MAX4080TAUV [MAXIM]
76V, High-Side, Current-Sense Amplifiers with Voltage Output; 76V ，高边，电流检测放大器，带有电压输出
| 型号： | MAX4080TAUV |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 76V, High-Side, Current-Sense Amplifiers with Voltage Output |
| 文件： | 总14页 (文件大小：326K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2562; Rev 4; 7/11
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
General Description
Features
o Wide 4.5V to 76V Input Common-Mode Range
The MAX4080/MAX4081 are high-side, current-sense
amplifiers with an input voltage range that extends from
4.5V to 76V making them ideal for telecom, automotive,
backplane, and other systems where high-voltage cur-
rent monitoring is critical. The MAX4080 is designed for
unidirectional current-sense applications and the
MAX4081 allows bidirectional current sensing. The
MAX4081 single output pin continuously monitors the
transition from charge to discharge and avoids the
need for a separate polarity output. The MAX4081
requires an external reference to set the zero-current
o Bidirectional or Unidirectional I
SENSE
o Low-Cost, Compact, Current-Sense Solution
o Three Gain Versions Available
5V/V (MAX4080F/MAX4081F)
20V/V (MAX4080T/MAX4081T)
60V/V (MAX4080S/MAX4081S)
o
0.1% Full-Scale Accuracy
o Low 100µV Input Offset Voltage
o Independent Operating Supply Voltage
o 75µA Supply Current (MAX4080)
output level (V
= 0V). The charging current is rep-
SENSE
resented by an output voltage from V
to V , while
CC
REF
to GND.
discharge current is given from V
o Reference Input for Bidirectional OUT (MAX4081)
o Available in a Space-Saving, 8-Pin µMAX Package
REF
For maximum versatility, the 76V input voltage range
applies independently to both supply voltage (V
)
CC
and common-mode input voltage (V
). High-side
RS+
Ordering Information
current monitoring does not interfere with the ground
path of the load being measured, making the
MAX4080/MAX4081 particularly useful in a wide range
of high-voltage systems.
PART
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
8 µMAX
8 µMAX
8 SO
MAX4080FAUA+
MAX4080FAUA/V+
MAX4080FASA+
MAX4080TAUA+
MAX4080TAUA/V+
MAX4080TASA+
MAX4080SAUA+
MAX4080SAUA/V+
MAX4080SASA+
The combination of three gain versions (5V/V, 20V/V,
60V/V = F, T, S suffix) and a user-selectable, external
sense resistor sets the full-scale current reading and its
proportional output voltage. The MAX4080/MAX4081
offer a high level of integration, resulting in a simple,
accurate, and compact current-sense solution.
8 µMAX
8 µMAX
8 SO
8 µMAX
8 µMAX
8 SO
The MAX4080/MAX4081 operate from a 4.5V to 76V sin-
gle supply and draw only 75µA of supply current. These
devices are specified over the automotive operating
temperature range (-40°C to +125°C) and are available
in a space-saving 8-pin µMAX® or SO package.
Ordering Information continued at end of data sheet.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Applications
Selector Guide appears at end of data sheet.
Automotive (12V, 24V, or 42V Batteries)
48V Telecom and Backplane Current
Measurement
Pin Configurations
Bidirectional Motor Control
Power-Management Systems
TOP VIEW
+
+
Avalanche Photodiode and PIN-Diode Current
Monitoring
RS+
1
2
3
4
8
7
6
5
RS-
RS+
1
2
3
4
8
7
6
5
RS-
V
N.C.
N.C.
V
CC
REF1A
REF1B
OUT
CC
General System/Board-Level Current Sensing
Precision High-Voltage Current Sources
MAX4080
MAX4081
N.C.
GND
N.C.
OUT GND
µMAX is a registered trademark of Maxim Integrated Products, Inc.
