MAX44284FAWT+ [MAXIM]
36V, Input Common-Mode, High-Precision, Low-Power Current-Sense Amplifier;
| 型号： | MAX44284FAWT+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 36V, Input Common-Mode, High-Precision, Low-Power Current-Sense Amplifier |
| 文件： | 总15页 (文件大小：1036K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
General Description
Benefits and Features
● Supports Use of Small Current-Sense Resistors to
Improve Power-Supply Conversion Efficiency and
Measurement Accuracy
The MAX44284 is a high-side, current-sense amplifier
that operates with a 1.7V to 5.5V single supply and is
optimized for very low power operation with only 21µA of
quiescent current.
• Input Bias Current of 80nA (max)
The MAX44284 offers precision accuracy specifications
• Very Low 2μV Input Offset Voltage (MAX44284F/H)
of 2μV V
and gain error of 0.05%. The device features
• Extremely Low 50nV/°C Input Offset Tempco
Coefficient
OS
an input common-mode voltage range from -0.1V to
+36V. This current-sense amplifier has a voltage output
and is offered in four different gain versions.
•
-0.1V to +36V Wide Input Common-Mode Range
•
Low 0.05% Gain Error
The MAX44284 is offered in small 6-bump, 0.4mm-pitch
WLP (1.3mm x 0.9mm) and 6-pin SOT23 packages and is
specified for operation over the -40°C to +125°C automotive
temperature range.
● Extends Battery Life
•
•
•
Low Supply Current of 21μA
1.7V to 5.5V Single Supply
Shutdown Input (Independent of V
)
DD
Applications
● Smartphones and Tablets
● Notebook Computers
● DC-DC Current Sensing in Power Management
● Portable-/Battery-Powered Systems
● Medical Pulse Oximeters and Infusion Pumps
● Base Stations
● Four Fixed Gain Options Simplify Design
• 50V/V – MAX44284F
• 100V/V – MAX44284H
• 200V/V – MAX44284W
• 500V/V – MAX44284E
Ordering Information appears at end of data sheet.
Typical Application Circuit
ILOAD
RSENSE
VBATT = UP TO 36V
RS+
RS-
LOAD
VDD = 3.3V
MAX44284
VDD = 3.3V
OUT
µC
ADC
19-6862; Rev 9; 5/19
MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Absolute Maximum Ratings
V
to GND ............................................................-0.3V to +6V
Operating Temperature Range......................... -40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range............................ -65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow).......................................+260°C
DD
RS+, RS- to GND..................................................-0.3V to +40V
RS+ to RS-..........................................................................±40V
OUT, SHDN to GND................................. -0.3V to (V
Continuous Input Current (any pin)..................................±20mA
+ 0.3V)
DD
Continuous Power Dissipation (T = +70°C)
A
WLP (derate 10.5mW/°C above +70°C)......................840mW
SOT23 (derate 4.3mW/°C above +70°C) .................347.8mW
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.
Package Information
6 SOT23
PACKAGE CODE
Outline Number
U6+1, U6+1A
21-0058
90-0175
Land Pattern Number
Thermal Resistance, Single-Layer Board:
Junction to Ambient - θ (C/W)
N/A
80
JA
Junction to Case - θ (C/W)
JC
Thermal Resistance, Multi-Layer Board
Junction to Ambient (θ ) (C/W)
115
80
JA
Junction to Case (θ ) (C/W)
JC
6 WLP
PACKAGE CODE
W60A1+1
Outline Number
21-0656
Land Pattern Number
Refer to Application Note 1891
Thermal Resistance, Multi-Layer Board
Junction to Ambient (θ ) (C/W)
95.15
N/A
JA
Junction to Case (θ ) (C/W)
JC
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board.
