
4
V+ = 3V, V- = 0V
3
0.01
-60
-20
20
60
100
140
-60
-20
20
60
100
140
1.0
1.5
2.0
2.5
TEMPERATURE (°C)
TEMPERATURE (°C)
SINGLE-SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
____________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(V+ = 5V, V- = GND, T = +25°C, unless otherwise noted.)
A
RESPONSE TIME vs.
LOAD CAPACITANCE
HYSTERESIS CONTROL
TRANSFER FUNCTION
80
60
5.0
4.5
18
16
100k
V
0
OUTPUT HIGH
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
10µF
40
20
14
12
V
OHL
NO CHANGE
0
10
8
-20
V
OLH
-40
-60
6
4
OUTPUT LOW
1-MAX934
-80
2
0
10
20
-V
30
(mV)
40
50
-0.3
-0.1
0.1
0.2
0.3
-0.2
0
0
20
40
60
80
100
V
IN+ INPUT VOLTAGE (mV)
REF HYST
LOAD CAPACITANCE (nF)
RESPONSE TIME FOR VARIOUS
INPUT OVERDRIVES
RESPONSE TIME FOR VARIOUS
INPUT OVERDRIVES
MAX934 RESPONSE TIME
AT LOW SUPPLY VOLTAGES
10
5
5
4
3
4
3
100mV
10mV
1
20mV
100mV
2
1
2
1
50mV
20mV
50mV
10mV
0
100
0
0
±20mV OVERDRIVE
0.1
±100mV
OVERDRIVE
0
100
0.01
-2
2
6
10
14
18
1.0
1.5
2.0
2.5
-2
2
6
10
14
18
RESPONSE TIME (µs)
SINGLE-SUPPLY VOLTAGE (V)
RESPONSE TIME (µs)
SHORT-CIRCUIT SOURCE CURRENT
vs. SUPPLY VOLTAGE
SHORT-CIRCUIT SINK CURRENT
vs. SUPPLY VOLTAGE
MAX934 OUTPUT DRIVE
AT LOW SUPPLY VOLTAGES
200
100
OUT CONNECTED TO V+
GND CONNECTED TO V-
180
160
140
120
100
80
OUT CONNECTED TO V-
SOURCE CURRENT INTO 0.75V LOAD
20
10
1
10
0
60
40
20
SINK CURRENT AT V
= 0.4V
2.0
OUT
0
0.1
0
1.0
2.0
3.0
4.0
5.0
0
5
10
1.0
1.5
2.5
TOTAL SUPPLY VOLTAGE (V)
TOTAL SUPPLY VOLTAGE (V)
SINGLE-SUPPLY VOLTAGE (V)
6
_______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
____________________________________________________________P in De s c rip t io n s
PIN
NAME
FUNCTION
MAX931 MAX932 MAX933
1
–
–
GND
OUTA
V-
Ground. Connect to V- for single-supply operation. Output swings from V+ to GND.
–
1
1
Comparator A output. Sinks and sources current. Swings from V+ to V-.
Negative supply. Connect to ground for single-supply operation (MAX931).
Noninverting comparator input
2
3
–
4
–
–
2
–
3
–
4
–
2
–
3
–
–
4
IN+
INA+
IN-
Noninverting input of comparator A
Inverting comparator input
INB+
INB-
Noninverting input of comparator B
Inverting input of comparator B
Hysteresis input. Connect to REF if not used. Input voltage range is from
5
5
5
HYST
V
to V
- 50mV.
REF
REF
6
7
8
–
6
7
–
8
6
7
–
8
REF
V+
Reference output. 1.182V with respect to V-.
Positive supply
OUT
OUTB
Comparator output. Sinks and sources current. Swings from V+ to GND.
Comparator B output. Sinks and sources current. Swings from V+ to V-.
PIN
NAME
FUNCTION
MAX934
1
2
OUTB
OUTA
V+
Comparator B output. Sinks and sources current. Swings from V+ to GND.
Comparator A output. Sinks and sources current. Swings from V+ to GND.
Positive supply
3
4
INA-
INA+
INB-
INB+
REF
Inverting input of comparator A
5
Noninverting input of comparator A
6
Inverting input of comparator B
7
Noninverting input of comparator B
8
Reference output. 1.182V with respect to V-.
Negative supply. Connect to ground for single-supply operation.
