Rainbow Electronics MAX4040, MAX4044 User Manual

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________________General Description
The MAX4040–MAX4044 family of micropower op amps operates from a single +2.4V to +5.5V supply or dual ±1.2V to ±2.75V supplies and have Rail-to-Rail®input and output capabilities. These amplifiers provide a 90kHz gain-bandwidth product while using only 10µA of supply current per amplifier. The MAX4041/MAX4043 have a low-power shutdown mode that reduces supply current to less than 1µA and forces the output into a high-impedance state. The combination of low-voltage operation, rail-to-rail inputs and outputs, and ultra-low power consumption makes these devices ideal for any portable/battery-powered system.
These amplifiers have outputs that typically swing to within 10mV of the rails with a 100kload. Rail-to-rail input and output characteristics allow the full power­supply voltage to be used for signal range. The combi­nation of low input offset voltage, low input bias current, and high open-loop gain makes them suitable for low­power/low-voltage precision applications.
The MAX4040 is offered in a space-saving 5-pin SOT23 package. All specifications are guaranteed over the
-40°C to +85°C extended temperature range.
________________________Applications
Battery-Powered Strain Gauges Systems
Sensor Amplifiers
Portable/Battery-Powered Cellular Phones Electronic Equipment
Notebook Computers
Digital Scales PDAs
____________________________Features
Single-Supply Operation Down to +2.4VUltra-Low Power Consumption:
10µA Supply Current per Amplifier 1µA Shutdown Mode (MAX4041/MAX4043)
Rail-to-Rail Input Common-Mode RangeOutputs Swing Rail-to-RailNo Phase Reversal for Overdriven Inputs200µV Input Offset VoltageUnity-Gain Stable for Capacitive Loads up to 200pF90kHz Gain-Bandwidth ProductAvailable in Space-Saving 5-Pin SOT23 and
8-Pin µMAX Packages
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower Rail-to-Rail I/O Op Amps
________________________________________________________________
Maxim Integrated Products
1
V
EE
IN-IN+
15V
CC
OUT
MAX4040
SOT23-5
TOP VIEW
2
34
19-1377; Rev 0; 5/98
PART
MAX4040EUK-T
MAX4040EUA MAX4040ESA -40°C to +85°C
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE
PIN-
PACKAGE
5 SOT23-5 8 µMAX 8 SO
Ordering Information
Pin Configurations continued at end of data sheet.
NO. OF
AMPS
PIN-PACKAGE
MAX4040 1
5-pin SOT23, 8-pin µMAX/SO
PART
MAX4041 1 8-pin µMAX/SO
SHUTDOWN
Yes
MAX4044 4 14-pin SO
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.
MAX4042EUA MAX4042ESA -40°C to +85°C
-40°C to +85°C 8 µMAX 8 SO
MAX4044ESD
-40°C to +85°C 14 SO
SOT
TOP MARK
ACGF
— —
— —
Pin Configurations
Selector Guide
MAX4042 2 8-pin µMAX/SO
MAX4043 2
10-pin µMAX/ 14-pin SO
Yes
MAX4041ESA MAX4041EUA -40°C to +85°C
-40°C to +85°C 8 SO 8 µMAX
— —
MAX4043EUB MAX4043ESD -40°C to +85°C
-40°C to +85°C 10 µMAX 14 SO
— —
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS—T
A
= +25°C
(VCC= +5.0V, VEE= 0, VCM= 0, V
OUT
= VCC/ 2, SHDN = VCC, RL= 100ktied to VCC/ 2, unless otherwise noted.)
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.