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Electrical Characteristics
(V
= 3.3V, V
= 12V, V
= V /2, V = (V
- V
- V )/Gain, V
= V , R = 10kΩ to GND, T = -40°C to +125°C,
DD
CM
SENSE
FS
FS
DD
OH
OL
SHDN
DD
L
A
unless otherwise noted. Typical values are at T = +25°C.) (Note 2)
A
PARAMETER
POWER SUPPLY
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage
V
Guaranteed by PSRR
1.7
5.5
0.8
V
DD
Shutdown Supply Current
I
0.3
21
μA
SHDN
T
= +25°C, R = ∞
31.2
41.5
A
L
Supply Current
I
μA
DD
-40°C ≤ T ≤ +125°C, R = ∞
A
L
Power-Supply Rejection
Ratio
PSRR
1.7V ≤ V
≤ 5.5V, V
= 1V
100
1.3
110
dB
DD
OUT
Shutdown Voltage Low
Shutdown Voltage High
DC CHARACTERISTICS
V
0.55
+36
V
V
IL
V
IH
Input Common-Mode Voltage
Range
V
Guaranteed by CMRR
-0.1V ≤ V ≤ +36V, V
-0.1
91.3
120
V
CM
= RS-
= RS-
140
145
CM
CM
Common-Mode Rejection
Ratio (Note 5)
CMRR
dB
+0.1V ≤ V
(Note 7)
≤ +36V, V
CM
CM
Input Bias Current
I
, I
2
2
80
50
nA
nA
RS+ RS-
Input Offset Current
I
OS
MAX44284F (T = +25°C)
±2
±10
A
MAX44284F
±28
±12
(-40°C ≤ T ≤+125°C)
A
MAX44284H (T = +25°C)
±2
A
MAX44284H
±28
(-40°C ≤ T ≤+125°C)
A
Input Offset Voltage (Note 3)
V
μV
OS
MAX44284W (T = +25°C)
A
±10
±20.5
±38
MAX44284W
(-40°C ≤ T ≤ +125°C)
A
MAX44284E (T = +25°C)
A
±15
50
±26
±40
MAX44284E
(-40°C ≤ T ≤ +125°C)
A
Input Offset Voltage
Temperature Drift
TCV
G
nV°C
V/V
OS
MAX44284F
MAX44284H
MAX44284W
MAX44284E
50
100
200
500
Gain
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Electrical Characteristics (continued)
(V
= 3.3V, V
= 12V, V
= V /2, V = (V
- V
- V )/Gain, V
= V , R = 10kΩ to GND, T = -40°C to +125°C,
DD
CM
SENSE
FS
FS
DD
OH
OL
SHDN
DD
L
A
unless otherwise noted. Typical values are at T = +25°C.) (Note 2)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX44284F (T = +25°C)
0.05
0.15
A
MAX44284F
0.20
0.15
0.26
0.15
0.35
(-40°C ≤T ≤+125°C)
A
MAX44284H (TA = +25°C)
0.05
0.05
0.05
MAX44284H
(-40°C ≤ T ≤ +125°C)
A
Gain Error (Note 4)
GE
%
MAX44284W (T = +25°C)
A
MAX44284W
(-40°C ≤ T ≤ +125°C)
A
MAX44284E (T = +25°C)
A
0.16
0.39
MAX44284E
(-40°C ≤ T ≤ +125°C)
A
V
= V
- V
OUT
,
OH
DD
25
35
R = 10kΩ to GND
L
Output Voltage High
V
mV
mV
OH
I
= 100μA
20
1
SOURCE
No load
= 100µA
0.3
Output Voltage Low
V
OL
I
20
SINK
Input Differential Impedance
Output Impedance
6
MΩ
mΩ
200
AC CHARACTERISTICS
MAX44284F
MAX44284H
MAX44284W
MAX44284E
f = 1kHz
3
1.8
1
Small-Signal Bandwidth
BW
e
kHz
3dB
0.4
150
Input Voltage-Noise Density
nV/√Hz
n
AC Common-Mode Rejection
Ratio
f = 10kHz, 600mV
waveform
sinusoidal
P-P
AC CMRR
80
dB
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Electrical Characteristics (continued)
(V
= 3.3V, V
= 12V, V
= V /2, V = (V
- V
- V )/Gain, V
= V , R = 10kΩ to GND, T = -40°C to +125°C,
DD
CM
SENSE
FS
FS
DD
OH
OL
SHDN
DD
L
A
unless otherwise noted. Typical values are at T = +25°C.) (Note 2)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
from 250mV to 2.5V,
OUT
1500
Gain = 50, within 12-bit accuracy
V
from 250mV to 2.5V,
OUT
Gain = 100, within 12-bit
accuracy
1500
1800
4000
Settling Time
t
S
µs
V
from 250mV to 2.5V,
OUT
Gain = 200, within 12-bit
accuracy
V
from 250mV to 2.5V,
OUT
Gain = 500, within 12-bit
accuracy
R
R
= 0Ω
500
ISO
ISO
Capacitive Load
C
pF
L
= 20Ω
2200
Note 2: All devices are 100% production tested at T = +25°C. All temperature limits are guaranteed by design.