Inverting input of comparator C
9
V-
10
11
12
13
14
15
16
INC-
INC+
IND-
IND+
GND
OUTD
OUTC
Noninverting input of comparator C
Inverting input of comparator D
Noninverting input of comparator D
Ground. Connect to V- for single-supply operation.
Comparator D output. Sinks and sources current. Swings from V+ to GND.
Comparator C output. Sinks and sources current. Swings from V+ to GND.
_______________________________________________________________________________________
7
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
a s e p a ra te g round for the outp ut d rive r, a llowing
_______________De t a ile d De s c rip t io n
operation with dual supplies ranging from ±1.25V to
± 5.5V. Conne c t V- to GND whe n op e ra ting the
MAX931 and the MAX934 from a single supply. The
maximum supply voltage in this case is still 11V.
The MAX931-MAX934 comprise various combinations
of a micropower 1.182V reference and a micropower
comparator. The Typical Operating Circuit shows the
MAX931 configuration, and Figures 1a-1c show the
MAX932/MAX933/MAX934 configurations.
For proper comparator operation, the input signal can
be driven from the negative supply (V-) to within one
volt of the positive supply (V+ - 1V). The guaranteed
c ommon-mod e inp ut volta g e ra ng e e xte nd s from
V- to (V+ - 1.3V). The inputs can be taken above and
below the supply rails by up to 300mV without damage.
Each comparator continuously sources up to 40mA, and
the unique output stage eliminates crowbar glitches
during output transitions. This makes them immune to
parasitic feedback (which can cause instability) and
provides excellent performance, even when circuit-
board layout is not optimal.
Operating the MAX931 and MAX934 at ±5V provides
TTL/CMOS compatibility when monitoring bipolar input
signals. TTL compatibility for the MAX932 and MAX933
is achieved by operation from a single +5V supply.
Internal hysteresis in the MAX931/MAX932/MAX933
p rovid e s the e a s ie s t me thod for imp le me nting
hysteresis. It also produces faster hysteresis action
and consumes much less current than circuits using
external positive feedback.
1-MAX934
Lo w -Vo lt a g e Op e ra t io n : V+ = 1 V
(MAX9 3 4 On ly)
P o w e r-S u p p ly a n d In p u t S ig n a l Ra n g e s
This family of devices operates from a single +2.5V to
+11V power supply. The MAX931 and MAX934 have
The guaranteed minimum operating voltage is 2.5V (or
±1.25V). As the total supply voltage is reduced below
2.5V, the p e rforma nc e d e g ra d e s a nd the s up p ly
MAX932
OUTB
V+
OUTA
V-
8
7
1
2
MAX934
OUTB
OUTA
OUTC
OUTD
1
16
15
REF
INA+
INB+
6
5
3
4
2
3
HYST
V+
GND 14
D
A
V-
INA-
INA+
IND+
13
4
5
Figure 1a. MAX932 Functional Diagram
IND-
12
B
C
MAX933
OUTB
V+
OUTA
1
8
7
INC+
11
INB-
INB+
REF
6
7
8
V-
2
3
4
INC-
10
REF
INA+
INB-
6
5
V-
9
HYST
V-
Figure 1c. MAX934 Functional Diagram
Figure 1b. MAX933 Functional Diagram
8
_______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
current falls. The reference will not function below
As the inp ut volta g e a p p roa c he s the c omp a ra tor's
offset, the output begins to bounce back and forth; this
about 2.2V, although the comparators will continue to
operate with a total supply voltage as low as 1V. While
the MAX934 has comparators that may be used at
supply voltages below 2V, the MAX931, MAX932, and
MAX933 ma y not b e us e d with s up p ly volta g e s
significantly below 2.5V.
peaks when
V
IN
= VOS. (The lowpass filter shown on
the g ra p h a ve ra g e s out the b ounc ing , ma king the
transfer function easy to observe.) Consequently, the
comparator has an effective wideband peak-to-peak
nois e of a round 0.3mV. The volta g e re fe re nc e ha s
peak-to peak noise approaching 1mV. Thus, when a
comparator is used with the reference, the combined
peak-to-peak noise is about 1mV. This, of course, is
muc h hig he r tha n the RMS nois e of the ind ivid ua l
components. Care should be taken in the layout to
a void c a p a c itive c oup ling from a ny outp ut to the
reference pin. Crosstalk can significantly increase the
actual noise of the reference.