µMAX/SO
µMAX/SO
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND............................................................-0.3V to +80V
Continuous Power Dissipation (T = +70°C)
A
RS+, RS- to GND....................................................-0.3V to +80V
8-Pin µMAX (derate 4.5mW/°C above +70°C).............36±mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
Operating Temperature Range .........................-40°C to +1±5°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+±60°C
OUT to GND.............-0.3V to the lesser of +18V or (V
REF1A, REF1B to GND
+ 0.3V)
CC
(MAX4081 Only)....-0.3V to the lesser of +18V or (V
+ 0.3V)
CC
Output Short Circuit to GND.......................................Continuous
Differential Input Voltage (V + - V -)...............................±80V
RS
RS
Current into Any Pin..........................................................±±0mA
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.
DC ELECTRICAL CHARACTERISTICS
(V
= V
= 4.5V to 76V, V
= V
= 5V (MAX4081 only), V
= (V
- V ) = 0V, R
RS-
= 100kΩ, T = T
to
MIN
CC
RS+
REF1A
REF1B
SENSE
RS+
LOAD
A
T
MAX
, unless otherwise noted. Typical values are at T = +±5°C.) (Notes 1, ±)
A
PARAMETER
SYMBOL
CONDITIONS
Inferred from PSRR test
Inferred from CMRR test (Note 3)
MIN
4.5
TYP
MAX
76
UNITS
Operating Voltage Range
Common-Mode Range
V
V
V
CC
/MAX4081
C
4.5
76
MVR
MAX4080
MAX4081
75
103
0.01
5
190
190
±
V
= V
= 76V,
RS+
CC
Supply Current
I
µA
CC
no load
Leakage Current
Input Bias Current
I
I
, I
V
V
= 0V, V
= 76V
µA
µA
RS+ RS-
CC
CC
RS+
, I
= V
= 76V
RS+
1±
RS+ RS-
MAX4080F/MAX4081F
MAX4080T/MAX4081T
MAX4080S/MAX4081S
MAX4080F/MAX4081F
MAX4080T/MAX4081T
MAX4080S/MAX4081S
T
1000
±50
100
5
Full-Scale Sense Voltage (Note 4)
Gain
V
mV
V/V
%
SENSE
A
±0
V
60
= +±5°C
0.1
0.6
1
A
A
A
A
A
A
V
= V
= 48V
CC
RS+
Gain Accuracy
∆A
T
T
T
T
T
= -40°C to +85°C
= T to T
V
(Note 5)
1.±
0.6
1
MIN
MAX
= +±5°C
= -40°C to +85°C
= T to T
0.1
V
= V
= 48V
CC
RS+
Input Offset Voltage
V
mV
OS
(Note 6)
1.±
MIN
MAX
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
CMRR
PSRR
V
V
= 48V, V
= 4.5V to 76V
= 4.5V to 76V
100
100
1±4
1±±
dB
dB
CC
RS+
= 48V, V
RS+
CC
MAX4080F/MAX4081F,
= 1000mV
V
SENSE
V
= 4.5V, V
RS+
CC
= 48V, V
=
REF1A
MAX4080T/MAX4081T,
= ±50mV
(V
V
-
)
CC
OUT High Voltage
V
= ±.5V,
0.15
0.±7
V
REF1B
V
SENSE
OH
I
(sourcing) =
OUT
+500µA (Note 8)
MAX4080S/MAX4081S,
= 100mV
V
SENSE
2
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
DC ELECTRICAL CHARACTERISTICS (continued)
(V
= V
= 4.5V to 76V, V
= V
= 5V (MAX4081 only), V
= (V
- V ) = 0V, R
RS-
= 100kΩ, T = T
MIN
to
CC
RS+
REF1A
REF1B
SENSE
RS+
LOAD
A
T
MAX
, unless otherwise noted. Typical values are at T = +±5°C.) (Notes 1, ±)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
