MAX953ESA+T [MAXIM]
Operational Amplifier, 1 Func, 4000uV Offset-Max, CMOS, PDSO8, SO-8;
| 型号： | MAX953ESA+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Operational Amplifier, 1 Func, 4000uV Offset-Max, CMOS, PDSO8, SO-8 比较器 运算放大器 |
| 文件： | 总12页 (文件大小：117K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0431; Rev 1; 7/97
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
1–MAX954
_______________Ge n e ra l De s c rip t io n
____________________________Fe a t u re s
The MAX951–MAX954 fe a ture c omb ina tions of a
micropower operational amplifier, comparator, and ref-
e re nc e in a n 8-p in p a c ka g e . In the MAX951 a nd
MAX952, the comparator’s inverting input is connected
to a n inte rna l 1.2V ± 2% b a nd g a p re fe re nc e . The
MAX953 and MAX954 are offered without an internal
reference. The MAX951/MAX952 operate from a single
+2.7V to +7V supply with a typical supply current of
7µA, while the MAX953/MAX954 operate from +2.4V to
+7V with a 5µA typical supply current. Both the op amp
and comparator feature a common-mode input voltage
range that extends from the negative supply rail to with-
in 1.6V of the positive rail, as well as output stages that
swing rail to rail.
♦ Op Amp + Comparator + Reference in an 8-Pin
µMAX Package (MAX951/MAX952)
♦ 7µA Typical Supply Current
(Op Amp + Comparator + Reference)
♦ Comparator and Op-Amp Input Range Includes
Ground
♦ Outputs Swing Rail to Rail
♦ +2.4V to +7V Supply Voltage Range
♦ Unity-Gain Stable and 125kHz Decompensated
A
≥ 10V/V Op-Amp Options
V
♦ Internal 1.2V ±2% Bandgap Reference
♦ Internal Comparator Hysteresis
The op amps in the MAX951/MAX953 are internally
c omp e ns a te d to b e unity-g a in s ta b le , while the op
amps in the MAX952/MAX954 feature 125kHz typical
bandwidth, 66V/ms slew rate, and stability for gains of
10V/V or greater. These op amps have a unique output
stage that enables them to operate with an ultra-low
supply current while maintaining linearity under loaded
conditions. In addition, they have been designed to
exhibit good DC characteristics over their entire operat-
ing temperature range, minimizing input referred errors.
♦ Op Amp Capable of Driving up to 1000pF Load
________________________Ap p lic a t io n s
Instruments, Terminals, and Bar-Code Readers
Battery-Powered Systems
Automotive Keyless Entry
Low-Frequency, Local-Area Alarms/Detectors
Photodiode Preamps
The comparator output stage of these devices continu-
ously sources as much as 40mA. The comparators
eliminate power-supply glitches that commonly occur
when changing logic states, minimizing parasitic feed-
back and making the devices easier to use. In addition,
they contain ±3mV internal hysteresis to ensure clean
output switching, even with slow-moving input signals.
Smart Cards
Infrared Receivers for Remote Controls
Smoke Detectors and Safety Sensors
__________________P in Co n fig u ra t io n
____________________S e le c t io n Ta b le
INTERNAL
2%
PRECISION STABILITY
OP-AMP
GAIN
SUPPLY
COMPARATOR CURRENT
(µA)
TOP VIEW
PART
REFERENCE
(V/V)
MAX951
MAX952
MAX953
MAX954
Yes
Yes
No
1
10
1
Yes
Yes
Yes
Yes
7
7
5
5
1
2
3
4
8
7
6
5
AMPOUT
AMPIN-
AMPIN+
V
DD
COMPOUT
MAX951
MAX952
MAX953
MAX954
REF (COMPIN-)
COMPIN+
No
10
V
SS
DIP/SO/µMAX
( ) ARE FOR MAX953/MAX954
Typical Operating Circuit and Ordering Information
appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V to V )....................................................9V
SO (derate 5.88mW/°C above +70°C).........................471mW
µMAX (derate 4.10mW/°C above +70°C) ....................330mW