A
Note 3: V
is calculated by applying two values of V
(10% of full-scale range to 90% of full-scale range).
OS
SENSE
Note 4: Gain error is calculated by applying two values of V
(10% of full-scale range to 90% of full-scale range) and calculat-
SENSE
ing the error of the slope vs. the ideal.
Note 5: CMRR measurement is done at V
Note 6: PSRR measurement is done at V
= V /2 condition.
DD
= 1V condition.
OUT
OUT
Note 7: Parameter is guaranteed by design.
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
toc01b
toc01a
toc01c
34
32
30
28
26
24
22
20
25
24
23
22
21
20
19
18
17
GAIN = 100V/V
GAIN = 200V/V
VDD = 5.5V
GAIN = 50V/V
29
27
25
23
21
19
17
VDD = 3.3V
VDD = 5.5V
VDD = 5.5V
VDD = 3.3V
VDD = 3.3V
VDD = 1.7V
VDD = 1.7V
VDD = 1.7V
75
-50
-25
0
25
50
75
100 125
-50
-25
0
25
50
100 125
-50
-25
0
25
50
75
100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY CURRENT
vs. COMMON VOLTAGE
SUPPLY CURRENT
vs. TEMPERATURE
toc01d
30
32
31
30
29
28
27
26
25
24
23
22
GAIN = 500V/V
V
DD
= 3.3V
29
28
27
26
25
24
23
22
21
20
VDD = 5.5V
T
= -40ºC
A
VDD = 3.3V
T
= +125ºC
A
VDD = 1.7V
T
= +85ºC
14
A
T
= +25ºC
A
-50
-25
0
25
50
75
100 125
-1
4
9
19
(V)
24
29
34
TEMPERATURE (°C)
V
CM
INPUT OFFSET VOLTAGE HISTOGRAM
INPUT OFFSET VOLTAGE HISTOGRAM
GAIN ERROR HISTOGRAM
toc04b
toc04a
toc03
16
30
18
HISTOGRAM
HISTOGRAM
HISTOGRAM
GAIN = 200V/V
GAIN = 50V/V
GAIN = 100V/V
ALL GAIN
OPTIONS
14
12
10
8
16
14
12
10
8
25
20
15
10
5
6
6
4
4
2
2
0
0
0
-20-18-16-14-12-10 -8 -6 -4 -2
0
2
4
6
8
10 12 14 16 18 20
-6
-4
-2
0
2
4
6
-0.08 -0.06 -0.04 -0.02
0
0.02 0.04 0.06 0.08
INPUT OFFSET VOLTAGE ( μV )
INPUT OFFSET VOLTAGE (μV )
GAIN ERROR (%)
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
INPUT OFFSET VOLTAGE DRIFT HISTOGRAM
toc05
8
7
6
5
4
3
2
1
0
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
HISTOGRAM
ALL GAIN
GAIN = 50V/V
OPTIONS
V
= 5.5V
DD
V
= 3.3V
= 1.7V
DD
V
DD
-60 -50 -40 -30 -20 -10
0
10 20 30 40 50 60
INPUT OFFSET VOLTAGE DRIFT (nV/°C)
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
V
vs. I
SINK
V
vs. I
OL
OH
OUT
1000
900
800
700
600
500
400
300
200
100
0
900
V
DD
= 3.3V
V
= 3.3V
DD
800
700
600
500
400
300
200
100
0
0
2
4
I
6
8
10
0
1
2
3
4
I
5
6
7
8
9
10
(mA)
(mA)
SINK
OUT
GAIN ERROR
vs. INPUT COMMON-MODE VOLTAGE
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
toc09
30
25
20
15
10
5
0.05
0.04
0.03
0.02
0.01
0
GAIN = 50V/V
GAIN = 200
GAIN = 50VV
GAIN =
100V/V
0
-50
-25
0
25
50
75
100 125
-0.1 4.9 9.9 14.9 19.9 24.9 29.9 34.9
(V)
TEMPERATURE (°C)
V
CM
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
GAIN ERROR
vs. TEMPERATURE
GAIN ERROR vs. SUPPLY VOLTAGE
toc12
0.050
0.045
0.040
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0
0.08
0.06
0.04
0.02
0
GAIN = 50V/V
GAIN = 100V/V
GAIN = 500V/V
-0.02
-0.04
GAIN = 200 V/V
-50
-25
0
25
50
75
100 125
1.7 2.1 2.5 2.8 3.2 3.6 4.0 4.4 4.7 5.1 5.5
(V)
TEMPERATURE (°C)
V
DD
COMMON-MODE REJECTION RATIO
vs. TEMPERATURE
POWER-SUPPLY REJECTION RATIO
vs. TEMPERATURE
180
170
160
150
140
130
120
110
100
90
150
140
130
120
110
100
90
V
CM
= 0 to 36V
V
= -0.1V to +36V
CM
80
80
70
-50 -25
0
25
50
75 100 125
