MAX49921 [MAXIM]
0 to 70V, High-Precision Current-Sense Amplifier;
| 型号： | MAX49921 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 0 to 70V, High-Precision Current-Sense Amplifier |
| 文件： | 总14页 (文件大小：432K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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0 to 70V, High-Precision Current-Sense
Amplifier
MAX49921
General Description
Benefits and Features
The MAX49921 is high-precision, unidirectional current-
sense amplifier (CSA) with an operating input common-
mode range from 0 to +70V, though the device is pro-
tected against input common-mode voltages down to -42V
and up to +80V, thus providing protection against reverse-
battery and high-voltage spikes. The MAX49921 is well-
suited for current monitoring of inductive loads, such as
DC motors and solenoids, where common-mode voltages
can become negative due to inductive kickback, reverse-
battery conditions, or transient events.
● AEC-Q100 Qualified for Automotive Applications
● ±0.5μV (typ) Input Offset Voltage
● ±0.05% (typ) Gain Error
● 0 to +70V Input Voltage Range
● -42V to +80V Protective Immunity
● 65kHz, -3dB Bandwidth
● 140dB DC CMRR
● Gain Options: 20V/V, 50V/V
● Rail-to-Rail Output
● 2mm x 3mm, 8-Pin TDFN Package
● -40°C to +125°C Automotive Temperature Range
The low input offset of ±0.5μV (typ) and low gain error of
±0.05% (typ) make this device best-suited for high-preci-
sion current measurements.
Ordering Information appears at end of data sheet.
The MAX49921 operates from a supply voltage of +2.7V
to +5.5V with a typical quiescent supply at 0.7mA. This
device is specified over the full -40°C to +125°C automo-
tive temperature range and is AEC-Q100 qualified. The
MAX49921 is offered in a 2mm x 3mm, 8-pin, side-wet-
table TDFN package with gain options of 20V/V and
50V/V.
Simplified Block Diagram
V
DD
RS+
RS-
OUT
LEVEL
SHIFTING
Applications
● Solenoid Current Sensing
● Battery Current Monitoring
MAX49921
● Current Monitoring of Inductive Loads
● High- and Low-Side Precision Current Sensing
● Supercapacitor Charge/Discharge Monitoring
● Precision High-Voltage Current Monitoring
● Automotive Current Sensing
GND
19-100848; Rev 1; 9/21
Ordering Information appears at end of data sheet.
© 2021 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.
One Analog Way, Wilmington, MA 01887 U.S.A. | Tel: 781.329.4700 | © 2021 Analog Devices, Inc. All rights reserved.
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
TABLE OF CONTENTS
General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
8 TDFN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electrical Characteristics (V
= 5V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
DD
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
MAX49921 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Recommended Component Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Choosing the Sense Resistor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Voltage Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Efficiency and Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Stray Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Important Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Power-Supply Bypassing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Solenoid Current Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
DC Motor Current Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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Analog Devices | 2
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Absolute Maximum Ratings
RS+ and RS- to GND .............................................. -42V to +80V