Supply Voltage (VCCto VEE)..................................................+6V
All Other Pins ...................................(V
CC
+ 0.3V) to (VEE- 0.3V)
Output Short-Circuit Duration to V
CC
or VEE..............Continuous
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C).............571mW
8-Pin µMAX (derate 4.1mW/°C above +70°C)..............330mW
8-Pin SO (derate 5.88mW/°C above +70°C).................471mW
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
14-Pin SO (derate 8.33mW/°C above +70°C)..............667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
14 20VCC= 5.0V
VEE≤ VCM≤ V
CC
Input Offset Current I
OS
±0.5 ±3.0 nA
VEE≤ VCM≤ V
CC
V
IN+
- V
IN-
< 1.0V
Differential Input Resistance
R
IN(DIFF)
45 M
2.0 5.0
V
IN+
- V
IN-
> 2.5V
SHDN = VEE, MAX4041 and MAX4043 only
Large-Signal Voltage Gain
Shutdown Supply Current per Amplifier
I
CC(SHDN)
1.0
Supply-Voltage Range V
CC
2.4 5.5 VInferred from PSRR test
Output Voltage Swing High
4.4 k
V
OH
Inferred from the CMRR test
mV
A
VOL
dB
PARAMETER SYMBOL MIN TYP MAX UNITS
Supply Current per Amplifier
I
CC
10
µA
94
VCC= 2.4V
10
Specified as VCC- V
OH
Power-Supply Rejection Ratio
PSRR dB
(VEE+ 0.2V) V
OUT
(VCC- 0.2V)
60 90
74 85
Output Voltage Swing Low
Input Common-Mode Voltage Range
RL= 100k RL= 25k
RL= 100k RL= 25k
µA
V
CM
V
EE
V
CC
V
2.4V VCC≤ 5.5V 75 85
VCC= 2.4V
V
OL
mV
10
Specified as VEE- V
OL
Input Bias Current I
B
±2 ±10 nA
40 60
RL= 100k RL= 25k
Output Short-Circuit Current
I
OUT(SC)
mA
0.7Sourcing
2.5
Channel-to-Channel Isolation
Sinking
dB
CONDITIONS
80Specified at DC, MAX4042/MAX4043/MAX4044 only
VCC= 5.0V
±0.20 ±2.0
V
OS
Input Offset Voltage
mV
±0.25 ±2.5
VEE≤ VCM≤ V
CC
70 94
dBCMRR
Common-Mode Rejection Ratio
MAX404_EU_ All other packages
65 94
VEE≤ VCM≤ V
CC
MAX4044ESD MAX404_EU_ All other packages mV±0.20 ±1.50
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS—TA= +25°C (continued)
(VCC= +5.0V, VEE= 0, VCM= 0, V
OUT
= VCC/ 2, SHDN = VCC, RL= 100ktied to VCC/ 2, unless otherwise noted.)
MAX4040–MAX4044
PARAMETER SYMBOL MIN TYP MAX UNITSCONDITIONS
Supply Current per Amplifier
I
CC
28
Supply-Voltage Range V
CC
2.4 5.5 VInferred from PSRR test
VEE≤ VCM≤ V
CC
Input Offset Current I
OS
±8 nA
Input Voltage Noise Density e
n
70
nV/Hz
Input Current Noise Density i
n
0.05
pA/Hz Capacitive-Load Stability 200 pF Power-Up Time t
ON
200 µs
Input Capacitance C
IN
3 pF
f = 1kHz f = 1kHz A
VCL
= +1V/V, no sustained oscillations
Slew Rate SR 40 V/ms
Total Harmonic Distortion THD 0.05 % Settling Time to 0.01% t
S
50 µs
fIN= 1kHz, V
OUT
= 2Vp-p, AV= +1V/V
AV= +1V/V, V
OUT
= 2V
STEP
PARAMETER SYMBOL MIN TYP MAX UNITSCONDITIONS
Gain Margin G
m
18 dB
Output Leakage Current in Shutdown
I
OUT(SHDN)
20 100 nA
SHDN = VEE= 0, MAX4041/MAX4043 only (Note 1)
µA
6.0
SHDN = VEE, MAX4041 and MAX4043 only
Shutdown Supply Current per Amplifier
I
CC(SHDN)
µA
Shutdown Time t
SHDN
50 µsMAX4041 and MAX4043 only
Enable Time from Shutdown t
EN
150 µsMAX4041 and MAX4043 only
ELECTRICAL CHARACTERISTICS—TA= T
MIN
to
T
MAX
(VCC= +5.0V, VEE= 0, VCM= 0, V
OUT