CERDIP (derate 8.00mW/°C above +70°C).................640mW
Operating Temperature Ranges
DD
SS
Inputs
Current (AMPIN_, COMPIN_)..........................................20mA
Voltage (AMPIN_, COMPIN_).......(V + 0.3V) to (V - 0.3V)
DD
SS
Outputs
MAX95_E_A .....................................................-40°C to +85°C
MAX95_MJA ..................................................-55°C to +125°C
Maximum Junction Temperatures
MAX95_E_A .................................................................+150°C
MAX95_MJA.................................................................+175°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10sec) .............................+300°C
Current (AMPOUT, COMPOUT)......................................50mA
Current (REF) ..................................................................20mA
Voltage (AMPOUT,
COMPOUT, REF) ..............(V + 0.3V) to (V - 0.3V)
DD
SS
Short-Circuit Duration (REF, AMPOUT)..................Continuous
Short-Circuit Duration (COMPOUT, V to V ≤ 7V)......1min
DD
SS
Continuous Power Dissipation (T = +70°C)
A
Plastic DIP (derate 9.09mW/°C above +70°C) ............727mW
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–MAX954
ELECTRICAL CHARACTERISTICS
(V = 2.8V to 7V for MAX951/MAX952, V = 2.4V to 7V for MAX953/MAX954, V = 0V, V = 0V for the MAX953/MAX954,
CM COMP
DD
DD
SS
V
= 0V, AMPOUT = (V + V ) / 2, COMPOUT = low, T = T
to T , typical values are at T = +25°C, unless
MAX A
CM OPAMP
DD
SS
A
MIN
otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
= T
MIN
2.8
2.7
2.4
TYP
MAX
7.0
7.0
7.0
10
11
13
8
UNITS
T
A
to T
MAX
MIN
MAX951/MAX952
Supply Voltage Range
V
DD
T = -10°C to +85°C
A
V
MAX953/MAX954
= +25°C, MAX951/MAX952
T
A
7
5
MAX951E/MAX952E
MAX951M/MAX952M
Supply Current
(Note 1)
I
S
µA
T
A
= +25°C, MAX953/MAX954
MAX953E/MAX954E
MAX953M/MAX954M
9
11
COMPARATOR
T
= +25°C
1
3
4
A
MAX95_EPA/ESA
MAX95_EUA (µMAX)
MAX95_MJA
Input Offset Voltage
(Note 2)
V
OS
mV
14
6
T
= +25°C
4
17
A
MAX95_EUA (µMAX)
MAX95_EPA/ESA
MAX95_MJA
Trip Point
(Note 3)
mV
nA
5
7
T
= +25°C
0.003
0.003
0.050
5
A
Input Leakage Current
(Note 4)
MAX95_E
MAX95_M
40
Common-Mode Range
CMVR
CMRR
V
SS
V
DD
-1.6V
V
Common-Mode Rejection Ratio
V
SS
to (V - 1.6V), MAX953/MAX954
0.1
1
mV/V
DD
2
_______________________________________________________________________________________
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
1–MAX954
ELECTRICAL CHARACTERISTICS (continued)
(V = 2.8V to 7V for MAX951/MAX952, V = 2.4V to 7V for MAX953/MAX954, V = 0V, V = 0V for the MAX953/MAX954,
CM COMP
DD
DD
SS
V
= 0V, AMPOUT = (V + V ) / 2, COMPOUT = low, T = T
to T , typical values are at T = +25°C, unless
MAX A
CM OPAMP
DD
SS
A
MIN
otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MAX951/MAX952, V = 2.8V to 7V
MIN
TYP
MAX
UNITS
0.05
0.05
22
1
1
DD
Power-Supply Rejection Ratio
Response Time
PSRR
mV/V
MAX953/MAX954, V = 2.4V to 7V
DD
V
OD
= 10mV
C
= 100pF, T =
A
L
T
pd
µs
+25°C, V - V = 5V
DD
SS
V
OD
= 100mV
4
Output High Voltage
Output Low Voltage
REFERENCE
V
I
= 2mA
V
DD
- 0.4V
V
V
OH
SOURCE
V
OL
I
= 1.8mA
V + 0.4V
SS
SINK
MAX95_EPA/ESA
MAX95_EUA (µMAX)
MAX95_MJA
1.176
1.130
1.164
1.200
1.200
1.200
0.1
1.224
1.270
1.236
Reference Voltage
(Note 5)
V
REF
V
I
= ±20µA, T = +25°C
A
OUT
Load Regulation
I
= ±6µA, MAX95_E
= ±3µA, MAX95_M
1.5
1.5
%
OUT
I
OUT
Voltage Noise
e
0.1Hz to 10Hz
16
1
µVp-p
n
OP AMP
T
= +25°C
3
A
MAX95_EPA/ESA
MAX95_EUA (µMAX)
MAX95_MJA
4
Input Offset Voltage
Input Bias Current
V
mV
OS
5
5
T
A
= +25°C
0.003
