MAX4080TASA [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： | MAX4080TASA |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 76V, High-Side, Current-Sense Amplifiers with Voltage Output |
| 文件： | 总15页 (文件大小：409K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2562; Rev 0; 10/02
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
General Description
Features
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 Wide 4.5V to 76V Input Common-Mode Range
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
0.1ꢀ Full-Scale Accuracꢁ
output level (V
= 0V). The charging current is rep-
o Low 100µV Input Offset Voltage
SENSE
resented by an output voltage from V
discharge current is given from V
to V , while
CC
REF
to GND.
o Independent Operating Supplꢁ Voltage
o 75µA Supplꢁ Current (MAX4080)
REF
For maximum versatility, the 76V input voltage range
applies independently to both supply voltage (V
)
CC
o Reference Input for Bidirectional OUT (MAX4081)
o Available in a Space-Saving 8-Pin µMAX Package
and common-mode input voltage (V
). High-side
RS+
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.
Ordering Information
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
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 µMAX
8 SO
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.
MAX4080FAUA
MAX4080FASA
MAX4080TAUA
MAX4080TASA
MAX4080SAUA
MAX4080SASA
MAX4081FAUA
MAX4081FASA
MAX4081TAUA
MAX4081TASA
MAX4081SAUA
MAX4081SASA
8 µMAX
8 SO
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.
8 µMAX
8 SO
8 µMAX
8 SO
8 µMAX
8 SO
Applications
Automotive (12V, 24V, or 42V Batteries)
Selector Guide appears at end of data sheet.
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/SO
µMAX/SO
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas 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
CC
V
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 4.5ꢀW/°C above +70°C).............362ꢀW
8-Pin SO (derate 5.88ꢀW/°C above +70°C)................471ꢀW
Operating Teꢀperature Range .........................-40°C to +125°C
Junction Teꢀperature......................................................+150°C
Storage Teꢀperature Range.............................-65°C to +150°C
Lead Teꢀperature (soldering, 10s) .................................+300°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.......................................................... 20ꢀA
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
, unless otherwise noted. Typical values are at T = +25°C.) (Notes 1, 2)
MAX
A
PARAMETER
SYMBOL
CONDITIONS
Inferred froꢀ PSRR test
Inferred froꢀ CMRR test (Note 3)
MIN
4.5
TYP
MAX
76
UNITS
Operating Voltage Range
Coꢀꢀon-Mode Range
V
V
V
CC
C
4.5
76
MVR
MAX4080
MAX4081
75
103
0.01
5
190
190
2
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+
12
RS+ RS-
MAX4080F/MAX4081F
MAX4080T/MAX4081T
MAX4080S/MAX4081S
MAX4080F/MAX4081F
MAX4080T/MAX4081T
MAX4080S/MAX4081S
T
1000
250
100
5
Full-Scale Sense Voltage (Note 4)
Gain
V
ꢀV
V/V
%
SENSE
A
20
V
60
= +25°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)
1.2
0.6
1
MIN
MAX
= +25°C
= -40°C to +85°C
= T to T
0.1
V
= V
= 48V
CC
RS+
Input Offset Voltage
V
ꢀV
OS
(Note 6)
1.2
MIN
MAX
Coꢀꢀon-Mode Rejection Ratio
Power-Supply Rejection Ratio
CMRR
PSRR
V
V
= 48V, V
= 4.5V to 76V
= 4.5V to 76V
100
100
124
122
dB
dB
CC
RS+
= 48V, V
RS+
CC
MAX4080F/MAX4081F,
= 1000ꢀV
V
SENSE
V
= 4.5V, V
RS+
CC
= 48V, V
=
REF1A
MAX4080T/MAX4081T,
= 250ꢀV
(V
V
-
)
CC
OUT High Voltage
V
= 2.5V,
0.15
0.27
V
REF1B
V
SENSE
OH
I
(sourcing) =
OUT
+500µA (Note 8)
MAX4080S/MAX4081S,