= VCC/ 2, SHDN = VCC, RL= 100ktied to VCC/ 2, unless otherwise noted.) (Note 2)
Input Offset Voltage Drift TC
VOS
2 µV/°C
VEE≤ VCM≤ V
CC
Input Bias Current I
B
±20 nA
Phase Margin
Φ
m
68 degrees
±4.5
SHDN Logic Low
V
IL
0.3 x V
CC
VMAX4041/MAX4043 only
SHDN Logic High
V
IH
0.7 x V
CC
VMAX4041/MAX4043 only
SHDN Input Bias Current
IIH, I
IL
40 120 nAMAX4041/MAX4043 only
Gain Bandwidth Product GBW 90 kHz
±5.0V
OS
Input Offset Voltage mV
±3.5
VEE≤ VCM≤ V
CC
MAX4044ESA
All other packages
MAX404_EU_
20
0
-60 -40 -20 20
40
100
SUPPLY CURRENT PER AMPLIFIER
vs. TEMPERATURE
6 4 2
16 14
18
MAX4040/44-01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
0 60
10
8
12
80
VCC = +5.5V
VCC = +2.4V
5
0
-60 -40 -20
0
20 40 100
MAX4041/MAX4043
SHUTDOWN SUPPLY CURRENT
PER AMPLIFIER vs. TEMPERATURE
1
4
MAX4040/44-01.5
TEMPERATURE (°C)
SHUTDOWN SUPPLY CURRENT (µA)
60
2
3
80
VCC = +5.5V
SHDN = 0
VCC = +2.4V
__________________________________________Typical Operating Characteristics
(VCC= +5.0V, VEE= 0, VCM= V
CC
/ 2, SHDN = VCC, RL= 100kto V
CC
/ 2, TA= +25°C, unless otherwise noted.)
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
4 _______________________________________________________________________________________
Large-Signal Voltage Gain
Output Voltage Swing High
V
OH
Inferred from the CMRR test
mV
A
VOL
dB
PARAMETER SYMBOL MIN TYP MAX UNITS
Specified as VCC- V
OH
, R
L
= 25k
Common-Mode Rejection Ratio
CMRR dB
(VEE+ 0.2V) V
OUT
(VCC- 0.2V), RL= 25k
125
68
Output Voltage Swing Low
Input Common-Mode Voltage Range
V
CM
V
EE
V
CC
V
60
V
OL
mV
Specified as VEE- V
OL
, R
L
= 25k
75
CONDITIONS
ELECTRICAL CHARACTERISTICS—TA= T
MIN
to
T
MAX
(continued)
(VCC= +5.0V, VEE= 0, VCM= 0, V
OUT
= VCC/ 2, SHDN = VCC, RL= 100ktied to VCC/ 2, unless otherwise noted.) (Note 2)
Note 1: Tested for V
EE
V
OUT
VCC. Does not include current through external feedback network.
Note 2: All devices are 100% tested at T
A
= +25°C. All temperature limits are guaranteed by design.
Power-Supply Rejection Ratio
PSRR dB2.4V VCC≤ 5.5V 70
MAX404_EU_
VEE≤ VCM≤ V
CC
All other packages 65
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
_______________________________________________________________________________________ 5
120
0
-60 -40 -20 20
40
100
OUTPUT SWING HIGH
vs. TEMPERATURE
20
100
80
MAX4040/44-07
TEMPERATURE (°C)
VOLTAGE FROM V
CC
(mV)
0 60
60
40
80
VCC = +2.4V, RL = 10k
RL TO V
EE
VCC = +5.5V, RL = 20k
VCC = +5.5V, RL = 100k
VCC = +2.4V, RL = 100k
120
0
-60 -40 -20 20
40
100
OUTPUT SWING LOW
vs. TEMPERATURE
20
100
80
MAX4040/44-08
TEMPERATURE (°C)
VOLTAGE FROM V
EE
(mV)
0 60
60
40
80
VCC = +2.4V, RL = 10k
VCC = +5.5V, RL = 20k
VCC = +5.5V, RL = 100k
VCC = +2.4V, RL = 100k
RL TO V
CC
-80
-100
-60 -40 -20 20
40
100
COMMON-MODE REJECTION
vs. TEMPERATURE
-95
-85
MAX4040/44-09
TEMPERATURE (°C)
COMMON-MODE REJECTION (dB)
0 60
-90
80
VCC = +2.4V
VCC = +5.5V
0
-4
-60 -40 -20 20
40
100
INPUT BIAS CURRENT
vs. TEMPERATURE
-3
-1
MAX4040/44-04
TEMPERATURE (°C)
INPUT BIAS CURRENT (nA)
0 60-280
VCM = 0
VCC = +2.4V
VCC = +5.5V
5.0
-5.0 0 0.2
0.6 1.0 1.4
INPUT BIAS CURRENT vs.