At low supply voltages, the comparators’ output drive is
reduced and the propagation delay increases (see
Typical Operating Characteristics ). The useful input
voltage range extends from the negative supply to a
little und e r 1V b e low the p os itive s up p ly, whic h is
s lig htly c los e r to the p os itive ra il tha n the d e vic e
op e ra ting from hig he r s up p ly volta g e s . Te s t your
prototype over the full temperature and supply-voltage
range if operation below 2.5V is anticipated.
__________Ap p lic a t io n s In fo rm a t io n
Co m p a ra t o r Ou t p u t
With 100mV of overdrive, propagation delay is typically
3µs. The Typical Operating Characteristics show the
propagation delay for various overdrive levels.
Hys t e re s is
Hysteresis increases the comparators’ noise margin by
increasing the upper threshold and decreasing the
lower threshold (see Figure 2).
The MAX931 and MAX934 output swings from V+ to
GND, s o TTL c omp a tib ility is a s s ure d b y us ing a
+5V ±10% supply. The negative supply does not affect
the output swing, and can range from 0V to -5V ±10%.
Hysteresis (MAX931/MAX932/MAX933)
To add hysteresis to the MAX931/MAX932/MAX933,
c onne c t re s is tor R1 b e twe e n REF a nd HYST, a nd
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
a nd to a minimum volta g e of (REF - 50mV). The
The MAX932 and MAX933 do not have a GND pin, and
their outputs swing from V+ to V-. Connect V- to ground
and V+ to a +5V supply to achieve TTL compatibility.
The MAX931-MAX934’s unique design achieves an
outp ut s ourc e c urre nt of more tha n 40mA a nd a
s ink c urre nt of ove r 5mA, while ke e p ing q uie s c e nt
currents in the microampere range. The output can
source 100mA (at V+ = 5V) for short pulses, as long as
the p a c ka g e 's ma ximum p owe r d is s ip a tion is not
exceeded. The output stage does not generate crowbar
switching currents during transitions, which minimizes
feedback through the supplies and helps ensure stability
without bypassing.
THRESHOLDS
IN+
Vo lt a g e Re fe re n c e
The internal bandgap voltage reference has an output
of 1.182V a b ove V-. Note tha t the REF volta g e is
referenced to V-, not to GND. Its accuracy is ±2% in
the range 0°C to +70°C. The REF output is typically
capable of sourcing 15µA and sinking 8µA. Do not
bypass the REF output. For applications that require a
1% p re c is ion re fe re nc e , s e e the MAX921-MAX924
data sheet.
HYSTERESIS
IN-
BAND
VREF - VHYST
V
HB
OUT
No is e Co n s id e ra t io n s
Although the comparators have a very high gain, useful
gain is limited by noise. This is shown in the Transfer
Function graph (see Typical Operating Characteristics).
Figure 2. Threshold Hysteresis Band
_______________________________________________________________________________________
9
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
maximum difference between REF and HYST (50mV)
will therefore produce a 100mV max hysteresis band.
Use the following equations to determine R1 and R2:
2. Choose the hysteresis voltage (VHB), the voltage
between the upper and lower thresholds. In this
example, choose VHB = 50mV.
V
3. Calculate R1.
HB
R1 =
V
2 × I
HB
(
)
REF
R1 = R3 ×
V +
V
HB
1.182 –
0.05
= 10M ×
2
R2 =
5
I
REF
= 100kΩ
Whe re IREF (the c urre nt s ourc e d b y the re fe re nc e )
s hould not e xc e e d the REF s ourc e c a p a b ility, a nd
s hould b e s ig nific a ntly la rg e r tha n the HYST inp ut
c urre nt. IREF va lue s b e twe e n 0.1µA a nd 4µA a re
us ua lly a p p rop ria te . If 2.4MΩ is c hos e n for
R2 (IREF = 0.5µA), the equation for R1 and VHB can be
approximated as:
4. Choose the threshold voltage for VIN rising (VTHR). In
this example, choose VTHR = 3V.
5. Calculate R2.
1
R2 =
V
1
1
THR
1-MAX934
−
−
(V
R1 R3
REF × R1)
R1 (kΩ) = V (mV)
HB
1
Whe n hys te re s is is ob ta ine d in this ma nne r for
the MAX932/MAX933, the same hysteresis applies to
both comparators.
=
3
1
1
−
−
(1.182 × 100k)
100k 10M
Hysteresis (MAX934)
Hysteresis can be set with two resistors using positive
feedback, as shown in Figure 4. This circuit generally
draws more current than the circuits using the HYST
pin on the MAX931/MAX932/MAX933, and the high
feedback impedance slows hysteresis. The design
procedure is as follows:
= 65.44kΩ
A 1% preferred value is 64.9kΩ.