0.003
0.003
1000
0.050
5
I
MAX95_E
MAX95_M
nA
B
40
T
= +25°C
100
50
10
40
25
5
A
Large-Signal Gain
(no load)
AMPOUT = 0.5V to
A
VOL
MAX95_E
MAX95_M
V/mV
V/mV
4.5V, V - V = 5V
DD
SS
T
A
= +25°C
150
Large-Signal Gain
AMPOUT = 0.5V to
4.5V, V - V = 5V
A
VOL
MAX95_E
MAX95_M
(100kΩ load to V
)
SS
DD
SS
A
= +1V/V, MAX951/MAX953, V - V = 5V
20
125
12.5
66
V
DD
SS
Gain Bandwidth
Slew Rate
GBW
SR
kHz
A = +10V/V, MAX952/MAX954, V - V = 5V
V
DD
SS
A
V
= +1V/V, MAX951/MAX953, V - V = 5V
DD SS
V/ms
A = +10V/V, MAX952/MAX954, V - V = 5V
V
DD
SS
Common-Mode Input Range
CMVR
CMRR
V
SS
V
DD
- 1.6
1
V
Common-Mode Rejection Ratio
V
= V to (V - 1.6V)
0.03
0.07
0.07
80
mV/V
CM OPAMP
SS
DD
V
DD
= 2.8V to 7V, MAX951/MAX952
= 2.4V to 7V, MAX953/MAX954
1.0
1.0
Power-Supply Rejection Ratio
Input Noise Voltage
PSRR
en
mV/V
V
DD
f = 1kHz
o
nV√Hz
f = 0.1Hz to 10Hz
o
1.2
µVp-p
_______________________________________________________________________________________
3
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
ELECTRICAL CHARACTERISTICS (continued)
(V = 2.8V to 7V for MAX951/MAX952, V = 2.4V to 7V for MAX953/MAX954, V = 0V, V = 0V for the MAX953/MAX954,
CM COMP
DD
DD
SS
V
= 0V, AMPOUT = (V + V ) / 2, COMPOUT = low, T = T
to T
, typical values are at T = +25°C, unless
CM OPAMP
otherwise noted.)
DD
SS
A
MIN
MAX A
PARAMETER
SYMBOL
CONDITIONS
= 100kΩ to V
MIN
V - 500mV
DD
TYP
MAX
UNITS
Output High Voltage
Output Low Voltage
V
OH
R
R
V
V
L
L
SS
V
OL
= 100kΩ to V
V + 50mV
SS
SS
T
A
= +25°C
70
T
= +25°C, V - V = 5V
300
60
820
A
DD
SS
Output Source Current
Output Sink Current
I
µA
SRC
MAX95_E
MAX95_M
40
T
A
= +25°C
70
T
A
= +25°C, V - V = 5V
200
50
570
µA
DD
SS
I
SNK
MAX95_E
MAX95_M
1–MAX954
30
Note 1: Supply current is tested with COMPIN+ = (REF - 100mV) for MAX951/MAX952, and COMPIN+ = 0V for MAX953/MAX954.
Note 2: Input Offset Voltage is defined as the center of the input-referred hysteresis. V = REF for MAX951/MAX952, and
CM COMP
V
= 0V for MAX953/MAX954.
CM COMP
Note 3: Trip Point is defined as the differential input voltage required to make the comparator output change. The difference
between upper and lower trip points is equal to the width of the input-referred hysteresis. V = REF for
CM COMP
MAX951/MAX952, and V
= 0V for MAX953/MAX954.
CM COMP
Note 4: For MAX951/MAX952, input leakage current is measured for COMPIN- at the reference voltage. For MAX953/MAX954, input
leakage current is measured for both COMPIN+ and COMPIN- at V
.
SS
Note 5: Reference voltage is measured with respect to V . Contact factory for availability of a 3% accurate reference voltage in the
SS
µMAX package.
4
_______________________________________________________________________________________
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
1–MAX954
__________________________________________Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(T = +25°C, unless otherwise noted.)
A
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. TEMPERATURE
REFERENCE VOLTAGE vs. TEMPERATURE
1.220
1.215
1.210
1.205
1.200
10
9
9
8
8
7
7
MAX951/MAX952
6
MAX951/MAX952
6
5
4
3
2
1
0
5
MAX953/MAX954
4
MAX953/MAX954
1.195
1.190
3
V
= 0V
DD
CM OPAMP
V
= 2.8V (MAX951/2), V = 2.4V
DD
DD
2
1
0
AMPOUT = (V + V )/2
COMP- = 1.2V or REF
COMP+ = 1.1V
SS
(MAX953/4), V = 0V, V
= 0V
SS
CM OPAMP
V
DD
= 5V
1.185
1.180
AMPOUT = 1/2 V , COMP- = 1.2V or REF
DD
COMP+ = 1.1V
-60 -40 -20
0
20 40 60 80 100 120 140
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
-60 -40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
DC OPEN-LOOP GAIN vs.