COMMON-MODE VOLTAGE (V
CC
= 2.4V)
-2.5
2.5
MAX4040/44-5
VCM (V)
I
BIAS
(nA)
0
1.8
2.2
V
CC
= +2.4V
5.0
-5.0 0 0.5
1.5
2.5 3.5
4.5
INPUT BIAS CURRENT vs.
COMMON-MODE VOLTAGE (V
CC
= 5.5V)
-2.5
2.5
MAX4040/44-06
VCM (V)
I
BIAS
(nA)
0
5.5
V
CC
= +5.5V
400
0
-60 -40 -20 20
40
100
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
100
300
MAX4040/44-03
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (µV)
0 60
200
80
Typical Operating Characteristics (continued)
(VCC= +5.0V, VEE= 0, VCM= V
CC
/ 2, SHDN = VCC, RL= 100kto V
CC
/ 2, TA= +25°C, unless otherwise noted.)
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
6 _______________________________________________________________________________________
100
30
0 100 300 500
OPEN-LOOP GAIN vs. OUTPUT SWING LOW
(V
CC
= +2.4V, RL TIED TO VCC)
50
40
90
80
MAX4040/44-10
V
OUT
(mV)
GAIN (dB)
200 400
70 60
RL = 100k
RL = 10k
100
110
0 100 200 300 400
OPEN-LOOP GAIN vs. OUTPUT SWING HIGH
(V
CC
= +5.5V, RL TIED TO VEE)
50
40
90
80
MAX4040/44-13
V
OUT
(mV)
GAIN (dB)
70 60
RL = 20k
RL = 100k
100
30
0 100 300 500
OPEN-LOOP GAIN vs. OUTPUT SWING HIGH
(V
CC
= +2.4V, RL TIED TO VEE)
50
40
90
80
MAX4040/44-11
V
OUT
(mV)
GAIN (dB)
200 400
70 60
RL = 100k
RL = 10k
100
110
0 100 200 300 400
OPEN-LOOP GAIN vs. OUTPUT SWING LOW
(V
CC
= +5.5V, RL TIED TO VCC)
50
40
90
80
MAX4040/44-12
V
OUT
(mV)
GAIN (dB)
70 60
RL = 100k
RL = 20k
110
70
-60 -40 -20 20
40
100
OPEN-LOOP GAIN
vs. TEMPERATURE
75
80
105 100
95
MAX4040/44-14
TEMPERATURE (°C)
GAIN (dB)
0 60
90 85
80
VCC = +5.5V, RL = 20kTO V
CC
VCC = +5.5V, RL = 20kTO V
EE
VCC = +2.4V, RL = 10kTO V
EE
VCC = +2.4V, RL = 10kTO V
CC
110
70
-60 -40 -20 20
40
100
OPEN-LOOP GAIN
vs. TEMPERATURE
75
80
105 100
95
MAX4040/44-15
TEMPERATURE (°C)
GAIN (dB)
0 60
90 85
80
VCC = +5.5V, RL TO V
CC
VCC = +5.5V, RL TO V
EE
VCC = +2.4V, RL TO V
CC
VCC = +2.4V, RL TO V
EE
____________________________________Typical Operating Characteristics (continued)
(VCC= +5.0V, VEE= 0, VCM= V
CC
/ 2, SHDN = VCC, RL= 100kto V
CC
/ 2, TA= +25°C, unless otherwise noted.)
60
-40 10 100 1k 10k 100k
GAIN AND PHASE vs. FREQUENCY
(NO LOAD)
-20
-30
MAX4040/44-16
FREQUENCY (Hz)
GAIN (dB)
0
-10
20
10
30
40
50
180
-180
-108
-144
PHASE (DEGREES)
-36
-72
36 0
72
108
144
AV = +1000V/V
60
-40 10 100 1k 10k 100k
GAIN AND PHASE vs. FREQUENCY
(C
L
= 100pF)
-20
-30
MAX4040/44-17
FREQUENCY (Hz)
GAIN (dB)
0
-10
20 10
30
40
50
180
-180
-108
-144
PHASE (DEGREES)
-36
-72
36 0
72
108
144
AV = +1000V/V
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
_______________________________________________________________________________________
7
____________________________________Typical Operating Characteristics (continued)
(VCC= +5.0V, VEE= 0, VCM= V
CC
/ 2, SHDN = VCC, RL= 100kto V
CC
/ 2, TA= +25°C, unless otherwise noted.)