V
= V
= 48V,
RS+
CC
I
(sinking) = 10µA
4
15
OUT
= V
=
REF1B
REF1A
OUT Low Voltage
V
±.5V, V
-1000mV (for
MAX4081 only)
=
mV
OL
SENSE
I
(sinking) =
OUT
±3
55
6
100µA
REF1A = REF1B Input Voltage
Range (MAX4081 Only)
(V
REF
-
)
Inferred from REF1A rejection ratio,
V = V
REF1A
1.5
3
V
V
V
GND
REF1B
REF1A Input Voltage Range
(MAX4081 Only)
(V
-
Inferred from REF1A rejection ratio,
REF1A
1±
V
)
V
= V
REF1B GND
GND
REF1A Rejection Ratio
(MAX4081 Only)
V
V
= V
= 48V, V
= 0V,
SENSE
CC
RS+
80
108
0.500
±50
dB
= V
= 1.5V to 6V
REF1A
REF1B
REF/REF1A Ratio
(MAX4081 Only)
V
V
= 10V, V
= V
,
GND
REF1A
REF1B
= 48V (Note ±)
0.497
0.503
= V
CC
RS+
REF1A Input Impedance
(MAX4081 Only)
V
= V
kΩ
REF1B
GND
_______________________________________________________________________________________
3
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
AC ELECTRICAL CHARACTERISTICS
(V
= V
= 4.5V to 76V, V
= V
= 5V (MAX4081 only), V
= (V
- V ) = 0V, R
= 100kΩ, C = ±0pF,
LOAD
CC
RS+
REF1A
REF1B
SENSE
RS+
RS-
LOAD
T
A
= T
to T
, unless otherwise noted. Typical values are at T = +±5°C.) (Notes 1, ±)
MAX A
MIN
PARAMETER
SYMBOL
CONDITION
MIN
TYP
MAX
UNITS
MAX4080F/T/S
MAX4081F/T/S
±50
150
±0
V
= V
=
RS+
CC
Bandwidth
BW
kHz
48V, V
= ±.5V
OUT
V
V
= 10mV to 100mV
= 100mV to 10mV
SENSE
SENSE
OUT Settling Time to 1% of Final
Value
µs
±0
Capacitive-Load Stability
Output Resistance
No sustained oscillations
500
0.1
50
pF
Ω
R
V
V
= 100mV
SENSE
OUT
Power-Up Time
= V
= 48V, V = 100mV (Note 9)
SENSE
µs
µs
CC
RS+
Saturation Recovery Time
(Notes 9,10)
50
Note 1: All devices are 100% production tested at T = +±5°C. All temperature limits are guaranteed by design.
A
Note 2: V
is defined as the average voltage of V
and V
. REF1B is usually connected to REF1A or GND.
REF1B
REF
V
REF1A
is defined as V
- V
.
SENSE
RS+
RS-
Note 3: The common-mode range at the low end of 4.5V applies to the most positive potential at RS+ or RS-. Depending on the
/MAX4081
polarity of V
and the device’s gain, either RS+ or RS- can extend below 4.5V by the device’s typical full-scale value of
SENSE
V
.
SENSE
Note 4: Negative V
applies to MAX4081 only.
SENSE
Note 5: V is:
SENSE
MAX4080F, 10mV to 1000mV
MAX4080T, 10mV to ±50mV
MAX4080S, 10mV to 100mV
MAX4081F, -500mV to +500mV
MAX4081T, -1±5mV to +1±5mV
MAX4081S, -50mV to +50mV
Note 6: V is extrapolated from the gain accuracy test for the MAX4080 and measured as (V
- V
)/A at V
= 0V, for the
SENSE
OS
MAX4081.
OUT
REF
V
Note 7: V
is:
SENSE
MAX4080F, 500mV
MAX4080T, 1±5mV
MAX4080S, 50mV
MAX4081F/T/S, 0V
V
= V
= ±.5V
REF1B
REF1A
Note 8: Output voltage is internally clamped not to exceed 18V.
Note 9: Output settles to within 1% of final value.
Note 10:The device will not experience phase reversal when overdriven.
