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PDF MAX954 Data sheet ( Hoja de datos )
| Número de pieza | MAX954 | |
| Descripción | Ultra-Low-Power / Single-Supply Op Amp Comparator Reference | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-0431; Rev 1; 7/97
Ultra-Low-Power, Single-Supply
Op Amp + Comparator + Reference
_______________General Description
The MAX951–MAX954 feature combinations of a
micropower operational amplifier, comparator, and ref-
erence in an 8-pin package. In the MAX951 and
MAX952, the comparator’s inverting input is connected
to an internal 1.2V ±2% bandgap reference. 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.
The op amps in the MAX951/MAX953 are internally
compensated to be unity-gain stable, 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.
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.
____________________Selection Table
PART
INTERNAL
2%
PRECISION
REFERENCE
OP-AMP
GAIN
STABILITY
(V/V)
SUPPLY
COMPARATOR CURRENT
(µA)
MAX951
Yes
1
Yes 7
MAX952
Yes
10
Yes
7
MAX953
No
1 Yes 5
MAX954
No
10
Yes
5
____________________________Features
o Op Amp + Comparator + Reference in an 8-Pin
µMAX Package (MAX951/MAX952)
o 7µA Typical Supply Current
(Op Amp + Comparator + Reference)
o Comparator and Op-Amp Input Range Includes
Ground
o Outputs Swing Rail to Rail
o +2.4V to +7V Supply Voltage Range
o Unity-Gain Stable and 125kHz Decompensated
AV ≥ 10V/V Op-Amp Options
o Internal 1.2V ±2% Bandgap Reference
o Internal Comparator Hysteresis
o Op Amp Capable of Driving up to 1000pF Load
________________________Applications
Instruments, Terminals, and Bar-Code Readers
Battery-Powered Systems
Automotive Keyless Entry
Low-Frequency, Local-Area Alarms/Detectors
Photodiode Preamps
Smart Cards
Infrared Receivers for Remote Controls
Smoke Detectors and Safety Sensors
__________________Pin Configuration
TOP VIEW
AMPOUT
AMPIN-
AMPIN+
VSS
1
2
3
4
MAX951
MAX952
MAX953
MAX954
8 VDD
7 COMPOUT
6 REF (COMPIN-)
5 COMPIN+
DIP/SO/µMAX
Typical Operating Circuit and Ordering Information
appear at end of data sheet.
( ) ARE FOR MAX953/MAX954
________________________________________________________________ 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.
1 page  
Ultra-Low-Power, Single-Supply
Op Amp + Comparator + Reference
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
9
8
7
6 MAX951/MAX952
5
4 MAX953/MAX954
3
2
VCM OPAMP = 0V
AMPOUT = (VDD + VSS)/2
1 COMP- = 1.2V or REF
COMP+ = 1.1V
0
2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
SUPPLY VOLTAGE (V)
SUPPLY CURRENT
vs. TEMPERATURE
10
9
8
7
MAX951/MAX952
6
5
4 MAX953/MAX954
3
2
VDD = 2.8V (MAX951/2), VDD = 2.4V
(MAX953/4), VSS = 0V, VCM OPAMP = 0V
1 AMPOUT = 1/2 VDD, COMP- = 1.2V or REF
COMP+ = 1.1V
0
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
REFERENCE OUTPUT VOLTAGE
vs. LOAD CURRENT
1.30
1.28 VSUPPLY = 5V
1.26
SINKING CURRENT
1.24
1.22
1.20
1.18
1.16
SOURCING CURRENT
1.14
1.12
1.10
1
10
LOAD CURRENT (µA)
100
DC OPEN-LOOP GAIN vs. TEMPERATURE
1x106
POWER-SUPPLY REJECTION
RATIO vs. FREQUENCY
80
VDD = 2.0 to 3.0V, VSS = -2.5V
70 NONINVERTING
AMPIN+ = 0V
60 ACL = 1V/V (MAX951/2)
ACL = 10V/V (MAX953/4),
50 COMP- = 1.2V or REF
COMP+ = 1.1V from VSS
40 A
30 C
20 B
A: MAX951/952 REF
10 B: MAX951/953 OP AMP
C: MAX952/954 OP AMP
0
1x100 1x101 1x102 1x103 1x104 1x105 1x106
FREQUENCY (Hz)
MAX951/MAX953 OPEN-LOOP GAIN
AND PHASE vs. FREQUENCY
100 0
1x105
1x104
1x103
80
60
GAIN
40
PHASE
-60
-120
-180
1x102
1x101
VDD = 5V
1mHz INPUT SIGNAL
1x100 RL = 100kΩ
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
20 -240
0
RL = 100kΩ
-20
1
10 100 1k 10k
FREQUENCY (Hz)
-300
-360
100k 1M
REFERENCE VOLTAGE vs. TEMPERATURE
1.220
1.215
1.210
1.205
1.200
1.195
1.190
1.185
VDD = 5V
1.180
-60 -40 -20 0 20 40 60 80 100 120 140
TEMPERATURE (°C)
1x107
1x106
DC OPEN-LOOP GAIN vs.
SUPPLY VOLTAGE
1x105
1x104
1x103
1x102
1x101 1mHz INPUT SIGNAL
1x100 RL = 100kΩ
2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7
SUPPLY VOLTAGE (V)
MAX952/MAX954 OPEN-LOOP GAIN
AND PHASE vs. FREQUENCY
100 0
80 -60
60
PHASE
-120
40
-180
20 GAIN
-240
0
-20
RL = 100kΩ
-40
1
10 100 1k 10k
FREQUENCY (Hz)
-300
-360
100k 1M
_______________________________________________________________________________________ 5
5 Page 
Ultra-Low-Power, Single-Supply
Op Amp + Comparator + Reference
10kHz,
5Vp-p
NEC
SE307-C
51Ω
C2
15pF, 5%
NEC
PH302B
R2
1.0M,
1%
R1A
49.9k
1%
R1B
49.9k
1%
C1
150pF,
5%
AMP
MAX952
100k
0.1µF
LAYOUT-SENSITIVE AREA
1
R1 x C1 = R2 x C2 =
2π fC
Figure 5. Infrared Receiver Application
VCC = 5V
0.1µF
30k
10M
1.2V COMP
REF
Power-Supply Bypassing
Power-supply bypass capacitors are not required if the
supply impedance is low. For single-supply applications,
it is good general practice to bypass VDD with a. 0.1µF
capacitor to ground. Do not bypass the reference output.
________________Application Circuits
Low-Frequency Radio Receiver for
Alarms and Detectors
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 C1A, C1B, and C1C in a
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.
The layout and routing of components for the amplifier
should be tight to minimize 60Hz interference and
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.
Infrared Receiver Front End for
Remote Controls and Data Links
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-
RADIOACTIVE
IONIZATION
CHAMBER
SMOKE SENSOR
AMP
LAYOUT-SENSITIVE AREA
MAX953
VCC
4.7M
COMP
5.1M
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.
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
order to minimize the effect, a lowpass RC filter is
added to the connection from the reference to the non-
inverting input of the op amp.
Sensor Preamp and Alarm Trigger for
Smoke Detectors
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 battery drain without
resorting to complex sleep schemes, allowing continu-
ous monitoring and immediate detection.
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
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet MAX954.PDF ] | |
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