-50 -25
0
25
50
75 100 125
TEMPERATURE (ºC)
TEMPERATURE (ºC)
INPUT BIAS CURRENT
vs. INPUT COMMON-MODE VOLTAGE
INPUT BIAS CURRENT
vs. TEMPERATURE
toc15
toc16
200
0
12
10
8
FOR ALL GAIN
TA = -40°C
TA = +85°C
VCM = 12V
OPTIONS
TA =
+25°C
-200
-400
-600
-800
-1000
-1200
6
4
2
TA = +125°C
0
-2
-4
FOR ALL GAIN
OPTIONS
-1
3
7
11 15 19 23 27 31 35
-40 -25 -10
5
20 35 50 65 80 95 110 125
TEMPERATURE (°C)
INPUT COMMON-MODE VOLTAGE(V)
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
GAIN vs. FREQUENCY
INPUT-VOLTAGE NOISE vs. FREQUENCY
80
1000
100
10
70
G = 500V/V
60
50
40
30
20
10
0
G = 200V/V
G = 50V/V
G = 100V/V
-10
-20
0
0.1
1
10
100
1k
10k 100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
SMALL-SIGNAL INPUT STEP RESPONSE
0.1Hz TO 10Hz PEAK-TO-PEAK NOISE
(V = 3.3V, R = Open, G = 100V/V)
DD
L
MAX44284 toc20
MAX44284 toc19
6mV
V
IN
3mV
V
OUT
1µV/div
600mV
V
OUT
300mV
1s/div
400µs/div
LARGE-SIGNAL INPUT STEP RESPONSE
(V = 3.3V, R = Open)
STABILITY vs. CAPACITIVE
LOAD AND ISOLATION RESISTOR
CC
L
toc22
MAX44284 toc21
100000
10000
1000
100
30mV
STABLE
V
IN
3mV
3V
10
UNSTABLE
1
V
OUT
0.1
0.3V
0.01
100
1000
10000
100000 1000000
400µs/div
CAPACITIVE LOAD (pF)
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Pin Configurations
TOP VIEW
TOP VIEW
+
MAX44284
V
1
2
3
6
5
4
SHDN
OUT
RS-
DD
RS+
V
OUT
DD
MAX44284
A1
B1
A2
B2
A3
B3
GND
RS+
RS-
GND SHDN
SOT23
WLP
Pin Description
PIN
BUMP
WLP
NAME
FUNCTION
SOT23
Power-Supply Voltage Input. Bypass V
capacitors in parallel as close as possible to the device.
to GND with 0.1μF and 4.7μF
DD
1
A2
V
DD
2
3
4
5
6
B2
A1
B1
A3
B3
GND
RS+
Ground
External Sense Resistor Power-Side Connection
External Sense Resistor Load-Side Connection
RS-
OUT
SHDN
Output Voltage. V
is proportional to V
= V
- V
.
OUT
SENSE
RS+
RS-
Active-Low Shutdown Input. Connect to V
for normal operation.
DD
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
power dissipation in battery-powered systems, as well as
load regulation issues in low-voltage DC power supplies.
Detailed Description
The MAX44284 family features a single-supply; high-
accuracy unidirectional, current-sense amplifier in various
gain options and a -0.1V to 36V input common-mode
Working with error tolerances with very few internal
blocks in this architecture is instrumental in achieving a
gain error of less than 0.20% over the entire temperature
range of -40°C to +125°C.
range that is independent of supply voltage (V ). The
DD
MAX44284 is ideal for many battery-powered, handheld
devices because it uses only maximum 31.2μA quiescent
supply current to extend battery life. The device’s low
input offset voltage, tight gain error, and low temperature
drift characteristics allow the use of small-sense resistors
for current measurements to improve power-supply con-
version efficiency and accuracy of measurements. This
feature allows monitoring of power-supply load current
even if the rail is shorted to ground. High-side current
monitoring does not interfere with the ground path of the
load being measured, making the IC particularly useful in
a wide range of high-reliability systems.