4
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
Typical Operating Characteristics
(V
= V
= 48V, V
= 0V, C
= ±0pF, R
= ∞, T = +±5°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
INPUT OFFSET VOLTAGE HISTOGRAM
GAIN ACCURACY vs. TEMPERATURE
300
250
200
150
100
50
35
30
0.5
0.4
0.3
25
20
15
10
5
0.2
0.1
0
0
-50
-0.1
-0.2
-0.3
-0.4
-0.5
-100
-150
-200
-250
-300
0
-50 -25
0
25 50
100 125 150
75
-125 -100 -75 -50 -25
0 25 50 75 100 125
-50 -25
0
25
50
75 100 125
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (µV)
TEMPERATURE (°C)
MAX4081F/T/S
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX4081F/T/S
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
GAIN ACCURACY vs. V
CC
0
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
V
= 48V
RS+
S VERSION
-0.05
-0.10
-0.15
-0.20
F VERSION
-120
-130
-120
-130
4
16
28
40
(V)
52
64
76
1
10
100
1k
10k
100k
1M
1
10
100
1k
10k
100k
1M
V
FREQUENCY (Hz)
FREQUENCY (Hz)
CC
MAX4081F/T/S
REFERENCE REJECTION RATIO
vs. FREQUENCY
MAX4081F/T/S
SMALL-SIGNAL GAIN vs. FREQUENCY
MAX4080F/T/S
SMALL-SIGNAL GAIN vs. FREQUENCY
50
45
40
35
30
25
20
15
10
5
50
45
40
35
30
25
20
15
10
5
0
-10
-20
-30
-40
V
= 100mV
P-P
V
= 10mV
OUT
SENSE
MAX4081S
MAX4081T
MAX4080S
MAX4080T
-50
-60
-70
-80
MAX4081F
MAX4080F
-90
-100
-110
-120
0
0
0.1
1
10
FREQUENCY (kHz)
100
1000
0.1
1
10
FREQUENCY (kHz)
100
1000
1
10
100
1k
10k
100k
FREQUENCY (Hz)
_______________________________________________________________________________________
5
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Typical Operating Characteristics (continued)
(V
= V
= 48V, V
= 0V, C
= ±0pF, R
= ∞, T = +±5°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
MAX4080
SUPPLY CURRENT vs. V
MAX4081
SUPPLY CURRENT vs. V
MAX4080
SUPPLY CURRENT vs. TEMPERATURE
CC
CC
125
120
115
110
105
100
95
85
115
110
105
100
95
NO LOAD
= 0V
V
= 2.5V
REF
V
NO LOAD
= 0V
SENSE
V
SENSE
80
75
70
65
60
90
85
80
75
90
70
65
85
4
16
28
40
(V)
52
64
76
-50 -25
0
25
50
75 100 125
4
16
28
40
(V)
52
64
76
V
TEMPERATURE (°C)
V
CC
CC
/MAX4081
MAX4081
SUPPLY CURRENT vs. TEMPERATURE
V
vs. I
HIGH VOLTAGE
(SOURCING)
V
vs. I
LOW VOLTAGE
OUT
OUT
OUT
(SINKING)
OUT
115
110
105
100
95
300
250
200
150
100
50
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
V
= V
= 2.5V
REF1B
REF1A
V
= 4.5V
CC
V
= 4.5V
CC
T
= +125°C
A
T
= +125°C
A
T
= +85°C
A
90
T
= +85°C
A
85
T
= +25°C
A
T
= +25°C
A
80
75
T
= 0°C
= -40°C
T
A
T
= 0°C
A
70
A
T
= -40°C
A
65
0
-50 -25
0
25
50
75 100 125
0
50 100 150 200 250 300 350 400 450 500
(SINKING) (µA)
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
TEMPERATURE (°C)
I
(SOURCING) (mA)
I
OUT
OUT
MAX4080F
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080T
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080S
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080 toc16
MAX4080 toc17
MAX4080 toc18
INPUT
INPUT
INPUT
5mV/div
5mV/div
5mV/div
OUTPUT
OUTPUT
OUTPUT
25mV/div
100mV/div
300mV/div
20µs/div
20µs/div
20µs/div
6
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
Typical Operating Characteristics (continued)
(V
= V
= 48V, V
= 0V, C
= ±0pF, R
= ∞, T = +±5°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
MAX4081F
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4081T
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4081S
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080 toc19
MAX4080 toc20
MAX4080 toc21
INPUT
INPUT
INPUT
10mV/div
2.5mV/div
1mV/div
OUTPUT
OUTPUT
OUTPUT
50mV/div
50mV/div
50mV/div
20µs/div
20µs/div
20µs/div
MAX4080F
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4080T