SUPPLY VOLTAGE
REFERENCE OUTPUT VOLTAGE
vs. LOAD CURRENT
POWER-SUPPLY REJECTION
RATIO vs. FREQUENCY
7
1x10
1.30
80
V
= 5V
V
DD
= 2.0 to 3.0V, V = -2.5V
SS
SUPPLY
1.28
1.26
1.24
1.22
1.20
1.18
6
NONINVERTING
AMPIN+ = 0V
1x10
70
60
A
A
CL
= 1V/V (MAX951/2)
= 10V/V (MAX953/4),
CL
SINKING CURRENT
5
1x10
COMP- = 1.2V or REF
COMP+ = 1.1V from V
50
40
4
1x10
SS
A
3
1x10
C
30
20
2
1.16
1.14
1.12
1.10
1x10
B
SOURCING CURRENT
A: MAX951/952 REF
10 B: MAX951/953 OP AMP
1
1x10
1mHz INPUT SIGNAL
R = 100kΩ
C: MAX952/954 OP AMP
0
L
0
1x10
2
2.5
3
3.5
4 4.5 5 5.5 6 6.5 7
1x100 1x101 1x102 1x103 1x104 1x105 1x106
FREQUENCY (Hz)
1
10
100
SUPPLY VOLTAGE (V)
LOAD CURRENT (µA)
MAX952/MAX954 OPEN-LOOP GAIN
AND PHASE vs. FREQUENCY
MAX951/MAX953 OPEN-LOOP GAIN
AND PHASE vs. FREQUENCY
DC OPEN-LOOP GAIN vs. TEMPERATURE
6
1x10
1x10
1x10
1x10
1x10
0
100
80
60
40
20
0
100
80
0
5
4
3
2
-60
-60
PHASE
PHASE
GAIN
-120
-180
-240
-300
60
40
20
0
-120
-180
-240
-300
GAIN
V
DD
= 5V
1
1x10
1x10
-20
1mHz INPUT SIGNAL
R = 100kΩ
R = 100kΩ
L
R = 100kΩ
L
L
0
-360
-40
-20
-360
-60 -40 -20
0
20 40 60 80 100 120 140
1
10
100
1k
10k 100k 1M
1
10
100
1k
10k 100k 1M
TEMPERATURE (°C)
FREQUENCY (Hz)
FREQUENCY (Hz)
_______________________________________________________________________________________
5
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + 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 )
(T = +25°C, unless otherwise noted.)
A
OP-AMP SHORT-CIRCUIT CURRENT
vs. SUPPLY VOLTAGE
OP-AMP OUTPUT VOLTAGE
vs. LOAD CURRENT
2000
1500
1000
500
0.10
0.08
NONINVERTING
A, D: V
= ±1.5V
= ±2.5V
= ±3.5V
SUPPLY
AMPIN+ =(V - V )/2
DD
SS
B, E: V
SUPPLY
C
B
A
C, F: V
0.06
SUPPLY
0.04
SINKING CURRENT
0.02
SHORT TO V
SS
0.10
-0.02
-0.04
-0.06
-0.08
-0.10
SOURCING CURRENT
0
SHORT TO V
E
F
D
DD
-500
NONINVERTING
AMPIN+ = GND
1–MAX954
-1000
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
1
10
100
1000 2000
SUPPLY VOLTAGE (V)
LOAD CURRENT (µA)
OP AMP PERCENT OVERSHOOT
vs. CAPACITIVE LOAD
COMPARATOR OUTPUT VOLTAGE
vs. LOAD CURRENT
100
90
80
70
60
50
40
30
20
10
0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
PARTS
V
SUPPLY
SOURCING CURRENT
A: MAX951/2 3V
B: MAX951/3 5V
D: MAX952/4 3V
E: MAX952/4 5V
F
B
MAX951/3 A = 1V/V
MAX952/4 A = 10V/V
C
E
AMPOUT = 1V
D
PP
V
= (V - V /2)
DD SS
CM
A
V
= 5V
SUPPLY
SINKING CURRENT
1
2
4
5
6
3
10
10
10
10
10
10
0.01
0.1
1
10
100 200
CAPACITIVE LOAD (pF)
LOAD CURRENT (mA)
COMPARATOR SHORT-CIRCUIT
CURRENT vs. SUPPLY VOLTAGE
250
200
150
100
SOURCING CURRENT
50
0
SINKING CURRENT
-50
2
2.5
3
3.5
4 4.5 5 5.5 6 6.5 7
SUPPLY VOLTAGE (V)
6
_______________________________________________________________________________________
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
1–MAX954
____________________________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 )
(T = +25°C, unless otherwise noted.)