Applications Information
Input Differential Signal Range
The MAX44284’s input structure is optimized for sens-
ing small differential signals as low as 3.4mV full scale
(V ) for high efficiency with lowest power dissipation in
FS
the sense resistor, or 110mV full scale for high dynamic
range. The input differential signal range is determined
by the following equation for the MAX44248 family.
V
DD
V
=
SENSE RANGE
(
)
Because of its extended common-mode range below
ground, this part can also be used as a low-side current
sensing element.
GAIN
The input differential voltage range is estimated for
from 1.7V to 5.5V for different gain values of the
V
DD
Shutdown
MAX44284 as shown in Table 1.
The MAX44284 features active-low logic shutdown input
to reduce the supply current. Drive SHDN high for normal
operation. Drive SHDN low to place the device in shut-
down mode. In shutdown mode, the supply current drawn
Ideally, the maximum load current develops the full-scale
sense voltage across the current-sense resistor. Choose
the gain needed to yield the maximum output voltage
required for the application:
from the V
is less than 1μA (max).
DD
V
= GAIN × V
SENSE
OUT
Precision
The MAX44284 uses capacitive-coupled Instrumentation
amplifier architecture that enables the part to achieve
over the top common-mode voltage ranges, high power
efficiency, high gain accuracy, and low-power design.
Choosing the Sense Resistor
Voltage Loss
A high R
value causes the power-source voltage
SENSE
to drop due to IR loss. For minimal voltage loss, use the
Low Offset Voltage and Low Gain Error
lowest R value.
SENSE
The MAX44284 utilizes Capacitive-Coupled Chopper
Instrumentation Amplifier (CCIA) architecture to achieve
a low-input offset voltage of less than 10µA. These tech-
niques also enable extremely low-input offset voltage drift
Accuracy
Use the below linear equation to calculate total error:
over time and temperature to 50nV/°C. The precision V
specification allows accurate current measurements with
OS
V
= GAIN ± GE × V
± GAIN × V
SENSE OS
(
)
(
)
OUT
lower values of current-sense resistors, thus reducing
Table 1. V
Input Range
SENSE
PART
MAX44284F
MAX44284H
MAX44284W
MAX44284E
GAIN (V/V)
V
RANGE (mV) with V
(1.7V)
V
RANGE (mV) with V
(5.5V)
SENSE
DD
SENSE
DD
50
34
17
110
55
100
200
500
8.5
3.4
27.5
11
Maxim Integrated
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
A high R
value allows lower currents to be mea-
SENSE
sured more accurately because offsets are less significant
when the sense voltage is larger. Note that the toler-
ance and temperature coefficient of the chosen resistors
directly affect the precision of any measurement sys-
R
SENSE
LOAD
R
IN
R
IN
tem. For best performance, select R
to provide
SENSE
C
C
IN
IN
approximately maximum input differential sense voltage of
110mV (MAX44284F) or 55mV (MAX44284H) or 27.5mV
(MAX44284W) or 11mV (MAX44284E) of sense voltage for
the full-scale current in each application. Sense resistors of
5mΩ to 100mΩ are available with 1% accuracy or better.
RS+
RS-
MAX44284
OUT
Efficiency and Power Dissipation
2
At high current levels, the I R losses in R
can be
SENSE
significant. This should be taken into consideration when
choosing the resistor value and its power dissipation
(wattage) rating. The sense resistor’s value will drift if it
GND
Figure 1. Differential Input Filtering
is allowed to heat up excessively. The precision V
of
OS
the MAX44284 allows the use of small sense resistors to
reduce power dissipation and reduce hot spots.
R
SENSE
Kelvin Connections
LOAD
Because of the high currents that may flow through
R
R
IN
IN
R
based on the application, take care to eliminate
SENSE
C
IN
solder and parasitic trace resistance from causing errors
in the sense voltage. Either use a four-terminal current-
sense resistor or use Kelvin (force and sense) PCB layout
techniques.
RS+
RS-
MAX44284
OUT
Input Filtering
Some applications of current-sense amplifiers need to
measure currents accurately even in the presence of both
differential and common-mode ripple, as well as a wide
variety of input transient conditions.
GND
Figure 2. Input Common-Mode Filtering
The MAX44284 allows two methods of filtering to help
improve performance in the presence of input common-
mode voltage and input differential voltage transients.
Figure 1 shows a differential input filter. The capacitor
additional DC error is accumulated as offset voltage and
increased gain error.