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4080S
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4080 toc22
MAX4080 toc23
MAX4080 toc24
INPUT
INPUT
INPUT
400mV/div
100mV/div
33mV/div
OUTPUT
2V/div
OUTPUT
2V/div
OUTPUT
2V/div
20µs/div
20µs/div
20µs/div
MAX4081F
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4081T
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4081S
LARGE-SIGNAL TRANSIENT RESPONSE
MAX4080 toc25
MAX4080 toc26
MAX4080 toc27
INPUT
INPUT
INPUT
400mV/div
100mV/div
33mV/div
OUTPUT
2V/div
OUTPUT
2V/div
OUTPUT
2V/div
20µs/div
20µs/div
20µs/div
_______________________________________________________________________________________
7
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Typical Operating Characteristics (continued)
(V
= V
= 48V, V
= 0V, C
= ±0pF, R
= ∞, T = +±5°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
MAX4080F
SATURATION RECOVERY RESPONSE
MAX4080T
STARTUP DELAY
(V = 4.5V)
CC
(V
SENSE
= 250mV)
V
CC
-TRANSIENT RESPONSE
MAX4080 toc28
MAX4080 toc29
MAX4080 toc30
V
= 20V
RS+
V
CC
V
= 40V
CC
V
REF1
= 20V STEP
REF2
CC
= V
5V/div
V
= 2.5V
INPUT
V
CC
500mV/div
(0 TO 10V)
5V/div
V
= 20V
CC
V
OUT
OUTPUT
2V/div
OUTPUT
2.5V/div
1V/div
4µs/div
1
20µs/div
100µs/div
8
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
Pin Description
PIN
NAME
FUNCTION
MAX4080
MAX4081
1
1
RS+
Power connection to the external-sense resistor.
Supply Voltage Input. Decouple V to GND with at least a 0.1µF capacitor to
CC
bypass line transients.
±
±
V
CC
3, 6, 7
4
3
4
N.C.
No Connection. No internal connection. Leave open or connect to ground.
Ground
GND
Voltage Output. For the unidirectional MAX4080, V
is proportional to
OUT
5
5
OUT
V
. For the bidirectional MAX4081, the difference voltage (V
SENSE
- V
REF
) is
OUT
proportional to V
and indicates the correct polarity.
SENSE
8
8
6
RS-
Load connection to the external sense resistor.
Reference Voltage Input: Connect REF1B to REF1A or to GND (see the External
Reference section).
—
REF1B
Reference Voltage Input: Connect REF1A and REF1B to a fixed reference
voltage (V
). V
is equal to V
when V is zero (see the External
SENSE
—
7
REF1A
REF
OUT
REF
Reference section).
Current Monitoring
Detailed Description
The MAX4080 operates as follows: current from the
The MAX4080/MAX4081 unidirectional and bidirectional
high-side, current-sense amplifiers feature a 4.5V to
76V input common-mode range that is independent of
supply voltage. This feature allows the monitoring of
current out of a battery as low as 4.5V and also enables
high-side current sensing at voltages greater than the
source flows through R
to the load (Figure ±), cre-
. Since the internal-sense
SENSE
ating a sense voltage, V
SENSE
amplifier’s inverting input has high impedance, negligible
current flows through RG± (neglecting the input bias
current). Therefore, the sense amplifier’s inverting input
voltage equals V
- (I
)(R
). The ampli-
SOURCE
LOAD
SENSE
supply voltage (V ). The MAX4080/MAX4081 monitors
CC
fier’s open-loop gain forces its noninverting input to the
same voltage as the inverting input. Therefore, the drop
current through a current-sense resistor and amplifies
the voltage across the resistor. The MAX4080 senses
current unidirectionally, while the MAX4081 senses cur-
rent bidirectionally.
across RG1 equals V
. The internal current mirror
SENSE
multiplies I
by a current gain factor, β, to give I
=
RG1
A±
β ꢀ IRG1. Amplifier A± is used to convert the output
current to a voltage and then sent through amplifier A3.