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
RS+ to RS- ............................................................................. ±2V
V
DD
to GND.............................................................. -0.3V to +6V
Continuous Power Dissipation (multilayer board) (T = +70°C,
derate 16.7mW/°C above +70°C)................................ 1333.3mW
A
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
8 TDFN
Package Code
T823Y+3C
21-100417
90-0091
Outline Number
Land Pattern Number
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θ
)
60°C/W
11°C/W
JA
Junction to Case (θ
)
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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Analog Devices | 3
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Electrical Characteristics (V
= 5V)
DD
= V
(V
= V
= +50V, V
= +5V, V
- V
= 1mV, T = -40°C to +125°C, unless otherwise noted. Typical values are
RS+
RS-
DD
SENSE
RS+
RS- A
at T = +25°C. (Note 1) )
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER-SUPPLY CHARACTERISTICS
Supply Voltage
V
Guaranteed by PSRR
No loads
2.7
5.5
1
V
DD
Supply Current
I
0.7
mA
µs
DD
Power-Up Time (Note 2)
t
Output settles to 1%
200
PWR_UP
CURRENT-SENSE AMPLIFIER / DC CHARACTERISTICS
Input-Protected
Common-Mode Range
V
(Note 3)
-42
0
+80
+70
V
V
CM_P
Input Common-Mode
Range
V
Guaranteed by CMRR
CM
Input Bias Current
I
, I
(Note 3)
(Note 3)
0.1
0.1
0.1
±30
±50
μA
µA
μA
RS+ RS-
Input Offset Current
Input Leakage Current
I
- I
RS+ RS-
I
I
V
DD
= 0V, V
= 70V (Note 3)
RS+, RS-
RS±
T
A
= +25ºC
±0.5
±0.5
-40ºC ≤ T ≤ +85ºC
A
G = 20V/V
G = 50V/V
-40ºC ≤ T
+125ºC
≤
A
±60
±12
±20
Input Offset Voltage
V
μV
OS
T = +25°C
A
-40°C ≤ T
+85°C
≤
A
-40°C ≤ T
+125°C
≤
A
±50
380
Input Offset Voltage Drift
TCV
nV/°C
dB
OS
Power-Supply Rejection
Ratio
PSRR
2.7V ≤ V
≤ 5.5V
108
130
125
DD
-40°C ≤ T
+85°C
≤
≤
A
A
140
140
Common-Mode
Rejection Ratio
CMRR
0 ≤ V
≤ +70V
dB
CM
-40°C ≤ T
+125°C
Input Capacitance
C
IN
RS+, RS- input
3
pF
G = 20V/V (MAX49921T)
G = 50V/V (MAX49921F)
100
90
Input Sense Voltage
V
mV
SENSE
G
Full-scale (FS) V
(MAX49921T)
= 100mV
SENSE
20
Gain
V/V
%
FS V
= 90mV (MAX49921F)
50
SENSE
T
A
= +25°C
±0.05
±0.1
±0.15
±0.2
Gain Error (Note 4)
GE
-40°C ≤ T ≤ +85°C
A
-40°C ≤ T ≤ +125°C
A
Nonlinearlity Error
Output Resistance
10mV ≤ V
≤ 95mV
0.1
0.2
%
Ω
SENSE
R
OUT
V
OUT
= V /2, I
= ±500μA
OUT
DD
Output Voltage Swing
High
V
0.015
-
DD
V
OH
Source 500μA
V
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Analog Devices | 4
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Electrical Characteristics (V
= 5V) (continued)
DD
= V
(V
= V
= +50V, V
= +5V, V
- V
= 1mV, T = -40°C to +125°C, unless otherwise noted. Typical values are
RS+
RS-
DD
SENSE
RS+
RS- A
at T = +25°C. (Note 1) )
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
15
UNITS
Sink 500μA
No load
Output Voltage Swing
Low
V
OL
mV
4
Output Short-Circuit
Current
I
Shorted to either V
or GND
DD
55
mA
SC
CURRENT-SENSE AMPLIFIER / AC CHARACTERISTICS
Signal Bandwidth
BW
All gain configurations V
> 5mV
SENSE
65
kHz
-3dB
2V
1.5V
output square wave, centered at
P-P
Output Slew Rate
SR
0.25
V/µs
AC Power-Supply
Rejection Ratio
AC PSRR
AC CMRR
f = 200kHz
35
58
dB
dB
AC Common-Mode
Rejection Ratio
f = 200kHz, 100mV sine wave
With 250Ω isolation resistor
Without any isolation resistor
20
nF
pF
Capacitive Load Stability
C
LOAD
200
Input Voltage Noise
Density
e
n
At 1kHz
75
20
nV/ Hz
√
Settling Time (Settling to
0.1%)
V
steps from 20% FS to 80% FS
SENSE
t
S
µs
(t = t = 5μs), C = 20pF
R
F
L
Note 1: All devices are 100% production tested at T = +25°C. Limits over the operating temperature range and relevant supply
A
voltage range are guaranteed by design and characterization.