1
0.01 1 100010010
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
0.1
MAX4040/44-19
FREQUENCY (Hz)
THD + NOISE (%)
RL = 10k
RL = 100k
1000
10
0 250 500 1000
LOAD RESISTOR vs.
CAPACITIVE LOAD
MAX4040/44-20
C
LOAD
(pF)
R
LOAD
(k)
750
100
10%
OVERSHOOT
REGION OF
MARGINAL STABILITY
REGION OF
STABLE OPERATION
10µs/div
SMALL-SIGNAL TRANSIENT RESPONSE
(NONINVERTING)
MAX4040/44-21
50mV/div
100mV
100mV
IN
OUT
0V
0V
10µs/div
SMALL-SIGNAL TRANSIENT RESPONSE
(INVERTING)
MAX4040/44-22
50mV/div
100mV
100mV
IN
OUT
0V
0V
100µs/div
LARGE-SIGNAL TRANSIENT RESPONSE
(NONINVERTING)
MAX4040/42/44-23
2V/div
4.5V
0.5V
4.5V
IN
0.5V
OUT
100µs/div
LARGE-SIGNAL TRANSIENT RESPONSE
(INVERTING)
MAX4040/42/44-24
2V/div
+2V
-2V
-2V
+2V
IN
OUT
-60
-110 10 1k 10k
100
MAX4042/MAX4043/MAX4044
CROSSTALK vs. FREQUENCY
-100
MAX4040/44-18
FREQUENCY (Hz)
GAIN (dB)
-90
-80
-70
RL = 10k
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
8 _______________________________________________________________________________________
_______________Detailed Description
Rail-to-Rail Input Stage
The MAX4040–MAX4044 have rail-to-rail inputs and rail-to-rail output stages that are specifically designed for low-voltage, single-supply operation. The input stage consists of separate NPN and PNP differential stages, which operate together to provide a common­mode range extending to both supply rails. The crossover region of these two pairs occurs halfway between VCCand VEE. The input offset voltage is typi­cally 200µV. Low operating supply voltage, low supply current, rail-to-rail common-mode input range, and rail­to-rail outputs make this family of operational amplifiers
an excellent choice for precision or general-purpose, low-voltage battery-powered systems.
Since the input stage consists of NPN and PNP pairs, the input bias current changes polarity as the common­mode voltage passes through the crossover region. Match the effective impedance seen by each input to reduce the offset error caused by input bias currents flowing through external source impedances (Figures 1a and 1b). The combination of high source impedance plus input capacitance (amplifier input capacitance plus stray capacitance) creates a parasitic pole that produces an underdamped signal response. Reducing input capacitance or placing a small capacitor across the feedback resistor improves response in this case.
______________________________________________________________Pin Description
1
2 44 4 11
Negative Supply. Tie to ground for single-supply operation.
V
EE
3
Amplifier Output. High impedance when in shutdown mode.
OUT
4 Inverting InputIN-
Noninverting InputIN+
5 108 14 4
5, 7,
8, 10
No Connection. Not internally con­nected.
N.C.
Positive SupplyV
CC
1, 91, 7 1, 13 1, 7
Outputs for Amplifiers A and B. High impedance when in shutdown mode.
OUTA,
OUTB
Shutdown Input. Drive high, or tie to VCCfor normal operation. Drive to V
EE
to place device in shutdown mode.
SHDN
2, 82, 6 2, 12 2, 6
3, 73, 5 3, 11 3, 5
Noninverting Inputs to Amplifiers A and B
INA+,
INB+
5, 6
Inverting Inputs to Amplifiers A and B
INA-,
INB-
6, 9
8, 14 Outputs for Amplifiers C and D
OUTC,
OUTD
Shutdown Inputs for Amplifiers A and B. Drive high, or tie to V
CC
for normal operation. Drive to VEEto place device in shutdown mode.