Total gain = 5V/V for MAX4080F, ±0V/V for the
MAX4080T, and 60V/V for the MAX4080S.
The 76V input voltage range of the MAX4080/MAX4081
applies independently to both supply voltage (V
)
CC
). High-
and common-mode, input-sense voltage (V
RS+
side current monitoring does not interfere with the
ground path of the load being measured, making the
MAX4080/MAX4081 particularly useful in a wide range
of high-voltage systems.
The MAX4081 input stage differs slightly from the
MAX4080 (Figure 3). Its topology allows for monitoring
of bidirectional currents through the sense resistor.
When current flows from RS+ to RS-, the MAX4081
matches the voltage drop across the external sense
Battery-powered systems require a precise bidirectional
current-sense amplifier to accurately monitor the bat-
tery’s charge and discharge. The MAX4081 charging
resistor, R
, by increasing the current through the
SENSE
Q1 and RG1. In this way, the voltages at the input ter-
minals of the internal amplifier A1 are kept constant and
an accurate measurement of the sense voltage is
achieved. In the following amplifier stages of the
MAX4081, the output signal of amplifier A± is level-
current is represented by an output voltage from V
REF
to
to V , while discharge current is given from V
CC
REF
GND. Measurements of OUT with respect to V
yield
REF
a positive and negative voltage during charge and dis-
charge, as illustrated in Figure 1 for the MAX4081T.
shifted to the reference voltage (V
= V
=
REF
REF1A
V
), resulting in a voltage at the output pin (OUT)
REF1B
_______________________________________________________________________________________
9
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
10V
I
I
CHARGE
CHARGE CURRENT
LOAD
4.5V TO 76V
BATTERY
V
R
SENSE
SYSTEM LOAD
AND CHARGER
SENSE
V
OUT
= 10V
5V
RS-
RS+
V
CC
V
SENSE
MAX4081T
REF1A
-250mV
250mV
5V
-5V
REF1B
OUT
V
= V
GND
OUT
V
REF1A
= V
REF1B
= 5V
GND
DISCHARGE CURRENT
Figure 1. MAX4081T OUT Transfer Curve
/MAX4081
V
SENSE
V
SENSE
I
LOAD
RS-
RS+
R
SENSE
RS+
RS-
R
R
G2
G1
MAX4081
R
G1
R
G2
RF
A2
A1
MAX4080
A1
Q1
Q2
OUT
Q1
125kΩ
125kΩ
CURRENT
MIRROR
CURRENT
MIRROR
REF1B
REF1A
I
A2
CURRENT
MIRROR
OUT
A2
A3
V
REF
GND
Figure 3. MAX4081 Functional Diagram
Figure ±. MAX4080 Functional Diagram
that swings above V
ages and below V
voltage for positive-sense volt-
for negative-sense voltages.
Note: For Gain = 5 (F), R
= R
= 160k.
= 60k.
REF
REF
G1
G±
G±
For Gain = ±0 (T), R
For Gain = 60 (S), R
= R
G1
G1
= R
= ±0k.
G±
V
is equal to V
when V
is equal to zero.
OUT
REF
SENSE
Set the full-scale output range by selecting R
and
SENSE
the appropriate gain version of the MAX4080/
MAX4081.