= 100ꢀV
V
SENSE
2
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
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
, unless otherwise noted. Typical values are at T = +25°C.) (Notes 1, 2)
MAX
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
2.5V, V
-1000ꢀV (for
MAX4081 only)
=
ꢀV
OL
SENSE
I
(sinking) =
OUT
23
55
6
100µA
REF1A = REF1B Input Voltage
Range (MAX4081 Only)
(V
REF
-
Inferred froꢀ REF1A rejection ratio,
V = V
REF1A
1.5
3
V
V
GND)
REF1B
REF1A Input Voltage Range
(MAX4081 Only)
(V
-
Inferred froꢀ REF1A rejection ratio,
REF1A
GND)
12
V
= GND
REF1B
REF1A Rejection Ratio
(MAX4081 Only)
V
V
= V
= 48V, V
= 0V,
SENSE
CC
RS+
80
108
0.500
250
dB
= V
= 1.5V to 6V
REF1A
REF1B
REF/REF1A Ratio
(MAX4081 Only)
V
V
= 10V, V
= GND,
REF1B
REF1A
0.497
0.503
= V
= 48V (Note 2)
RS+
CC
REF1A Input Iꢀpedance
(MAX4081 Only)
V
= GND
kΩ
REF1B
_______________________________________________________________________________________
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 = 20pF,
LOAD
CC
RS+
to T
REF1A
REF1B
SENSE
RS+
RS-
LOAD
T
= T
, unless otherwise noted. Typical values are at T = +25°C.) (Notes 1, 2)
A
MIN
MAX A
PARAMETER
SYMBOL
CONDITION
MIN
TYP
MAX
UNITS
MAX4080F/T/S
MAX4081F/T/S
250
150
20
V
= V
=
RS+
CC
Bandwidth
BW
kHz
48V, V
= 2.5V
OUT
V
V
= 10ꢀV to 100ꢀV
= 100ꢀV to 10ꢀV
SENSE
SENSE
OUT Settling Tiꢀe to 1% of Final
Value
µs
20
Capacitive-Load Stability
Output Resistance
No sustained oscillations
500
0.1
50
pF
Ω
R
V
V
= 100ꢀV
SENSE
OUT
Power-Up Tiꢀe
= V
= 48V, V = 100ꢀV (Note 9)
SENSE
µs
µs
CC
RS+
Saturation Recovery Tiꢀe
(Notes 9,10)
50
Note 1: All devices are 100% production tested at T = +25°C. All teꢀperature liꢀits 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.
REF
REF1A
REF1B
V
is defined as V
- V
.
SENSE
RS+
RS-
Note 3: The coꢀꢀon-ꢀode range at the low end of 4.5V applies to the ꢀost positive potential at RS+ or RS-. Depending on the
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
Note 5: V is:
applies to MAX4081 only.
SENSE
SENSE
MAX4080F, 10ꢀV to 1000ꢀV
MAX4080T, 10ꢀV to 250ꢀV
MAX4080S, 10ꢀV to 100ꢀV
MAX4081F, -500ꢀV to +500ꢀV
MAX4081T, -125ꢀV to +125ꢀV
MAX4081S, -50ꢀV to +50ꢀV
Note 6: V is extrapolated froꢀ the gain accuracy test for the MAX4080 and ꢀeasured as (V
- V
)/A at V
= 0V, for the
SENSE
OS
OUT
REF
V
MAX4081.
Note 7: V
is:
SENSE
MAX4080F, 500ꢀV
MAX4080T, 125ꢀV
MAX4080S, 50ꢀV
MAX4081F/T/S, 0V
V
= V
= 2.5V
REF1B
REF1A
Note 8: Output voltage is internally claꢀped 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
Typical Operating Characteristics
(V
= V
= 48V, V
= 0V, C
= 20pF, R
= ∞, T = +25°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
GAIN ACCURACY vs. TEMPERATURE
INPUT OFFSET VOLTAGE HISTOGRAM
0.5
0.4
35
300
250
200
150
100
50
30
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
75 100 125
-125 -100 -75 -50 -25
0 25 50 75 100 125
-50 -25
0
25 50
100 125 150
75
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
-0.05
-0.10
-0.15
-0.20
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
V
= 48V
RS+
S VERSION
-100
-110
-120
-130
F VERSION
-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
MAX4080F/T/S
SMALL-SIGNAL GAIN vs. FREQUENCY
MAX4081F/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
= 10mV
V
= 100mV
OUT P-P
SENSE
MAX4080S
MAX4080T
MAX4081S
MAX4081T
-50
-60
-70
-80
-90
MAX4080F
MAX4081F
-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
= 20pF, R
= ∞, T = +25°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
MAX4081
SUPPLY CURRENT vs. V
MAX4080
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
85
65
4
16
28
