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參數(shù)資料
| 型號： | INA138 |
| 英文描述： | High-Side Measurement CURRENT SHUNT MONITOR |
| 中文描述： | 高側(cè)測量電流并聯(lián)監(jiān)視器 |
| 文件頁數(shù)： | 7/7頁 |
| 文件大小： | 69K |
| 代理商： | INA138 |
7
INA138, INA168
lower currents by minimizing the effects of offset, while low
values of R
S
minimize voltage loss in the supply line. For
most applications, best performance is attained with an R
S
value that provides a full-scale shunt voltage of 50mV to
100mV. Maximum input voltage for accurate measurements
is 500mV.
R
L
is chosen to provide the desired full-scale output voltage.
The output impedance of the INA138 Out terminal is very
high which permits using values of R
L
up to 500k
with
excellent accuracy. The input impedance of any additional
circuitry at the output should be much higher than the value
of R
L
to avoid degrading accuracy.
Some A/D converters have input impedances that will sig-
nificantly affect measurement gain. The input impedance of
the A/D converter can be included as part of the effective R
L
if its input can be modeled as a resistor to ground. Alterna-
tively, an op-amp can be used to buffer the A/D converter
input. See Figure 1 for recommended values of R
L
.
OUTPUT VOLTAGE RANGE
The output of the INA138 is a current, which is converted to
a voltage by the load resistor, R
L
. The output current remains
accurate within the
compliance voltage range
of the output
circuitry. The shunt voltage and the input common-mode
and power supply voltages limit the maximum possible
output swing. The maximum output voltage compliance is
limited by the lower of the two equations below:
V
out
max
= (V+) – 0.7V – (V
IN
+
– V
IN
–
)
(4)
or
V
out
max
= V
IN
(whichever is lower)
–
– 0.5V
(5)
BANDWIDTH
Measurement bandwidth is affected by the value of the load
resistor, R
L
. High gain produced by high values of R
L
will
yield a narrower measurement bandwidth (see Typical Per-
formance Curves). For widest possible bandwidth, keep the
capacitive load on the output to a minimum. Reduction in
bandwidth due to capacitive load is shown in the Typical
Performance Curves.
If bandwidth limiting (filtering) is desired, a capacitor can be
added to the output, as shown in Figure 3. This will not
cause instability.
APPLICATIONS
The INA138 is designed for current shunt measurement
circuits as shown in Figure 1, but its basic function is useful
in a wide range of circuitry. A creative engineer will find
many unforeseen uses in measurement and level shifting
circuits. A few ideas are shown.
FIGURE 2. Buffering Output to Drive A/D Converter.
I
S
OPA340
INA138
3
4
Z
IN
R
L
Buffer of amp drives A/D converter
without affecting gain.
FIGURE 3. Output Filter.
INA138
f
–3dB
=
1
2
π
R
L
C
L
V
O
f
–3dB
R
L
C
L
3
4
FIGURE 4. Offsetting the Output Voltage.
V
0
R
2
R
1
1
Gain Set by R
1
//R
2
Output Offset = R
2
1
+R
2
a). Using resistor divider.
V
0
R
L
1
REF200
100
μ
A
V
+
V
+
Gain Set by R
L
Output Offset = (100
μ
A)(R
L
)
(independent of V+)
b). Using current source.
INA138
3
4
INA138
3
4
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| INA138_11 | 制造商:BB 制造商全稱:BB 功能描述:High-Side Measurement CURRENT SHUNT MONITOR |
| INA138NA | 制造商:Texas Instruments 功能描述:IC AMP DIFF SMD SOT-23-5 138 |
| INA138NA/250 | 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 Hi-Sd Msmnt Current Shunt Mntr Crnt Otp RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Current Regulators 電源電壓-最大:48 V 電源電壓-最小:5.5 V 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel |
| INA138NA/250 | 制造商:Texas Instruments 功能描述:IC CURRENT SHUNT MONITOR |
| INA138NA/250 | 制造商:Texas Instruments 功能描述:Current Shunt Monitor IC |
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