Maxim MAX4372FEUK-T Low-cost, sot23, micropower, high-side current-sense amplifier with voltage output Datasheet

19-1548; Rev 0; 10/99
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
High-side current monitoring is especially useful in battery-powered systems since it does not interfere with
the ground path of the battery charger. The input common-mode range of 0 to +28V is independent of the
supply voltage and ensures that the current-sense
feedback remains viable even when connected to a 2cell battery pack in deep discharge.
The user can set the full-scale current reading by
choosing the device (T, F, or H) with the desired voltage gain and selecting the appropriate external sense
resistor. This capability offers a high level of integration
and flexibility, resulting in a simple and compact current-sense solution. For higher bandwidth applications,
refer to the MAX4173T/F/H data sheet.
Applications
Power-Management Systems
Features
♦ Low-Cost, Compact Current-Sense Solution
♦ 30µA Supply Current
♦ +2.7V to +28V Operating Supply
♦ 0.18% Full-Scale Accuracy
♦ Low 1.5Ω Output Impedance
♦ Three Gain Versions Available
+20V/V (MAX4372T)
+50V/V (MAX4372F)
+100V/V (MAX4372H)
♦ Wide 0 to +28V Common-Mode Range,
Independent of Supply Voltage
♦ Available in Space-Saving SOT23-5 Package
Ordering Information
PART
TEMP. RANGE PIN-PACKAGE
TOP
MARK
MAX4372TEUK-T -40°C to +85°C 5 SOT23-5
ADIU
MAX4372TESA
-40°C to +85°C 8 SO
MAX4372FEUK-T -40°C to +85°C 5 SOT23-5
MAX4372FESA
-40°C to +85°C 8 SO
—
ADIV
—
MAX4372HEUK-T -40°C to +85°C 5 SOT23-5
ADIW
MAX4372HESA
-40°C to +85°C 8 SO
—
Note: Gain values are as follows: +20V/V for the T version,
+50V/V for the F version, and +100V/V for the H version.
General-System/Board-Level Current Monitoring
Notebook Computers
Portable/Battery-Powered Systems
Smart-Battery Packs/Chargers
Cell Phones
Typical Operating Circuit
Precision-Current Sources
Pin Configurations
ILOAD
TOP VIEW
GND
OUT
VCC
1
2
5
RS-
VCC 1
N.C. 2
MAX4372T/F/H
4
RS+
8
RS+
7
N.C.
3
6
RS-
OUT 4
5
N.C.
GND
3
GND
MAX4372T/F/H
MAX4372T/F/H
A/D
CONVERTER
VCC
+2.7V TO +28V
0.1µF
SOT23-5
SO
RS-
RSENSE
OUT
VCC
VSENSE
LOAD/
BATTERY
RS+
VIN
0 TO 28V
________________________________________________________________ Maxim Integrated Products
1
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For small orders, phone 1-800-835-8769.
MAX4372T/F/H
General Description
The MAX4372 low-cost, precision, high-side currentsense amplifier is available in a tiny, space-saving
SOT23-5 package. Offered in three gain versions (T =
+20V/V, F = +50V/V, and H = +100V/V), this device
operates from a single +2.7V to +28V supply and consumes only 30µA. It features a voltage output that eliminates the need for gain-setting resistors and is ideal for
today’s notebook computers, cell phones, and other
systems where battery/DC current monitoring is critical.