40
(V)
52
64
76
4
16
28
40
(V)
52
64
76
-50 -25
0
25
50
75 100 125
V
V
TEMPERATURE (°C)
CC
CC
MAX4081
SUPPLY CURRENT vs. TEMPERATURE
V
vs. I
HIGH VOLTAGE
(SOURCING)
V
vs. I
LOW VOLTAGE
OUT
OUT
OUT
(SINKING)
OUT
300
250
200
150
100
50
115
110
105
100
95
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
A
70
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
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
(SINKING) (µA)
OUT
OUT
MAX4080F
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080T
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080S
SMALL-SIGNAL TRANSIENT RESPONSE
MAX4080 toc16
MAX4080 toc17
MAX4080 toc18
INPUT
5mV/div
INPUT
5mV/div
INPUT
5mV/div
OUTPUT
25mV/div
OUTPUT
100mV/div
OUTPUT
300mV/div
20µs/div
20µs/div
20µs/div
6
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Typical Operating Characteristics (continued)
(V
= V
= 48V, V
= 0V, C
= 20pF, R
= ∞, T = +25°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
10mV/div
INPUT
2.5mV/div
INPUT
1mV/div
OUTPUT
50mV/div
OUTPUT
50mV/div
OUTPUT
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
400mV/div
INPUT
100mV/div
INPUT
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
400mV/div
INPUT
100mV/div
INPUT
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
= 20pF, R
= ∞, T = +25°C, unless otherwise noted.)
CC
RS+
SENSE
LOAD
LOAD
A
MAX4080F
SATURATION RECOVERY RESPONSE
MAX4080T
STARTUP DELAY
(V = 4.5V)
CC
(V
= 250mV)
V
-TRANSIENT RESPONSE
MAX4080 toc28
SENSE
CC
MAX4080 toc29
MAX4080 toc30
V
= 20V
RS+
= 20V STEP
V
CC
5V/div
V
= 40V
CC
V
REF1
CC
= V
V
= 2.5V
REF2
INPUT
500mV/div
V
CC
(0 TO 10V)
5V/div
V
= 20V
CC
V
OUT
1V/div
OUTPUT
2V/div
OUTPUT
2.5V/div
4µs/div
20µs/div
100µs/div
8
_______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
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.
2
2
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
- V
REF
) is
SENSE
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 froꢀ the
The MAX4080/MAX4081 unidirectional and bidirectional
high-side, current-sense aꢀplifiers feature a 4.5V to
76V input coꢀꢀon-ꢀode range that is independent of
supply voltage. This feature allows the ꢀonitoring 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 2), cre-
. Since the internal-sense
SENSE
ating a sense voltage, V
SENSE
aꢀplifier’s inverting input has high iꢀpedance, negligible
current flows through RG2 (neglecting the input bias
current). Therefore, the sense aꢀplifier’s inverting input
voltage equals V
- (I
)(R
). The aꢀpli-
SOURCE
LOAD
SENSE
supply voltage (V ). The MAX4080/MAX4081 ꢀonitors
CC
fier’s open-loop gain forces its noninverting input to the
current through a current-sense resistor and aꢀplifies
the voltage across the resistor. The MAX4080 senses
current unidirectionally, while the MAX4081 senses cur-
rent bidirectionally.
saꢀe voltage as the inverting input. Therefore, the drop
across RG1 equals V
. The internal current ꢀirror
SENSE
ꢀultiplies I
by a current gain factor, β, to give I
=
RG1
A2
β ✕ IRG1. Aꢀplifier A2 is used to convert the output
current to a voltage and then sent through aꢀplifier A3.
Total gain = 5V/V for MAX4080F, 20V/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 coꢀꢀon-ꢀode, input-sense voltage (V
RS+
side current ꢀonitoring does not interfere with the
ground path of the load being ꢀeasured, ꢀaking the
MAX4080/MAX4081 particularly useful in a wide range
of high-voltage systeꢀs.
The MAX4081 input stage differs slightly froꢀ the
MAX4080 (Figure 3). Its topology allows for ꢀonitoring
of bidirectional currents through the sense resistor.