10 ______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
Table 1. Typical Component Values
FULL-SCALE
MAX4081 FULL-SCALE
OUTPUT VOLTAGE
FULL-SCALE LOAD
CURRENT, I (A)
CURRENT-SENSE
RESISTOR (mΩ)
GAIN
(V/V)
V
SENSE
(mV)
LOAD
(V
OUT
- V
V)
REF,
0.500
0.1±5
0.050
5.000
1.±50
0.500
50.000
1±.500
5.000
1000
1000
1000
100
100
100
10
5
±500
±1±5
±50
±±.5
±±.5
±3.0
±±.5
±±.5
±3.0
±±.5
±±.5
±3.0
±0
60
5
±500
±1±5
±50
±0
60
5
±500
±1±5
±50
10
±0
60
10
FULL-SCALE
FULL-SCALE LOAD
CURRENT, I (A)
CURRENT-SENSE
RESISTOR (mΩ)
GAIN
(V/V)
MAX4080 FULL-SCALE
OUTPUT VOLTAGE (V)
V
SENSE
(mV)
LOAD
1.000
0.±50
1000
1000
1000
100
100
100
10
5
1000
±50
100
1000
±50
100
500
±50
100
5.0
5.0
6.0
5.0
5.0
6.0
±.5
5.0
6.0
±0
60
5
0.100
10.000
±.500
±0
60
5
1.000
50.000
±5.000
10.000
10
±0
60
10
External References (MAX4081)
For the bidirectional MAX4081, the V reference level
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:
OUT
is controlled by REF1A and REF1B. V
is defined as
REF
the average voltage of V
and V
. Connect
REF1A
REF1B
REF1A and REF1B to a low-noise, regulated voltage
source to set the output reference level. In this mode,
V
equals V
when V
equals zero (see
SENSE
OUT
Figure 4).
REF1A
V
OUT
= V ꢀ A
SENSE V
Alternatively, connect REF1B to ground, and REF1A to a
low-noise, regulated voltage source. In this case, the out-
where V
is the full-scale sense voltage, 1000mV
SENSE
for gain of 5V/V, ±50mV for gain of ±0V/V, 100mV for
put reference level (V
) is equal to V
divided by
REF
REF1A
gain of 60V/V, and A is the gain of the device.
V
two. V
equals V
/± when V
REF1A
equals zero.
OUT
SENSE
In applications monitoring a high current, ensure that
R
is able to dissipate its own I±R loss. If the resis-
In either mode, the output swings above the reference
voltage for positive current-sensing (V > V ). The
SENSE
RS+
RS-
tor’s power dissipation is exceeded, its value may drift
or it may fail altogether.
output swings below the reference voltage for negative
current-sensing (V < V ).
RS+
RS-
The MAX4080/MAX4081 sense a wide variety of cur-
rents with different sense-resistor values. Table 1 lists
common resistor values for typical operation.
______________________________________________________________________________________ 11
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
I
= 0
I
= 0
LOAD
LOAD
R
R
SENSE
SENSE
LOAD
LOAD
RS+
RS-
RS+
RS-
V
CC
V
CC
REF1A
REF1A
10V
MAX4081
MAX4081
5V
REF1B
OUT
REF1B
OUT
GND
5V
5V
GND
Figure 4. MAX4081 Reference Inputs
The full-scale output voltage is V
/MAX4081
= R
ꢀ I
LOAD
REF
Because of the high currents that flow through R
,
OUT
SENSE
SENSE
ꢀ A , for the MAX4080 and V
= V ±
take care to eliminate parasitic trace resistance from
causing errors in the sense voltage. Either use a four-
terminal current-sense resistor or use Kelvin (force and
sense) PC board layout techniques.
(MAX)
V
ꢀ I
OUT
R
V
ꢀ A for the MAX4081.
SENSE
SENSE(MAX)
LOAD(MAX) V
is 1000mV for the 5V/V gain version,
±50mV for the ±0V/V gain version, and 100mV for the
60V/V gain version.
Dynamic Range Consideration
Although the MAX4081 have fully symmetrical bidirec-
Choosing the Sense Resistor
based on the following criteria:
Choose R
tional V
input capability, the output voltage range
SENSE
SENSE
is usually higher from REF to V
and lower from REF
CC
• Voltage Loss: A high R
value causes the
SENSE
to GND (unless the supply voltage is at the lowest end
of the operating range). Therefore, the user must con-
sider the dynamic range of current monitored in both
directions and choose the supply voltage and the refer-
ence voltage (REF) to make sure the output swing
above and below REF is adequate to handle the swings
without clipping or running out of headroom.
power-source voltage to degrade through IR loss. For
minimal voltage loss, use the lowest R value.
SENSE
• Accuracy: A high R
value allows lower cur-
SENSE
rents to be measured more accurately. This is due to
offsets becoming less significant when the sense
voltage is larger. For best performance, select
R
to provide approximately 1000mV (gain of
SENSE
5V/V), ±50mV (gain of ±0V/V), or 100mV (gain of
60V/V) of sense voltage for the full-scale current in
each application.