6. Verify the threshold voltages with these formulas:
V
rising :
IN
1
1
1
V
= V
× R1 ×
+
+
THR
REF
R1
R2
R3
1. Choose R3. The leakage current of IN+ is under 1nA
(up to +85°C), so the current through R3 can be
around 100nA and still maintain good accuracy.
The current through R3 at the trip point is VREF/R3,
or 100nA for R3 = 11.8MΩ. 10MΩ is a g ood
practical value.
V
falling :
IN
R1 × V +
(
−
THR
)
V
= V
THF
R3
2.5V TO 11V
7
V+
R3
I
REF
6
5
V+
REF
R1
V
IN
R1
R2
MAX931
MAX932
MAX933
OUT
V+
V-
R2
MAX934
GND
HYST
V-
V
REF
2
Figure 4. External Hysteresis
Figure 3. Programming the HYST Pin
10 ______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
For example: 2MΩ x 10µF x 4.6 = 92sec. The actual
time will va ry with b oth the le a ka g e c urre nt of the
capacitor and the voltage applied to the circuit.
Bo a rd La yo u t a n d Byp a s s in g
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.
Win d o w De t e c t o r
The MAX933 is id e a l for ma king wind ow d e te c tors
(undervoltage/overvoltage detectors). The schematic
is shown in Figure 6, with component values selected
for a n 4.5V und e rvolta g e thre s hold , a nd 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.
_______________Typ ic a l Ap p lic a t io n s
Au t o -Off P o w e r S o u rc e
Figure 5 shows the schematic for a 40mA power supply
tha t ha s a time d a uto p owe r-off func tion. 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 s up p ly c urre nt, a n inte rna l
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 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.
The RC time constant determines the maximum power-
on time of the OUT pin before power-down occurs.
This period can be approximated by:
2. Select R1. The leakage current into INB- is normally
under 1nA, so the current through R1 should exceed
R x C x 4.6sec
MOMENTARY SWITCH
V
IN
+5V
V+
V
V
UTH
= 5.5V
= 4.5V
OTH
4.5V TO 6.0V
7
V+
R3
R2
INA+
UNDERVOLTAGE
POWER GOOD
OVERVOLTAGE
OUTA
OUTB
MAX931
IN+
3
8
6
REF
HYST
47k
R
C
5
4
R5
10k
HYST
IN-
REF
INB-
OUT
1.1M
100k
VBATT -0.15V
10mA
V-
GND
1
R1
R4
2.4M
2
MAX933
V-
Figure 6. Window Detector
Figure 5. Auto-off power switch operates on 2.5µA quiescent
current.
______________________________________________________________________________________ 11
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
100nA for the thresholds to be accurate. R1 values
up to about 10MΩ can be used, but values in the
100kΩ to 1MΩ range are usually easier to deal with.
In this example, choose R1 = 294kΩ.
The full-s c a le thre s hold (a ll LEDs on) is g ive n b y
= (R1 + R2)/R1 volts. The other thresholds are at
3/4 full scale, 1/2 full scale, and 1/4 full scale. The
output resistors limit the current into the LEDs.
V
IN
3. Ca lc ula te R2 + R3. The ove rvolta g e thre s hold
s hould b e 5.5V whe n VIN is ris ing . The d e s ig n
equation is as follows:
Le ve l S h ift e r
Figure 8 shows a circuit to shift from bipolar ±5V inputs
to TTL s ig na ls . The 10kΩ re s is tors p rote c t the
comparator inputs, and do not materially affect the
operation of the circuit.
V
OTH
R2 + R3 = R1 ×
− 1
V
+ V
H
REF
Tw o -S t a g e Lo w -Vo lt a g e De t e c t o r
Fig ure 9 s hows the MAX932 monitoring a n inp ut
5.5
(1.182 + 0.005)
= 294k ×
− 1
volta g e in two s te p s . Whe n V is hig he r tha n the
IN
LOW and FAIL thresholds, outputs are high. Threshold
c a lc ula tions a re s imila r to thos e for the wind ow-
detector application.