When current flows froꢀ RS+ to RS-, the MAX4081
ꢀatches the voltage drop across the external sense
Battery-powered systeꢀs require a precise bidirectional
current-sense aꢀplifier to accurately ꢀonitor 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-
ꢀinals of the internal aꢀplifier A1 are kept constant and
an accurate ꢀeasureꢀent of the sense voltage is
achieved. In the following aꢀplifier stages of the
MAX4081, the output signal of aꢀplifier A2 is level-
current is represented by an output voltage froꢀ V
REF
to
to V , while discharge current is given froꢀ V
CC
REF
GND. Measureꢀents 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
SENSE
SYSTEM LOAD
AND CHARGER
V
OUT
= 10V
5V
RS-
RS+
V
CC
V
SENSE
MAX4081T
REF1A
-250mV
= GND
250mV
5V
-5V
REF1B
OUT
V
OUT
V
= V
= 5V
REF1B
REF1A
GND
DISCHARGE CURRENT
Figure 1. MAX4081T OUT Transfer Curve
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 2. MAX4080 Functional Diagram
that swings above V
voltage for positive-sense volt-
for negative-sense voltages.
Set the full-scale output range by selecting R
the appropriate gain version of the MAX4080/
MAX4081.
and
REF
REF
SENSE
ages and below V
is equal to V
V
OUT
when V
is equal to zero.
REF
SENSE
10 ______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Table 1. Tꢁpical 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
0.125
0.050
5.000
1.250
0.500
50.000
12.500
5.000
1000
1000
1000
100
100
100
10
5
500
125
50
2.5
20
60
5
2.5
3.0
2.5
2.5
3.0
2.5
2.5
3.0
500
125
50
20
60
5
500
125
50
10
20
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
0.250
1000
1000
1000
100
100
100
10
5
1000
250
100
1000
250
100
500
250
100
5.0
5.0
6.0
5.0
5.0
6.0
2.5
5.0
6.0
20
60
5
0.100
10.000
2.500
20
60
5
1.000
50.000
25.000
10.000
10
20
60
10
External References (MAX4081)
For the bidirectional MAX4081, the V reference level
Applications Information
Recommended Component Values
Ideally, the ꢀaxiꢀuꢀ load current develops the full-
scale sense voltage across the current-sense resistor.
Choose the gain needed to yield the ꢀaxiꢀuꢀ 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 ꢀode,
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, 1000ꢀV
SENSE
for gain of 5V/V, 250ꢀV for gain of 20V/V, 100ꢀV 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
/2 when V
REF1A
equals zero.
OUT
SENSE
In applications ꢀonitoring a high current, ensure that
R
is able to dissipate its own I2R loss. If the resis-
In either ꢀode, 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 ꢀay drift
output swings below the reference voltage for negative
current-sensing (V < V ).
or it ꢀay fail altogether.
RS+
RS-
The MAX4080/MAX4081 sense a wide variety of cur-
rents with different sense-resistor values. Table 1 lists
coꢀꢀon 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
V
CC
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
= 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 eliꢀinate parasitic trace resistance froꢀ
causing errors in the sense voltage. Either use a four-
terꢀinal 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 1000ꢀV for the 5V/V gain version,
250ꢀV for the 20V/V gain version, and 100ꢀV for the
60V/V gain version.
Dynamic Range Consideration
Although the MAX4081 have fully syꢀꢀetrical 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 froꢀ REF to V
and lower froꢀ 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 ꢀust con-
sider the dynaꢀic range of current ꢀonitored in both
directions and choose the supply voltage and the refer-
ence voltage (REF) to ꢀake sure the output swing
above and below REF is adequate to handle the swings
without clipping or running out of headrooꢀ.
power-source voltage to degrade through IR loss. For
ꢀiniꢀal voltage loss, use the lowest R value.
SENSE
• Accuracꢁ: A high R
value allows lower cur-
SENSE
rents to be ꢀeasured ꢀore accurately. This is due to
offsets becoꢀing less significant when the sense
voltage is larger. For best perforꢀance, select
R
to provide approxiꢀately 1000ꢀV (gain of
SENSE
5V/V), 250ꢀV (gain of 20V/V), or 100ꢀV (gain of
60V/V) of sense voltage for the full-scale current in
each application.
Power-Supply Bypassing and Grounding
For ꢀost applications, bypass V
to GND with a 0.1µF
CC
ceraꢀic capacitor. In ꢀany applications, V
can be
CC
connected to one of the current ꢀonitor terꢀinals (RS+
or RS-). Because V is independent of the ꢀonitored
• Efficiencꢁ and Power Dissipation: At high current
levels, the I2R 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 ꢀight 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 ꢀiniꢀize output disturbance.