A
COMPARATOR RESPONSE TIME
COMPARATOR RESPONSE TIME
FOR VARIOUS INPUT OVERDRIVES (FALLING)
FOR VARIOUS INPUT OVERDRIVES (RISING)
0V
100mV
100mV
50mV
10mV
50mV
20mV
0V
0V
20mV
10mV
0V
2µs/div
MAX953, LOAD = 100kΩ || 100pF, V
2µs/div
MAX953, LOAD = 100kΩ || 100pF, V
= 5V
= 5V
SUPPLY
SUPPLY
MAX951/MAX953 OP-AMP
MAX951/MAX953 OP-AMP
LARGE-SIGNAL TRANSIENT RESPONSE
SMALL-SIGNAL TRANSIENT RESPONSE
2.5V
2.5V
200µs/div
100µs/div
NONINVERTING, A = 1V/V, LOAD = 100kΩ || 100pF to V , V
= 5V
NONINVERTING, A = 1V/V, LOAD = 100kΩ || 100pF to V , V
= 5V
VCL
SS SUPPLY
VCL
SS SUPPLY
MAX952/MAX954 OP-AMP
MAX952/MAX954 OP-AMP
SMALL-SIGNAL TRANSIENT RESPONSE
LARGE-SIGNAL TRANSIENT RESPONSE
2.5V
2.5V
100µs/div
100µs/div
NONINVERTING, A = 10V/V, LOAD = 100kΩ || 100pF to V , V
= 5V
NONINVERTING, A = 10V/V, LOAD = 100kΩ || 100pF to V , V = 5V
SS SUPPLY
VCL
SS SUPPLY
VCL
_______________________________________________________________________________________
7
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
______________________________________________________________P in De s c rip t io n
PIN
NAME
FUNCTION
MAX951
MAX952
MAX953
MAX954
1
2
1
2
AMPOUT
AMPIN-
AMPIN+
Op-Amp Output
Inverting Op-Amp Input
Noninverting Op-Amp Input
Negative Supply or Ground
Noninverting Comparator Input
3
3
4
4
V
SS
5
5
COMPIN+
REF
6
—
6
1.200V Reference Output. Also connected to inverting comparator input.
—
7
COMPIN-
COMPOUT
Inverting Comparator Input
Comparator Output
Positive Supply
7
8
8
V
DD
1–MAX954
AMPOUT
OP AMP
V
8
7
DD
8
1
V
DD
AMPOUT
OP AMP
COMPOUT
MAX953
MAX954
1
2
3
AMPIN-
AMPIN+
COMPOUT
COMPIN-
7
6
x1
2
3
AMPIN-
AMPIN+
REF
6
5
1.20V
4
V
SS
COMP
COMP
4
COMPIN+
5
V
SS
COMPIN+
MAX951
MAX952
Figure 1. MAX951–MAX954 Functional Diagrams
hig h-imp e d a nc e d iffe re ntia l inp uts a nd a c ommon-
mode input voltage range that extends from the nega-
tive supply rail to within 1.6V of the positive rail. They
have a CMOS output stage that swings rail to rail and is
driven by a proprietary high gain stage, which enables
them to operate with an ultra-low supply current while
maintaining linearity under loaded conditions. Careful
design results in good DC characteristics over their
entire operating temperature range, minimizing input
referred errors.
_______________De t a ile d De s c rip t io n
The MAX951–MAX954 are combinations of a micropow-
er op amp, comparator, and reference in an 8-pin pack-
age, as shown in Figure 1. In the MAX951/MAX952, the
comparator’s negative input is connected to a 1.20V
±2% bandgap reference. All four devices are optimized
to operate from a single supply. Supply current is less
than 10µA (7µA typical) for the MAX951/MAX952 and
less than 8µA (5µA typical) for the MAX953/MAX954.
Op Am p
The op amps in the MAX951/MAX953 are internally
c omp e ns a te d to b e unity-g a in s ta b le , while the op
amps in the MAX952/MAX954 feature 125kHz typical
gain bandwidth, 66V/ms slew rate, and stability for
gains of 10V/V or greater. All these op amps feature
Co m p a ra t o r
The comparator in the MAX951–MAX954 has a high-
impedance differential input stage with a common-
mod e inp ut volta g e ra ng e tha t e xte nd s from the
negative supply rail to within 1.6V of the positive rail.