MAX4372T/F/H
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
ABSOLUTE MAXIMUM RATINGS
VCC, RS+, RS- to GND ...........................................-0.3V to +30V
OUT to GND ...........................................................-0.3V to +15V
Differential Input Voltage (VRS+ - VRS-) ..............................±0.3V
Current into Any Pin..........................................................±10mA
Continuous Power Dissipation (TA = +70°C)
5-Pin SOT23 (derate 7.1mW/°C above +70°C).............571mW
8-Pin SO (derate 5.88mW/°C above +70°C).................471mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec). ............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VRS+ = 0 to +28V, VCC = +2.7V to +28V, VSENSE = 0, RLOAD = 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
(Note 2)
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VCC
2.7
28
V
Common-Mode Input Range
(Note 3)
VCMR
0
28
V
Common-Mode Rejection
CMR
Supply Current
Leakage Current
ICC
IRS+, IRSIRS+
Input Bias Current
IRSFull-Scale Sense Voltage
(Note 4)
VSENSE
Full-Scale Accuracy
(Note 5)
VRS+ > 2V
85
VRS+ > 2V, VSENSE = 5mV
30
60
µA
0.05
1.2
µA
VCC = 0
VRS+ > 2V
0
1
VRS+ ≤ 2V
-25
2
VRS+ > 2V
0
2
VRS+ ≤ 2V
-50
150
Gain = +100V/V
100
±0.18
VSENSE = 100mV, VCC = 12V,
VRS+ = 12V (Note 6)
2
mV
±3
%
±6
VSENSE = 100mV, VCC = 28V,
VRS+ = 28V (Note 6)
±0.15
±7
VSENSE = 100mV, VCC = 12V,
VRS+ = 0.1V (Note 6)
±1
±28
VSENSE = 6.25mV, VCC = 12V,
VRS+ = 12V (Note 7)
±0.15
%
OUT Low Voltage
OUT High Voltage
µA
2
Gain = +20V/V or +50V/V
VSENSE = 100mV, VCC = 12V,
VRS+ = 12V, TA = +25°C (Note 6)
Total OUT Voltage Error
(Note 5)
dB
VCC = 2.7V
VCC - VOH
IOUT = 10µA
2.6
IOUT = 100µA
9
65
0.1
0.25
VCC = 2.7V, IOUT = -500µA
_______________________________________________________________________________________
mV
V
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
(VRS+ = 0 to +28V, VCC = +2.7V to +28V, VSENSE = 0, RLOAD = 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical values are
at TA = +25°C.) (Note 1)
PARAMETER
-3dB Bandwidth
SYMBOL
BW
CONDITIONS
VRS+ = 12V,
VCC = 12V,
CLOAD = 10pF
MIN
275
VSENSE = 100mV,
gain = +50V/V
200
VSENSE = 100mV,
gain = +100V/V
110
VSENSE = 6.25mV
50
MAX4372T
Gain
TYP
VSENSE = 100mV,
gain = +20V/V
UNITS
kHz
20
MAX4372F
50
MAX4372H
100
Gain Accuracy
VSENSE = 20mV
to 100mV
TA = +25°C
VSENSE = 6.25mV to
100mV
20
OUT Settling Time to 1% of
Final Value
Gain = +20V/V,
VCC = 12V,
VRS+ = 12V,
CLOAD = 10pF
VSENSE = 100mV to
6.25mV
20
Capacitive Load Stability
MAX
±0.25
TA = -40°C to +85°C
V/V
±2.5
±5.5
%
µs
No sustained oscillations
OUT Output Resistance
ROUT
VSENSE = 100mV
Power-Supply Rejection
PSR
VOUT = 2V, VRS+ > 2V
75
1000
pF
1.5
Ω
85
dB
Power-Up Time to 1% of
Final Value
VCC = 12V, VRS+ = 12V,
VSENSE = 100mV, CLOAD = 10pF
0.5
ms
Saturation Recovery Time
(Note 8)
VCC = 12V, VRS+ = 12V, CLOAD = 10pF
0.1
ms
Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Note 2: Guaranteed by PSR test.
Note 3: Guaranteed by OUT Voltage Error test.
Note 4: Output voltage is internally clamped not to exceed 12V.
Note 5: Total OUT voltage error is the sum of gain and offset voltage errors.
Note 6: Measured at IOUT = -500µA (RLOAD = 4kΩ for gain = +20V/V, RLOAD = 10kΩ for gain = +50V/V, RLOAD = 20kΩ for gain =
+100V/V).
Note 7: +6.25mV = 1/16 of +100mV full-scale voltage (C/16).
Note 8: The device will not reverse phase when overdriven.
_______________________________________________________________________________________
3
MAX4372T/F/H
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VCC = +12V, VRS+ = 12V, VSENSE = 100mV, TA = +25°C, unless otherwise noted.)