V
= R × I
+ DR × I
OFFSET IN BIAS
(
)
(
)
OS
IN
C
across RS+ and RS- along with the resistor R helps
IN
IN
filter against input differential voltages and prevents them
from reaching the MAX44284. The corner frequency of
DR is the resistance mismatch in R at RS+ and RS-.
IN
IN
If DR is too small, its effect can be neglected. Since
IN
this filter is determined by the choice of R , C . Figure 2
IN IN
I
of the MAX44284 is smaller than 2nA, and if we
OFFSET
shows a common-mode input filter. The choice of capaci-
want to make sure V
is lesser than 1µV range, choosing
OS
tance depends on corner frequency after R is chosen.
IN
In case of mismatch or error in application design, an
R
< V
(
÷ I
OS OFFSET
)
IN
Maxim Integrated
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
For gain error, it depends on its input impedance and R .
Note that load capacitance greater than approximately
2nF may cause instability unless a series resistor is pres-
ent to help isolate the capacitor from the amplifier output.
Output stability with different values of load capacitor
and isolation resistor is shown in TOC22 of the Typical
Operating Characteristics.
IN
−R
IN
GainError =
2 × Z
IN
Avoid additional gain error shift due to the effect of R .
IN
For gain error, the MAX44284 is 0.15%. If the margin of
Bidirectional Application
additional effect of R results in a gain error shift of less
IN
Battery-powered systems may require a precise bidirectional
current-sense amplifier to accurately monitor the battery’s
charge and discharge currents. Measurements of the two
separate outputs with respect to GND yield an accurate
measure of the charge and discharge currents, respectively
(Figure 4).
than 0.02%, then:
0.02%
R
<
= 600Ω
IN
2 × Z
IN
So R can be chosen ≤ 500Ω.
IN
Output Filtering
The internal architecture of the MAX44284 suppresses the DC
offset, 1/f noise, and accumulates at higher frequencies so that
they can be filtered out. Hence, minute AC disturbances
can be observed at 10kHz and 20kHz. It is recommended
to add an output filter after the MAX44284 to avoid noise
and unwanted frequency disturbances at the output with
4kHz -3dB f (see Figure 3).
c
(Suggested values of C and R: 22nF and 1.8kΩ, respectively.)
LOAD
C
IN
MAX44284
R
R
IN
RS-
R
R
C
IN2
SENSE
OUT
IN
RS+
C
C
IN
V
BATT
Figure 3. Filtering
Maxim Integrated
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
I
LOAD
R
SENSE
TO WALL-CUBE
CHARGER
V
BATT
UP TO 36V
LOAD
RS+
RS-
RS+
RS-
V
= 3.3V
DD
OUT
MAX44284
OUT
MAX44284
µC
ADC
ADC
Figure 4. Bidirectional Application
Ordering Information
PART
GAIN (V/V)
50
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
6 WLP
TOP MARK
+CX
MAX44284FAWT+
MAX44284FAUT+
MAX44284FAUT/V+T*
MAX44284HAWT+
MAX44284HAUT+
MAX44284WAWT+
MAX44284WAUT+
MAX44284EAWT+
MAX44284EAUT+
50
6 SOT23
6 SOT23
6 WLP
+ACSF
—
50
100
+CY
100
6 SOT23
6 WLP
+ACSG
+CZ
200
200
6 SOT23
6 WLP
+ACSH
+DA
500
500
6 SOT23
+ACSI
+Denotes a lead(Pb)-free/RoHS-compliant package
*Future product—contact factory for availability.
Chip Information
PROCESS: BiCMOS
Maxim Integrated
│ 14
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MAX44284
36V, Input Common-Mode, High-Precision,
Low-Power Current-Sense Amplifier
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
12/13
5/14
6/14
9/14
1/15
11/17
6/18
7/18
8/18
5/19
0
1
2
3
4
5
6
7
8
9
Initial release
—
Updated Typical Operating Characteristics and the Ordering Information
Corrected General Description and updated Electrical Characteristics globals
Released MAX44284E and updated the Electrical Characteristics
Revised Benefits and Features section
8, 13
1–4
3, 13
1
Corrected typo in Output Filtering section
12
Updated TOC22
8
Updated Ordering Information table
13
Updated Package Information section and Typical Operating Characteristics
Updated Typical Operating Characteristics and Output Filtering section
2, 8
9, 13
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2019 Maxim Integrated Products, Inc.
│ 15
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