Their CMOS output stage swings rail to rail and can
8
_______________________________________________________________________________________
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
1–MAX954
R2
R2
RA
R1
V
S
V
IN
COMPOUT
COMPOUT
RB
REF
REF
Figure 2. External Hysteresis
continuously source as much as 40mA. The compara-
tors eliminate power-supply glitches that commonly
occur when changing logic states, minimizing parasitic
feedback and making them easier to use. In addition,
they include internal hysteresis (±3mV) to ensure clean
output switching, even with slow-moving input signals.
The inputs can be taken above and below the supply
ra ils up to 300mV without d a ma g e . Inp ut volta g e s
beyond this range can forward bias the ESD-protection
diodes and should be avoided.
Co m p a ra t o r Hys t e re s is
Hysteresis increases the comparator’s noise immunity
by increasing the upper threshold and decreasing the
lower threshold. The comparator in these devices con-
tain a ±3mV wide internal hysteresis band to ensure
clean output switching, even with slow-moving signals.
When necessary, hysteresis can be increased by using
external resistors to add positive feedback, as shown in
Fig ure 2. This c irc uit inc re a s e s hys te re s is a t the
e xp e ns e of more s up p ly c urre nt a nd a s lowe r
response. The design procedure is as follows:
The MAX951–MAX954 comparator outputs swing rail to
rail (from V
using a +5V ±10% supply.
to V ). TTL compatibility is assured by
DD
SS
1) Set R2. The leakage current in COMPIN+ is less
than 5nA (up to +85°C), so current through R2 can
be as little as 500nA and still maintain good accura-
cy. If R2 = 2.4MΩ, the current through R2 at the
The MAX951–MAX954 comparator continuously outputs
source currents as high as 40mA and sink currents of
ove r 5mA, while ke e p ing q uie s c e nt c urre nts in the
microampere range. The output can source 100mA (at
upper trip point is V
/ R2 or 500nA.
REF
2) Choose the width of the hysteresis band. In this
V
DD
= 5V) for short pulses, as long as the package’s
example choose V
= 50mV.
EHYST
maximum power dissipation is not exceeded. The out-
put stage does not generate crowbar switching currents
during transitions; this minimizes feedback through the
supplies and helps ensure stability without bypassing.
V
− 2V
[
]
EHYST
IHYST
R1 = R2
V
+ 2V
IHYST
DD
where the internal hysteresis is V
= 3mV.
IHYST
Re fe re n c e
The internal reference in the MAX951/MAX952 has an
3) Determine R1. If the supply voltage is 5V, then R1 =
output of 1.20V with respect to V . Its accuracy is ±2%
SS
24kΩ.
in the -40°C to +85°C temperature range. It is comprised
of a trimmed bandgap reference fed by a proportional-
to-absolute-temperature (PTAT) current source and
buffered by a micropower unity-gain amplifier. The REF
output is typically capable of sourcing and sinking 20µA.
Do not bypass the reference output. The reference is
stable for capacitive loads less than 100pF.
4) Check the hysteresis trip points. The upper trip point is
R1 + R2
(
)
V
V
=
+ V
REF IHYST
(
)
IN(H)
R2
or 1.22V in our example. The lower trip point is 50mV
less, or 1.17V in our example.
If a resistor divider is used for R1, the calculations
should be modified using a Thevenin equivalent
model.
__________Ap p lic a t io n s In fo rm a t io n
The micropower MAX951–MAX954 are designed to
extend battery life in portable instruments and add
func tiona lity in p owe r-limite d ind us tria l c ontrols .
Following are some practical considerations for circuit
design and layout.
5) Determine R :
A
_______________________________________________________________________________________
9
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
V
CC
= 5V
ANTENNA
0.1µF
AMPIN+
MAX952
AMP
0.1µF
AMPOUT
20k
10M
C1
390pF C1
A
B
C1
C
L1
330mH
330pF
20-60pF
1.0M
R2
COMP
100k
1.2V
5.1M
R1
1
REF
L1 x C1 =
2
(2π f )
C
2pF to 10pF
LAYOUT-SENSITIVE AREA,
METAL RFI SHIELDING ADVISED
Figure 3. Compensation for Feedback-Node Capacitance
Figure 4. Low-Frequency Radio Receiver Application
1–MAX954
Op -Am p S t a b ilit y a n d Bo a rd La yo u t
Co n s id e ra t io n s
V
SHYST
R
≈ R2
, for V
>> V
A
SHYST IHYST
V
DD
Unlike other industry-standard micropower CMOS op
amps, the op amps in the MAX951–MAX954 maintain
stability in their minimum gain configuration while driving
he a vy c a p a c itive loa d s , a s d e mons tra te d in the
MAX951/MAX953 Op -Amp Pe rc e nt Ove rs hoot vs .
Ca p a c itive Loa d g ra p h in the Typ ic a l Op e ra ting
Characteristics.