AV = +100V/V
AV = +50V/V
30.0
35
AV = +20V/V
27.5
20
15
8
12
16
20
24
-40
28.0
-15
10
35
60
85
VSENSE = 5mV
0
4
8
12
16
20
24
TOTAL OUTPUT ERROR vs. VSENSE
POWER-SUPPLY REJECTION
vs. FREQUENCY
1.0
-0.6
-45
-50
-55
AV = +100V/V
0.5
AV = +50V/V
PSR (dB)
OUTPUT ERROR (%)
G = +50V/V
G = +20V/V
-40
28
MAX4372T toc06
1.5
-0.8
AV = +20V/V
0
-60
-65
-70
-75
-80
-0.5
-1.0
-85
15
20
25
30
-90
0
50
1.4
0.8
G = +50V/V
G = +100V/V
0.4
G = +20V/V
10
15
20
300
100
1k
-0.2
25
COMMON-MODE VOLTAGE (V)
30
AV = +100V/V
-0.4
100k
TOTAL OUTPUT ERROR vs. TEMPERATURE
AV = +50V/V
-0.3
10k
FREQUENCY (Hz)
AV = +20V/V
-0.1
GAIN ACCURACY (%)
1.0
5
250
GAIN ACCURACY vs. TEMPERATURE
1.2
0
200
0
MAX4372T toc07
1.6
0.2
150
VSENSE (mV)
TOTAL OUTPUT ERROR
vs. COMMON-MODE VOLTAGE
0.6
100
-0.5
-0.6
-0.7
1.0
0.8
0.6
0.4
AV = +50V/V
0.2
0
-0.2
-0.4
-0.8
-0.6
-0.9
-0.8
-1.0
MAX4372T toc09
10
TOTAL OUTPUT ERROR (%)
5
MAX4372T toc08
0
-1.0
SUPPLY VOLTAGE (V)
4
AV = +20V/V
29.0
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
-0.4
0
AV = +50V/V
29.5
COMMON-MODE VOLTAGE (V)
-0.2
-1.2
30.0
TEMPERATURE (°C)
0.4
0
0
28
30.5
SUPPLY VOLTAGE (V)
G = +100V/V
0.2
VSENSE = 5mV
MAX4372T toc05
4
MAX4372 toc04
0
31.0
28.5
5
0.6
OUTPUT ERROR (%)
25
10
VSENSE = 5mV
25.0
30
AV = +100V/V
31.5
SUPPLY CURRENT (µA)
32.5
32.0
MAX4372T toc02
MAX4372 toc01
40
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
35.0
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
MAX4372 toc03
SUPPLY CURRENT vs. SUPPLY VOLTAGE
OUTPUT ERROR (%)
MAX4372T/F/H
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
AV = +100V/V
AV = +20V/V
-1.0
-40
-15
10
35
TEMPERATURE (°C)
60
85
-40
-15
10
35
TEMPERATURE (°C)
_______________________________________________________________________________________
60
85
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
MAX4372T
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4372F
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4372H
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4372T toc10
MAX4372T toc11
MAX4372T toc12
30mV
30mV
VSENSE
30mV
VSENSE
VSENSE
10mV
10mV
600mV
VOUT
10mV
1.5V
VOUT
3V
VOUT
200mV
1V
0.5V
20µs/div
20µs/div
20µs/div
MAX4372F
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4372T
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4372T toc14
MAX4372T toc13
150mV
VSENSE
150mV
VSENSE
50mV
50mV
3V
7.5V
VOUT
VOUT
2.5V
1V
20µs/div
20µs/div
MAX4372H
LARGE-SIGNAL TRANSIENT RESPONSE
SMALL-SIGNAL GAIN vs. FREQUENCY
MAX4372T toc15
MAX4372T toc16
3
2
1
100mV
VSENSE
G = +50V/V
0
10V
GAIN (dB)
0
G = +20V/V
-1
-2
-3
G = +100V/V
-4
VOUT
-5
-6
0
-7
-8
20µs/div
1k
10k
100k
1M
FREQUENCY (Hz)
_______________________________________________________________________________________
5
MAX4372T/F/H
Typical Operating Characteristics (continued)
(VCC = +12V, VRS+ = 12V, VSENSE = 100mV, TA = +25°C, unless otherwise noted.)
MAX4372T/F/H
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
Pin Description
PIN
NAME
FUNCTION
SOT23-5
1
SO
3
GND
Ground
2
4
OUT
Output Voltage. VOUT is proportional to the magnitude of VSENSE (VRS+ - VRS-).
3
1
VCC
Supply Voltage
4
8
RS+
Power Connection to the External Sense Resistor
5
6
RS-
Load-Side Connection to the External Sense Resistor
—
2, 5, 7
N.C.
No Connection. Not internally connected.