SHDNA,
SHDNB
9, 13
10, 12
Noninverting Inputs to Amplifiers C and D
INC+,
IND+
Inverting Inputs to Amplifiers C and D
INC-,
IND-
6
4 3
2 7
1, 5
8
6
4 3
2 7
1, 5, 8
MAX4043
MAX4044
PIN
µMAX
MAX4042
SO
MAX4041
FUNCTIONNAME
SOT23-5
MAX4040
SO/µMAX
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
_______________________________________________________________________________________ 9
The MAX4040–MAX4044 family’s inputs are protected from large differential input voltages by internal 2.2k series resistors and back-to-back triple-diode stacks across the inputs (Figure 2). For differential input volt­ages (much less than 1.8V), input resistance is typically 45M. For differential input voltages greater than 1.8V, input resistance is around 4.4k, and the input bias current can be approximated by the following equation:
I
BIAS
= (V
DIFF
- 1.8V) / 4.4k
In the region where the differential input voltage approaches 1.8V, the input resistance decreases expo­nentially from 45Mto 4.4kas the diode block begins conducting. Conversely, the bias current increases with the same curve.
Rail-to-Rail Output Stage
The MAX4040–MAX4044 output stage can drive up to a 25kload and still swing to within 60mV of the rails. Figure 3 shows the output voltage swing of a MAX4040 configured as a unity-gain buffer, powered from a single +4.0V supply voltage. The output for this setup typically swings from (VEE+ 10mV) to (VCC- 10mV) with a 100k load.
Applications Information
Power-Supply Considerations
The MAX4040–MAX4044 operate from a single +2.4V to +5.5V supply (or dual ±1.2V to ±2.75V supplies) and consume only 10µA of supply current per amplifier. A high power-supply rejection ratio of 85dB allows the amplifiers to be powered directly off a decaying battery voltage, simplifying design and extending battery life.
Power-Up Settling Time
The MAX4040–MAX4044 typically require 200µs to power up after VCCis stable. During this start-up time, the output is indeterminant. The application circuit should allow for this initial delay.
R3
R3 = R1 R2
R1 R2
MAX4040– MAX4044
V
IN
Figure 1b. Minimizing Offset Error Due to Input Bias Current (Inverting)
2.2k
2.2k
IN-
IN+
Figure 2. Input Protection Circuit
R3
V
IN
R3 = R1 R2
R1 R2
MAX4040– MAX4044
Figure 1a. Minimizing Offset Error Due to Input Bias Current (Noninverting)
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
10 ______________________________________________________________________________________
Shutdown Mode
The MAX4041 (single) and MAX4043 (dual) feature a low-power shutdown mode. When the shutdown pin (SHDN) is pulled low, the supply current drops to 1µA per amplifier, the amplifier is disabled, and the outputs enter a high-impedance state. Pulling SHDN high or leaving it floating enables the amplifier. Take care to ensure that parasitic leakage current at the SHDN pin does not inadvertently place the part into shutdown mode when SHDN is left floating. Figure 4 shows the output voltage response to a shutdown pulse. The logic threshold for SHDN is always referred to V
CC
/ 2 (not to GND). When using dual supplies, pull SHDN to VEEto enter shutdown mode.
Load-Driving Capability
The MAX4040–MAX4044 are fully guaranteed over tem­perature and supply voltage to drive a maximum resis­tive load of 25kto VCC/ 2, although heavier loads can be driven in many applications. The rail-to-rail output stage of the amplifier can be modeled as a current source when driving the load toward VCC, and as a cur­rent sink when driving the load toward VEE. The magni­tude of this current source/sink varies with supply voltage, ambient temperature, and lot-to-lot variations of the units.
Figures 5a and 5b show the typical current source and sink capability of the MAX4040–MAX4044 family as a function of supply voltage and ambient temperature. The contours on the graph depict the output current value, based on driving the output voltage to within 50mV, 100mV, and 200mV of either power-supply rail.