In the example, R is again 24kΩ.
A
6) Select the upper trip point V
. Our example is set
S(H)
at 4.75V.
7) Calculate R .
B
V
+ V
R2 R
A
(
) ( )(
+ V
)
REF
IHYST
Although this family is primarily designed for low-fre-
quency applications, good layout is extremely impor-
tant. Low-power, high-impedance circuits may increase
the effects of board leakage and stray capacitance. For
example, the combination of a 10MΩ resistance (from
leakage between traces on a contaminated, poorly
designed PC board) and a 1pF stray capacitance pro-
vides a pole at approximately 16kHz, which is near the
amplifier’s bandwidth. Board routing and layout should
minimize le a ka g e a nd s tra y c a p a c ita nc e . In s ome
cases, stray capacitance may be unavoidable and it
may be necessary to add a 2pF to 10pF capacitor
across the feedback resistor to compensate; select the
smallest capacitor value that ensures stability.
R
=
B
R2 V
−
V
R
)(
+ R2
(
)
(
)
S H
( )
REF
IHSYT
A
R
is 8.19kΩ, or approximately 8.2kΩ.
B
In p u t No is e Co n s id e ra t io n s
Because low power requirements often demand high-
impedance circuits, effects from radiated noise are more
significant. Thus, traces between the op-amp or com-
parator inputs and any resistor networks attached should
be kept as short as possible.
Cro s s t a lk
Reference
Internal crosstalk to the reference from the comparator
In p u t Ove rd rive
With 100mV overdrive, comparator propagation delay
is typically 6µs. The Typical Operating Characteristics
show propagation delay for various overdrive levels.
is package dependent. Typical values (V
= 5V) are
DD
45mV for the plastic DIP package and 32mV for the SO
package. Applications using the reference for the op
amp or external circuitry can eliminate this crosstalk by
using a simple RC lowpass filter, as shown in Figure 5.
Supply current can increase when the op amp in the
MAX951–MAX954 is overdriven to the negative supply rail.
For example, when connecting the op amp as a compara-
tor and applying a -100mV input overdrive, supply current
rises by around 15µA and 32µA for supply voltages of
2.8V and 7V, respectively.
Op Amp
Internal crosstalk to the op amp from the comparator is
package dependent, but not input referred. Typical val-
ues (V
= 5V) are 4mV for the plastic DIP package
DD
and 280µV for the SO package.
10 ______________________________________________________________________________________
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
1–MAX954
V
CC
= 5V
10kHz,
5Vp-p
C2
15pF, 5%
MAX953
NEC
PH302B
V
CC
R2
1.0M,
1%
NEC
SE307-C
0.1µF
4.7M
30k
10M
51Ω
RADIOACTIVE
IONIZATION
CHAMBER
R1
A
49.9k
1%
AMP
C1
150pF,
5%
R1
B
49.9k
1%
AMP
SMOKE SENSOR
COMP
COMP
100k
0.1µF
1.2V
MAX952
LAYOUT-SENSITIVE AREA
5.1M
REF
LAYOUT-SENSITIVE AREA
1
R1 x C1 = R2 x C2 =
2π f
C
Figure 5. Infrared Receiver Application
Figure 6. Sensor Preamp and Alarm Trigger Application
Friend bandpass filter to reduce disturbances from
noise and eliminate low-frequency interference from
sunlight, fluorescent lights, etc. This circuit is applica-
ble for TV remote controls and low-frequency data links
up to 20kbps. Carrier frequencies are limited to around
10kHz. 10kHz is used in the example circuit.
P o w e r-S u p p ly Byp a s s in g
Power-supply bypass capacitors are not required if the
supply impedance is low. For single-supply applications,
it is good general practice to bypass V with a. 0.1µF
DD
capacitor to ground. Do not bypass the reference output.
________________Ap p lic a t io n Circ u it s
Component layout and routing for the amplifier should
be tight to reduce stray capacitance, 60Hz interfer-
ence, and RFI from the comparator. Crosstalk from
comparator edges will distort the amplifier signal. In
ord e r to minimize the e ffe c t, a lowp a s s RC filte r is
added to the connection from the reference to the non-
inverting input of the op amp.
Lo w -Fre q u e n c y Ra d io Re c e ive r fo r
Ala rm s a n d De t e c t o rs
Figure 4’s circuit is useful as a front end for low-frequen-
cy RF alarms. The unshielded inductor (M7334-ND from
Digikey) is used with capacitors C1 , C1 , and C1 in a
A
B
C
resonant circuit to provide frequency selectivity. The op
amp from a MAX952 amplifies the signal received. The
comparator improves noise immunity, provides a signal
strength threshold, and translates the received signal
into a pulse train. Carrier frequencies are limited to
around 10kHz. 10kHz is used in the example in Figure 4.