This resistance and the decoupling capacitor reduce
the rise tiꢀe of the transient. For ꢀost applications, 1kΩ
in conjunction with a 0.1µF bypass capacitor work well.
• Inductance: Keep inductance low if I
has a
SENSE
large high-frequency coꢀponent. Wire-wound resis-
tors have the highest inductance, while ꢀetal filꢀ is
soꢀewhat better. Low-inductance, ꢀetal-filꢀ resis-
tors are also available. Instead of being spiral-
wrapped around a core, as in ꢀetal-filꢀ or wire-
wound resistors, they are a straight band of ꢀetal
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 ꢀiniꢀizing errors due to the large
charge and discharge currents in the systeꢀ.
12 ______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Power Management
The bidirectional capability of the MAX4081 ꢀakes it an
R
SENSE
excellent candidate for use in sꢀart battery packs. In
the application diagraꢀ (Figure 5), the MAX4081 ꢀoni-
tors the charging current into the battery as well as the
discharge current out of the battery. The ꢀicrocon-
troller stores this inforꢀation, allowing the systeꢀ to
query the battery's status as needed to ꢀake systeꢀ
power-ꢀanageꢀent decisions.
RS+
RS-
V
CC
MAX4081
REF1A
REF1B
GND
1.8V
SYSTEM
POWER
MANAGEMENT
AND
BATTERY
OUT
CHARGER
CIRCUITRY
SERIAL
INTERFACE
Selector Guide
PART
GAIN (V/V)
I
SENSE
µC
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
20
20
60
60
5
Figure 5. MAX4081 Used In Smart-Battery Application
Typical Operating Circuit
5
I
SENSE
20
20
60
60
SYSTEM
LOAD
V
= 4.5V TO 76V
CC
R
SENSE
RS+
RS-
V
CC
MAX4080
OUT
GND
Chip Information
TRANSISTOR COUNT: 185
PROCESS: Bipolar
______________________________________________________________________________________ 13
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Package Information
(The package drawing(s) in this data sheet ꢀay not reflect the ꢀost current specifications. For the latest package outline inforꢀation,
go to www.maxim-ic.com/packages.)
4X S
8
8
MILLIMETERS
INCHES
DIM MIN
MAX
MAX
MIN
-
-
0.043
0.006
0.037
0.014
0.007
0.120
1.10
0.15
0.95
0.36
0.18
3.05
A
0.002
0.030
0.010
0.005
0.116
0.05
0.75
0.25
0.13
2.95
A1
A2
b
E
H
ÿ 0.50±0.1
c
D
e
0.0256 BSC
0.65 BSC
0.6±0.1
E
H
0.116
0.188
0.016
0∞
0.120
2.95
4.78
0.41
0∞
3.05
5.03
0.66
6∞
0.198
0.026
6∞
L
1
1
α
S
0.6±0.1
0.0207 BSC
0.5250 BSC
BOTTOM VIEW
D
TOP VIEW
A1
A2
A
c
α
e
L
b
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0036
J
1
14 ______________________________________________________________________________________
76V, High-Side, Current-Sense Amplifiers with
Voltage Output
Package Information (continued)
(The package drawing(s) in this data sheet ꢀay not reflect the ꢀost current specifications. For the latest package outline inforꢀation,
go to www.maxim-ic.com/packages.)
INCHES
MILLIMETERS
DIM
A
MIN
MAX
0.069
0.010
0.019
0.010
MIN
1.35
0.10
0.35
0.19
MAX
1.75
0.25
0.49
0.25
0.053
0.004
0.014
0.007
N
A1
B
C
e
0.050 BSC
1.27 BSC
E
0.150
0.228
0.016
0.157
0.244
0.050
3.80
5.80
0.40
4.00
6.20
1.27
E
H
H
L
VARIATIONS:
INCHES
1
MILLIMETERS
DIM
D
MIN
MAX
0.197
0.344
0.394
MIN
4.80
8.55
9.80
MAX
5.00
N
8
MS012
AA
TOP VIEW
0.189
0.337
0.386
D
8.75 14
10.00 16
AB
D
AC
D
C
A
B
0∞-8∞
e
A1
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0041
B
1
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2002 Maxiꢀ Integrated Products
Printed USA
is a registered tradeꢀark of Maxiꢀ Integrated Products.
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