Note 2: Output is high-Z during power-up.
Note 3: Guaranteed by design, not final production tested.
Note 4: Gain and offset voltage are calculated based on two point measurements: V
and V
. V
= 5mV and
SENSE1
SENSE1
SENSE2
V
= 40mV for G = 50V/V. V
= 10mV and V
= 100mV for G = 20V/V.
SENSE2
SENSE1
SENSE2
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Analog Devices | 5
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Typical Operating Characteristics
(V
= 5V, V
= 50V, V
= V
- V
= 1mV, T = +25°C, unless otherwise noted.)
RS- A
DD
CM
SENSE
RS+
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Analog Devices | 6
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Typical Operating Characteristics (continued)
(V
= 5V, V
= 50V, V
= V
- V
= 1mV, T = +25°C, unless otherwise noted.)
RS- A
DD
CM
SENSE
RS+
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Analog Devices | 7
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Typical Operating Characteristics (continued)
(V
= 5V, V
= 50V, V
= V
- V
= 1mV, T = +25°C, unless otherwise noted.)
RS- A
DD
CM
SENSE
RS+
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Analog Devices | 8
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Pin Configuration
MAX49921
TOP VIEW
V
GND GND OUT
DD
8
7
6
5
MAX49921
EP
+
1
2
3
4
RS+ RS- NC NC
TDFN
2mm x 3mm
Pin Description
PIN
1
NAME
RS+
FUNCTION
Positive Current-Sensing Input. Power side connects to external sense resistor.
Negative Current-Sensing Input. Load side connects to external sense resistor.
2
RS-
5
OUT
Current-Sense Voltage Output. V
is proportional to V
.
SENSE
OUT
Ground (connect pins 6 and 7 together at the IC). All ground pins should be connected to a solid
ground plane for best performance.
6, 7
GND
8
V
+2.7V to +5.5V Supply Voltage Input. Bypass V
No Connection. Not internally connected.
Exposed Pad. Internally connected to GND.
to GND with a 0.1μF capacitor.
DD
DD
3, 4
—
NC
EP
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Analog Devices | 9
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Detailed Description
The MAX49921 is a high-precision, current-sense amplifier (CSA) with an operating input common-mode range from 0 to
+70V, though the device is protected against input common-mode voltages down to -42V and up to +80V, thus providing
protection against reverse-battery and high-voltage spikes. The CSA is well-suited for current monitoring of inductive
loads such as DC motors and solenoids, where common-mode voltages can become negative due to inductive kickback,
reverse-battery conditions, or transient events.
The low input offset of ±0.5μV (typ) and low gain error of ±0.05% (typ) make the device best-suited for high-precision
current measurements. The MAX49921 runs from a single supply voltage of +2.7V to +5.5V, consumes 0.7mA (typ)
quiescent supply current, and features gains of 20V/V and 50V/V.
The MAX49921 is designed for unidirectional operation, allowing current measurements in one direction through the
sense resistor R
. The device output voltage can be estimated as follows:
SENSE
V
OUT
= V
x A
SENSE
V
where V
= (V
- V
) = the sense voltage across the R resistor, 100mV for gain of 20V/V, 90mV for
SENSE
SENSE
RS+
RS-
gain of 50V/V, and A is the gain of the device.
V
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Analog Devices | 10
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Applications Information
Recommended Component Values
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 using the following equation:
V
OUT
= V x A
FS V
where V is the full-scale sense voltage, 100mV for gain of 20V/V, 90mV for gain of 50V/V, and A is the gain of the
FS
V
device.