= 1.068MΩ
4. Calculate R2. The undervoltage threshold should
be 4.5V when V is falling. The design equation is
1-MAX934
IN
as follows:
R2
R1
(V
− V )
H
REF
V
R2 = (R1 + R2 + R3) ×
− R1
V
IN
UTH
+5V
3
(1.182 − 0.005)
= (294k + 1.068M) ×
= 62.2kΩ
− 294k
V+
4.5
MAX934
1.182V
Choose R2 = 61.9kΩ (1% standard value).
8
REF
5. Calculate R3.
V-
9
2
R3 = (R2 + R3) − R2
= 1.068M − 61.9k
182k
250k
250k
5
4
INA+
INA-
OUTA
1V
= 1.006MΩ
330Ω
330Ω
330Ω
330Ω
Choose R3 = 1MΩ (1% standard value).
7
6
INB+
INB-
6. Verify the resistor values. The equations are as
follows, evaluated for the above example.
1
OUTB
750mV
Overvoltage threshold :
(R1 + R2 + R3)
V
= (V
+ V ) ×
OTH
REF H
R1
INC+
11
16
= 5.474V.
Undervoltage threshold :
OUTC
OUTD
500mV
250mV
10 INC-
(R1 + R2 + R3)
V
= (V
− V ) ×
UTH
REF H
(R1 + R2)
13
IND+
250k
250k
15
= 4.484V,
12 IND-
R5
where the hysteresis voltage V = V
×
REF
.
H
R4
GND
14
Ba r-Gra p h Le ve l Ga u g e
The high output source capability of the MAX931 series
is useful for driving LEDs. An example of this is the
simple four-stage level detector shown in Figure 7.
Figure 7. Bar-Graph Level Gauge
12 ______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
+5V
V+
MAX934
10k
10k
INA+
INA-
V
IN
0 FOR V < 0V
+5V
V+
INA
V
INA
1 FOR V > 0V
INB
OUTA
OUTB
OUTC
R3
R2
INA+
REF
INPUT VOLTAGE FAIL
INPUT VOLTAGE LOW
INB+
INB-
V
INB
R5
R4
HYST
INB+
10k
10k
INC+
INC-
V
INC
R1
MAX932
V-
IND+
IND-
V
IND
OUTD
REF
N.C.
V-
GND
-5V
Figure 8. Level Shifter: ±5V Input to CMOS Output
Figure 9. Two-Stage Low-Voltage Detector
______________________________________________________________________________________ 13
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
_________________P in Co n fig u ra t io n s
_Ord e rin g In fo rm a t io n (c o n t in u e d )
PART
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
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
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
TOP VIEW
MAX932CPA
MAX932CSA
MAX932CUA
MAX932EPA
MAX932ESA
MAX933CPA
MAX933CSA
MAX933CUA
MAX933EPA
MAX933ESA
MAX934CPE
MAX934CSE
MAX934EPE
MAX934ESE
1
2
3
4
8
7
6
5
GND
V-
OUT
V+
8 µMAX
8 Plastic DIP
8 SO
MAX931
REF
IN+
IN-
8 Plastic DIP
8 SO
HYST
DIP/SO/µMAX
8 µMAX
8 Plastic DIP
8 SO
1
2
3
4
8
7
6
5
OUTA
V-
OUTB
V+
16 Plastic DIP
16 Narrow SO
16 Plastic DIP
16 Narrow SO
1-MAX934
MAX932
REF
INA+
INB+
HYST
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.
DIP/SO/µMAX
1
2
3
4
8
7
6
5
OUTA
V-
OUTB
V+
MAX933
REF
INA+
INB-
HYST
DIP/SO/µMAX
OUTB
OUTA
V+
OUTC
OUTD
GND
IND+
IND-
INC+
INC-
V-
1
16
15
14
13
12
11
10
9
2
3
4
5
6
7
8
INA-
MAX934
INA+
INB-
INB+
REF
DIP/Narrow SO
14 ______________________________________________________________________________________
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
1-MAX934
________________________________________________________P a c k a g e In fo rm a t io n
______________________________________________________________________________________ 15
Ult ra Lo w -P o w e r, Lo w -Co s t
Co m p a ra t o rs w it h 2 % Re fe re n c e
__________________________________________P a c k a g e In fo rm a t io n (c o n t in u e d )
1-MAX934
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
16 __________________Ma x im In t e g ra t e d P ro d u c t s , 1 2 0 S a n Ga b rie l Drive , S u n n yva le , CA 9 4 0 8 6 (4 0 8 ) 7 3 7 -7 6 0 0
© 1997 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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