_______________Detailed Description
The MAX4372 high-side current-sense amplifier features a 0 to +28V input common-mode range that is
independent of supply voltage. This feature allows the
monitoring of current flow out of a battery in deep discharge, and also enables high-side current sensing at
voltages far in excess of the supply voltage (VCC).
Current flows through the sense resistor, generating a
sense voltage (Figure 1). Since A1’s inverting input is
high impedance, the voltage on the negative terminal
equals VIN - VSENSE. A1 forces its positive terminal to
match its negative terminal; therefore, the voltage
across RG1 (VIN - V1-) equals VSENSE. This creates a
current to flow through RG1 equal to VSENSE / RG1. The
transistor and current mirror amplify the current by a
factor of β. This makes the current flowing out of the
current mirror equal to:
IM = β VSENSE / RG1
A2’s positive terminal presents high impedance, so this
current flows through RGD, with the following result:
V2+ = RGD β · VSENSE / RG1
R1 and R2 set the closed-loop gain for A2, which
amplifies V2+, yielding:
VOUT = RGD · β · VSENSE / RG1 (1 + R2 / R1)
The gain of the device equals:
VOUT
= RGD · β (1 + R2 / R1) / RG1
VSENSE
__________Applications Information
Recommended Component Values
The MAX4372 operates over a wide variety of current
ranges with different sense resistors. Table 1 lists common resistor values for typical operation of the
MAX4372.
6
VIN
0 TO +28V
RG1
+2.7V
TO
+28V
RS+
V1+
VCC
A1
RSENSE
VSENSE
RSV1CURRENT
MIRROR
RGD
IM
TO
LOAD
MAX4372T/F/H
OUT
ILOAD
RG2
V2+
A2
V2-
R2
R1
GND
Figure 1. Functional Diagram
Choosing RSENSE
Given the gain and maximum load current, select
RSENSE such that VCC - VOUT does not exceed +0.25V
and VOUT does not exceed +10V. To measure lower
currents more accurately, use a high value for RSENSE.
A higher value develops a higher sense voltage, which
overcomes offset voltage errors of the internal current
amplifier.
In applications monitoring very high current, ensure
RSENSE is able to dissipate its own I2R losses. If the
resistor’s rated power dissipation is exceeded, its value
may drift or it may fail altogether, causing a differential
voltage across the terminals in excess of the absolute
maximum ratings.
_______________________________________________________________________________________
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
FULL-SCALE LOAD
CURRENT,
ILOAD (A)
CURRENT-SENSE
RESISTOR,
RSENSE (mΩ)
0.1
1000
1
100
5
20
10
10
Using a PC Board Trace as RSENSE
If the cost of RSENSE is an issue and accuracy is not
critical, use the alternative solution shown in Figure 2.
This solution uses copper PC board traces to create a
sense resistor. The resistivity of a 0.1-inch-wide trace of
2-ounce copper is about 30mΩ/ft. The resistance temperature coefficient of copper is fairly high (approximately 0.4%/°C), so systems that experience a wide
temperature variance must compensate for this effect.
In addition, self-heating will introduce a nonlinearity
error. Do not exceed the maximum power dissipation of
the copper trace.
For example, the MAX4372T (with a maximum load current of 10A and an RSENSE of 5mΩ) creates a full-scale
VSENSE of 50mV that yields a maximum VOUT of 1V.
RSENSE, in this case, requires about 2 inches of 0.1inch-wide copper trace.
GAIN
(V/V)
FULL-SCALE OUTPUT
VOLTAGE (FULL-SCALE
VSENSE = 100mV),
VOUT (V)
20
2.0
50
5.0
100
10.0
20
2.0
50
5.0
100
10.0
20
2.0
50
5.0
100
10.0
20
2.0
50
5.0
100
10.0
INPUT
0.3in COPPER
MAX4372T/F/H
Table 1. Recommended Component Values
LOAD/BATTERY
RSENSE
0.1in COPPER
0.3in COPPER
VSENSE
RS+
VCC
+2.7V TO +28V
MAX4372T/F/H
RS-
OUT
GND
Chip Information
TRANSISTOR COUNT: 225
Figure 2. Connections Showing Use of PC Board
_______________________________________________________________________________________
7
Low-Cost, SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
SOT5L.EPS
MAX4372T/F/H
Package Information
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.
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