The MAX49921 senses a wide variety of currents with different sense-resistor values. In applications monitoring a high
2
current, ensure that R
is able to dissipate its own I R loss. If the resistor’s power dissipation exceeds the nominal
SENSE
value, its value may drift or it may fail altogether.
Choosing the Sense Resistor
Choose R
based on the following criteria:
SENSE
Voltage Loss
A high R
lowest R
value causes the power source voltage to degrade through IR loss. For minimal voltage loss, use the
value.
SENSE
SENSE
Accuracy
A high R
value allows lower currents measured more accurately. This is due to offsets becoming less significant
SENSE
when the sense voltage is larger. For best performance, select R
to provide approximately 100mV (gain of 20V/
SENSE
V), 90mV (gain of 50V/V) of sense voltage for the full-scale current in each application.
Efficiency and Power Dissipation
2
At high current levels, the I R losses in R
can be significant. Consider this when choosing the resistor value and
SENSE
its power dissipation (wattage) rating. In addition, the sense resistor’s value might drift if it heats up excessively.
Stray Inductance
The stray inductance due to package parasitics in the current sense resistor should be kept to a minimum. The
unwanted voltage error produced by the stray inductance is proportional to the magnitude of the load current. Wire-wound
resistors have the highest inductance, while metal film is comparably better. Low-inductance, metal-film resistors are also
available. Instead of being spiral wrapped around a core, as in metal-film or wire-wound resistors, they are straight bands
of metal and are available in values under 100mΩ.
Important Considerations
Due to the high currents that may flow through R
, be sure to eliminate solder and parasitic trace resistance to
SENSE
keep from causing errors in the sense voltage. Either use a four-terminal current sense resistor or use Kelvin (force and
sense) PCB layout techniques.
Power-Supply Bypassing
Power-supply bypass capacitors are recommended for best performance and should be placed as close as possible
to the supply V
and ground terminals of the device. A typical value for this supply bypass capacitor is 0.1μF (NP0/
DD
C0G type) close to the V /GND pins. The capacitors should be rated for at least twice the maximum expected applied
DD
voltage. Applications with noisy or high-impedance power supplies may require additional decoupling capacitors to reject
power-supply noise.
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Analog Devices | 11
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Typical Application Circuits
Solenoid Current Measurement
A solenoid is used to convert electrical energy into a mechanical movement to position an object like a car window. The
following figure shows the example circuit that uses the MAX49921 to measure the current in the solenoid with a low-
side shunt-sensing resistor. Even if the power supply is connected in reverse, the MAX49921 can still withstand up to
-42V without needing a reverse-protection diode.
POWER SUPPLY
5V
SOLENOID
V
DD
RS+
RS-
OUT
LEVEL
SHIFTING
ADC
CONTROLLER
MAX49921
GND
DC Motor Current Measurement
The following figure shows an example of high-side current sensing in a DC motor with the MAX49921. The high
common-mode voltage range of the MAX49921 makes it capable of surviving the kick-back voltages in motor switching.
The device is also protected up to -42V in case a reverse-battery connection occurs.
5V
POWER
SUPPLY
V
DD
RS+
RS-
OUT
LEVEL
SHIFTING
ADC
DC
MOTOR
M
MAX49921
CONTROLLER
GND
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Analog Devices | 12
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Ordering Information
PART NUMBER
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 TDFN
TOP MARK
BRR
GAIN
20V/V
20V/V
50V/V
50V/V
MAX49921TATA/VY+
MAX49921TATA/VY+T
MAX49921FATA/VY+
MAX49921FATA/VY+T
8 TDFN
BRR
8 TDFN
BRQ
8 TDFN
BRQ
+ Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
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Analog Devices | 13
MAX49921
0 to 70V, High-Precision Current-Sense Amplifier
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
10/20
9/21
0
1
Release for intro
Updated Electrical Characteristics and Ordering Information tables
—
4, 5, 13
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is
assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may
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