Power-Supply Bypassing and Grounding
For most applications, bypass V
to GND with a 0.1µF
CC
ceramic capacitor. In many applications, V
can be
CC
connected to one of the current monitor terminals (RS+
or RS-). Because V is independent of the monitored
• Efficiency and Power Dissipation: At high current
levels, the I±R losses in R
can be significant.
CC
SENSE
voltage, V
supply.
can be connected to a separate regulated
CC
Take this into consideration when choosing the
resistor value and its power dissipation (wattage)
rating. Also, the sense resistor’s value might drift if it
is allowed to heat up excessively.
If V
will be subject to fast-line transients, a series
CC
resistor can be added to the power-supply line of the
MAX4080/MAX4081 to minimize output disturbance.
This resistance and the decoupling capacitor reduce
the rise time of the transient. For most applications, 1kΩ
in conjunction with a 0.1µF bypass capacitor work well.
• Inductance: Keep inductance low if I
has a
SENSE
large high-frequency component. Wire-wound resis-
tors have the highest inductance, while metal film is
somewhat better. Low-inductance, metal-film resis-
tors are also available. Instead of being spiral-
wrapped around a core, as in metal-film or wire-
wound resistors, they are a straight band of metal
and are available in values under 1Ω.
The MAX4080/MAX4081 require no special considera-
tions with respect to layout or grounding. Consideration
should be given to minimizing errors due to the large
charge and discharge currents in the system.
12 ______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
/MAX4081
Power Management
The bidirectional capability of the MAX4081 makes it an
excellent candidate for use in smart battery packs. In
Typical Operating Circuit
I
SENSE
the application diagram (Figure 5), the MAX4081 moni-
tors the charging current into the battery as well as the
discharge current out of the battery. The microcon-
troller stores this information, allowing the system to
query the battery's status as needed to make system
power-management decisions.
SYSTEM
LOAD
V
CC
= 4.5V TO 76V
R
SENSE
RS+
RS-
V
CC
MAX4080
R
SENSE
OUT
GND
RS+
RS-
V
CC
MAX4081
REF1A
REF1B
GND
1.8V
SYSTEM
POWER
MANAGEMENT
AND
CHARGER
CIRCUITRY
BATTERY
Chip Information
OUT
PROCESS: Bipolar
SERIAL
INTERFACE
Ordering Information (continued)
µC
PART
TEMP RANGE
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
-40°C to +1±5°C
PIN-PACKAGE
8 µMAX
8 SO
MAX4081FAUA+
MAX4081FASA+
MAX4081TAUA+
MAX4081TASA+
MAX4081SAUA+
MAX4081SASA+
Figure 5. MAX4081 Used In Smart-Battery Application
8 µMAX
8 SO
Selector Guide
8 µMAX
8 SO
PART
GAIN (V/V)
I
SENSE
+Denotes a lead(Pb)-free/RoHS-compliant package.
MAX4080FAUA
MAX4080FASA
MAX4080TAUA
MAX4080TASA
MAX4080SAUA
MAX4080SASA
MAX4081FAUA
MAX4081FASA
MAX4081TAUA
MAX4081TASA
MAX4081SAUA
MAX4081SASA
5
Unidirectional
Unidirectional
Unidirectional
Unidirectional
Unidirectional
Unidirectional
Bidirectional
Bidirectional
Bidirectional
Bidirectional
Bidirectional
Bidirectional
5
±0
±0
60
60
5
Package Information
For the latest package outline information and land patterns
(footprints), go to www.maxim-ic.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.
5
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
±0
±0
60
60
PATTERN NO.
8 µMAX
8 SO
U8+1
S8+±
21-0036
21-0041
90-0092
90-0096
______________________________________________________________________________________ 13
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
0
1
2
3
4
10/02
11/08
5/09
Initial release
—
10
1
Added values for RG1 and RG2
Added lead-free and automotive parts to Ordering Information
Removed automotive part and added soldering temperature
Added automotive part designation
5/10
1, 2
1
7/11
/MAX4081
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2011 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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