1200
0
-60 -40 -20 100
200
400
1000
MAX4040-44 fig05a
TEMPERATURE (°C)
OUTPUT SOURCE CURRENT (µA)
0 4020
600
800
8060
VCC = 5.5V, VOH = 200mV
VCC = 5.5V, VOH = 100mV
VCC = 2.4V, VOH = 50mV
VCC = 5.5V, VOH = 50mV
VCC = 2.4V, V
OH
= 200mV
VCC = 2.4V, V
OH
= 100mV
Figure 5a. Output Source Current vs. Temperature
3000
0
-60 -40 -20 100
500
1000
2500
MAX4040-44 fig05b
TEMPERATURE (°C)
OUTPUT SINK CURRENT (µA)
0 4020
1500
2000
8060
VCC = 5.5V, VOL = 200mV
VCC = 2.4V, VOL = 200mV
VCC = 5.5V, V
OL
= 100mV
VCC = 2.4V, VOL = 50mV
VCC = 5.5V, VOL = 50mV
VCC = 2.4V, VOL = 100mV
Figure 5b. Output Sink Current vs. Temperature
1V/div
OUT
IN
1V/div
MAX4040-44 fig03
200µs/div
RL = 100k TIED TO V
EE
VIN = 4.0V f
IN
= 1kHz
Figure 3. Rail-to-Rail Input/Output Voltage Range
MAX4040-44 fig04
200µs/div
5V/div
1V/div
SHDN
OUT
VIN = 2V R
L
= 100k TIED TO V
EE
Figure 4. Shutdown Enable/Disable Output Voltage
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
______________________________________________________________________________________ 11
For example, a MAX4040 running from a single +2.4V supply, operating at TA= +25°C, can source 240µA to within 100mV of VCCand is capable of driving a 9.6k load resistor to VEE:
The same application can drive a 4.6kload resistor when terminated in VCC/ 2 (+1.2V in this case).
Driving Capacitive Loads
The MAX4040–MAX4044 are unity-gain stable for loads up to 200pF (see Load Resistor vs. Capacitive Load graph in
Typical Operating Characteristics
). Applications that require greater capacitive drive capa­bility should use an isolation resistor between the output and the capacitive load (Figures 6a–6c). Note that this alternative results in a loss of gain accuracy because R
ISO
forms a voltage divider with the load resistor.
Power-Supply Bypassing and Layout
The MAX4040–MAX4044 family operates from either a single +2.4V to +5.5V supply or dual ±1.2V to ±2.75V supplies. For single-supply operation, bypass the power supply with a 100nF capacitor to VEE(in this case GND). For dual-supply operation, both the V
CC
and VEEsupplies should be bypassed to ground with separate 100nF capacitors.
Good PC board layout techniques optimize perfor­mance by decreasing the amount of stray capacitance at the op amp’s inputs and output. To decrease stray capacitance, minimize trace lengths by placing exter­nal components as close as possible to the op amp. Surface-mount components are an excellent choice.
Using the MAX4040–MAX4044
as Comparators
Although optimized for use as operational amplifiers, the MAX4040–MAX4044 can also be used as rail-to-rail I/O comparators. Typical propagation delay depends on the input overdrive voltage, as shown in Figure 7. External hysteresis can be used to minimize the risk of output oscillation. The positive feedback circuit, shown in Figure 8, causes the input threshold to change when the output voltage changes state. The two thresholds create a hysteresis band that can be calculated by the following equations:
V
HYST
= VHI- V
LO
VLO= VINx R2 / (R1 + (R1 x R2 / R
HYST
) + R2)
VHI= [(R2 / R1 x VIN) + (R2 / R
HYST
) x VCC] /
(1 + R1 / R2 + R2 / R
HYST
)
R =
2.4V - 0.1V 240 A
9.6k to V
L EE
µ
=
50mV/div
IN
OUT
50mV/div
MAX4040/42/44 fig06b
100µs/div
R
ISO
= NONE, RL = 100k, CL = 700pF
Figure 6b. Pulse Response without Isolating Resistor
50mV/div
IN
OUT
50mV/div
MAX4040/42/44 fig06c
100µs/div
R
ISO
= 1k, RL = 100k, CL = 700pF
Figure 6c. Pulse Response with Isolating Resistor
R
ISO
C
L
R
L
MAX4040– MAX4044
AV =
R
L
1
R
L
+ R
ISO
Figure 6a. Using a Resistor to Isolate a Capacitive Load from the Op Amp
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
12 ______________________________________________________________________________________
The MAX4040–MAX4044 contain special circuitry to boost internal drive currents to the amplifier output stage. This maximizes the output voltage range over which the amplifiers are linear. In an open-loop com­parator application, the excursion of the output voltage is so close to the supply rails that the output stage tran­sistors will saturate, causing the quiescent current to increase from the normal 10µA. Typical quiescent cur­rents increase to 35µA for the output saturating at V
CC
and 28µA for the output at VEE.
