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參數(shù)資料
| 型號： | MAX4173FESA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封裝： | 0.150 INCH, SOIC-8 |
| 文件頁數(shù)： | 7/12頁 |
| 文件大?。?/td> | 204K |
| 代理商： | MAX4173FESA |
M
Low-Cost, S OT 23, Voltage-Output,
High-S ide Current-S ense Amplifier
_______________________________________________________________________________________
7
Detailed Desc ription
The MAX4173 high-side current-sense amplifier fea-
tures a 0 to +28V input common-mode range that is
independent of supply voltage. This feature allows the
monitoring of current out of a battery in deep discharge
and also enables high-side current sensing at voltages
greater than the supply voltage (V
CC
).
The MAX4173 operates as follows: Current from the
source flows through R
SENSE
to the load (Figure 1). Since
the internal-sense amplifier’s inverting input has high
impedance, negligible current flows through RG2
(neglecting the input bias current). Therefore, the
sense amplifier’s inverting-input voltage equals
V
SOURCE
- (I
LOAD
)(R
SENSE
). The amplifier’s open-loop
gain forces its noninverting input to the same voltage as
the inverting input. Therefore, the drop across RG1
equals (I
LOAD
)(R
SENSE
). Since I
RG1
flows through RG1,
I
RG1
= (I
LOAD
)(R
SENSE
) / RG1. The internal current mirror
multiplies I
RG1
by a current gain factor,
β
, to give
I
RGD
=
β
·
I
RG1
. Solving I
RGD
=
β
·
(I
LOAD
)(R
SENSE
) /
RG1. Assuming infinite output impedance, V
OUT
= (I
RGD
)
(RGD). Substituting in for I
RGD
and rearranging, V
OUT
=
β
·
(RGD / RG1)(R
SENSE
·
I
LOAD
). The parts gain equals
β
·
RGD / RG1. Therefore, V
OUT
= (GAIN) (R
SENSE
)
(I
LOAD
), where GAIN = 20 for MAX4173T, GAIN = 50 for
MAX4173F, and GAIN = 100 for MAX4173H.
Set the full-scale output range by selecting R
SENSE
and
the appropriate gain version of the MAX4173.
Applic ations Information
Rec ommended Component V alues
The MAX4173 senses a wide variety of currents with
different sense resistor values. Table 1 lists common
resistor values for typical operation of the MAX4173.
Choosing R
S ENS E
To measure lower currents more accurately, use a high
value for R
SENSE
. The high value develops a higher
sense voltage that reduces offset voltage errors of the
internal op amp.
In applications monitoring very high currents, R
SENSE
must be able to dissipate the I
2
R 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 maxi-
mum ratings.
If I
SENSE
has a large high-frequency component, mini-
mize the inductance of R
SENSE
. Wire-wound resistors
have the highest inductance, metal-film resistors are
somewhat better, and low-inductance metal-film resis-
tors are best suited for these applications.
Using a PCB T rac e as R
S ENS E
If the cost of R
SENSE
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 approximately 30m
/ft. The resis-
tance-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, do not exceed the maximum power
dissipation of the copper trace.
For example, the MAX4173T (with a maximum load cur-
rent of 10A and an R
SENSE
of 5m
) creates a full-scale
V
SENSE
of 50mV that yields a maximum V
OUT
of 1V.
R
SENSE
in this case requires about 2 inches of 0.1 inch-
wide copper trace.
Output Impedanc e
The output of the MAX4173 is a current source driving a
12k
resistance. Resistive loading added to OUT
reduces the output gain of the MAX4173. To minimize
output errors for most applications, connect OUT to a
high-impedance input stage. When output buffering is
required, choose an op amp with a common-mode
input range and an output voltage swing that includes
ground when operating with a single supply. The op
R
SENSE
V
SOURCE
0 TO+28V
+3V TO+28V
RGD
= 12k
V
OUT
I
RG1
I
RGD
I
LOAD
R
G1
R
G2
RS-
RS+
OUT
GND
TOLOAD BATTERY
V
CC
CURRENT
MIRROR
A1
MAX4173
Figure 1. Functional Diagram
相關PDF資料 |
PDF描述 |
|---|---|
| MAX4173FEUT-T | Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier |
| MAX4173T | Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier |
| MAX4173TEUT-T | Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier |
| MAX4173HESA | Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier |
| MAX4173HEUT-T | Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX4173FESA+ | 功能描述:電流靈敏放大器 V-Out High-Side Current-Sense Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量: 共模抑制比（最小值）:110 dB 輸入補償電壓:80 uV 電源電壓-最大:5.5 V 電源電壓-最小:2.7 V 電源電流:350 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-16 封裝:Reel |
| MAX4173FESA+T | 功能描述:電流靈敏放大器 V-Out High-Side Current-Sense Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量: 共模抑制比（最小值）:110 dB 輸入補償電壓:80 uV 電源電壓-最大:5.5 V 電源電壓-最小:2.7 V 電源電流:350 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-16 封裝:Reel |
| MAX4173FESA-T | 功能描述:電流靈敏放大器 V-Out High-Side Current-Sense Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量: 共模抑制比（最小值）:110 dB 輸入補償電壓:80 uV 電源電壓-最大:5.5 V 電源電壓-最小:2.7 V 電源電流:350 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-16 封裝:Reel |
| MAX4173FEUT | 制造商:Maxim Integrated Products 功能描述:LOW-COST SOT23 HIGH-SIDE CURRENT-S - Bulk |
| MAX4173FEUT+ | 制造商:Maxim Integrated Products 功能描述:SP AMP CURRENT SENSE AMP SGL 28V 6PIN SOT-23 - Rail/Tube |
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