S e n s o r P re a m p a n d Ala rm Trig g e r fo r
S m o k e De t e c t o rs
The high-impedance CMOS inputs of the MAX951–
MAX954 op amp are ideal for buffering high-imped -
ance sensors, such as smoke detector ionization cham-
bers, piezoelectric transducers, gas detectors, and pH
sensors. Input bias currents are typically less than 3pA
at room temperature. A 5µA typical quiescent current
for the MAX953 will minimize b a tte ry d ra in without
resorting to complex sleep schemes, allowing continu-
ous monitoring and immediate detection.
The layout and routing of components for the amplifier
s hould b e tig ht to minimize 60Hz inte rfe re nc e a nd
crosstalk from the comparator. Metal shielding is rec-
ommended to prevent RFI from the comparator or digi-
tal circuitry from exciting the receiving antenna. The
transmitting antenna can be long parallel wires spaced
about 7.2cm apart, with equal but opposite currents.
Radio waves from this antenna will be detectable when
the receiver is brought within close proximity, but can-
cel out at greater distances.
Ionization-type smoke detectors use a radioactive source,
such as Americium, to ionize smoke particles. A positive
voltage on a plate attached to the source repels the posi-
tive smoke ions and accelerates them toward an outer
electrode connected to ground. Some ions collect on an
intermediate plate. With careful design, the voltage on this
plate will stabilize at a little less than one-half the supply
voltage under normal conditions, but rise higher when
smoke increases the ion current. This voltage is buffered
In fra re d Re c e ive r Fro n t En d fo r
Re m o t e Co n t ro ls a n d Da t a Lin k s
The circuit in Figure 5 uses the MAX952 as a PIN pho-
todiode preamplifier and discriminator for an infrared
receiver. The op amp is configured as a Delyiannis-
______________________________________________________________________________________ 11
Ult ra -Lo w -P o w e r, S in g le -S u p p ly
Op Am p + Co m p a ra t o r + Re fe re n c e
by the high input impedance op amp of a MAX951
(Figure 6). The comparator and resistor voltage divider
set an alarm threshold to indicate a fire.
___________________Ch ip To p o g ra p h y
V
DD
Design and fabrication of the connection from the inter-
mediate plate of the ionization chamber to the nonin-
ve rting inp ut of the op a mp is c ritic a l, s inc e the
impedance of this node must be well above 50MΩ. This
connection must be as short and direct as possible to
prevent charge leakage and 60Hz interference. Where
possible, the grounded outer electrode or chassis of
the ionization chamber should shield this connection to
re d uc e 60Hz inte rfe re nc e . Pa y s p e c ia l a tte ntion to
board cleaning, to prevent leakage due to ionic com-
pounds such as chlorides, flux, and other contaminants
from the manufacturing process. Where applicable, a
coating of high-purity wax may be used to insulate this
connection and prevent leakage due to surface mois-
ture or an accumulation of dirt.
AMPOUT
AMPIN-
COMPOUT
0. 084"
(2. 134mm)
AMPIN+
REF(COMPIN-)
COMPIN+
V
SS
1–MAX954
0. 058"
(1. 473mm)
______________Ord e rin g In fo rm a t io n
(
) ARE FOR MAX953/MAX954
PART
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
Dice*
TRANSISTOR COUNT: 163
SUBSTRATE CONNECTED TO V
MAX951C/D
MAX951EPA
MAX951ESA
MAX951EUA
MAX951MJA
MAX952C/D
MAX952EPA
MAX952ESA
MAX952EUA
MAX952MJA
MAX953C/D
MAX953EPA
MAX953ESA
MAX953EUA
MAX953MJA
MAX954C/D
MAX954EPA
MAX954ESA
MAX954EUA
MAX954MJA
DD
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
8 Plastic DIP
8 SO
8 µMAX
8 CERDIP**
Dice*
__________Typ ic a l Op e ra t in g Circ u it
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
8 Plastic DIP
8 SO
8
V
CC
0.1µF
INPUT
8 µMAX
AMPIN+
3
8 CERDIP**
Dice*
MAX951
MAX952
2
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
8 Plastic DIP
8 SO
1
5
6
8 µMAX
1M
COMPOUT
7
R2
8 CERDIP**
Dice*
R1
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
8 Plastic DIP
8 SO
REF
1.20V
8 µMAX
4
V
SS
8 CERDIP**
* Dice are tested at T = +25°C, DC parameters only.
A
** Contact factory for availability and processing to MIL-STD-883.
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.
12 ____________________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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