Using the MAX4040–MAX4044
as Ultra-Low-Power Current Monitors
The MAX4040–MAX4044 are ideal for applications pow­ered from a battery stack. Figure 9 shows an application circuit in which the MAX4040 is used for monitoring the current of a battery stack. In this circuit, a current load is applied, and the voltage drop at the battery terminal is sensed.
The voltage on the load side of the battery stack is equal to the voltage at the emitter of Q1, due to the feedback loop containing the op amp. As the load cur­rent increases, the voltage drop across R1 and R2 increases. Thus, R2 provides a fraction of the load cur­rent (set by the ratio of R1 and R2) that flows into the emitter of the PNP transistor. Neglecting PNP base cur­rent, this current flows into R3, producing a ground-ref­erenced voltage proportional to the load current. Scale R1 to give a voltage drop large enough in comparison to VOSof the op amp, in order to minimize errors.
The output voltage of the application can be calculated using the following equation:
V
OUT
= [I
LOAD
x (R1 / R2)] x R3
For a 1V output and a current load of 50mA, the choice of resistors can be R1 = 2, R2 = 100k, R3 = 1M. The circuit consumes less power (but is more suscepti­ble to noise) with higher values of R1, R2, and R3.
R2
R1
V
IN
OUTPUT
INPUT
V
OH
V
OL
V
EE
V
CC
V
OUT
R
HYST
V
EE
MAX4040– MAX4044
HYSTERESIS
V
LO
V
OH
V
HI
Figure 8. Hysteresis Comparator Circuit
R1
I
LOAD
R2
V
CC
V
EE
R3
V
OUT
Q1
MAX4040
Figure 9. Current Monitor for a Battery Stack
10,000
10
0 20 3010 100
100
1000
MAX4040-44 fig07
V
OD
(mV)
t
PD
(µs)
40 50 60 70 80
90
tPD-; V
CC
= +5V
tPD+; V
CC
= +2.4V
tPD-; V
CC
= +2.4V
tPD+; V
CC
= +5V
Figure 7. Propagation Delay vs. Input Overdrive
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
______________________________________________________________________________________ 13
_____________________________________________Pin Configurations (continued)
OUT
N.C.V
EE
1 2
87N.C.
V
CC
IN-
IN+
N.C.
SO/µMAX
TOP VIEW
3
4
6
5
MAX4040
OUT
N.C.V
EE
1 2
87SHDN
VCCIN-
IN+
N.C.
SO/µMAX
3
4
6
5
MAX4041
INB-
INB+V
EE
1 2
87V
CC
OUTBINA-
INA+
OUTA
SO/µMAX
3
4
6
5
MAX4042
14 13 12 11 10
9 8
1 2 3 4 5 6 7
V
CC
OUTB INB­INB+V
EE
INA+
INA-
OUTA
MAX4043
N.C. SHDNB N.C.N.C.
SHDNA
N.C.
SO
14 13 12 11 10
9 8
1 2 3 4 5 6 7
OUTD IND­IND+ V
EE
V
CC
INA+
INA-
OUTA
MAX4044
INC+ INC­OUTCOUTB
INB-
INB+
SO
1 2 3 4 5
10
9 8 7 6
V
CC
OUTB INB­INB+V
EE
INA+
INA-
OUTA
MAX4043
µMAX
SHDNBSHDNA
MAX4040/MAX4041
TRANSISTOR COUNT: 234
MAX4042/MAX4043
TRANSISTOR COUNT: 466
MAX4044
TRANSISTOR COUNT: 932 SUBSTRATE CONNECTED TO V
EE
___________________Chip Information
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
14 ______________________________________________________________________________________
________________________________________________________Package Information
SOT5L.EPS
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23,
Micropower, Rail-to-Rail I/O Op Amps
______________________________________________________________________________________ 15
___________________________________________Package Information (continued)
8LUMAXD.EPS
MAX4040–MAX4044
Single/Dual/Quad, Low-Cost, SOT23, Micropower, Rail-to-Rail I/O Op Amps
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
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information (continued)
10LUMAXB.EPS
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