参数资料
型号: MAX9934TALT+T
厂商: Maxim Integrated Products
文件页数: 8/19页
文件大小: 0K
描述: IC AMP CURR SENSE LV 6UDFN
标准包装: 2,500
放大器类型: 电流检测
电路数: 1
-3db带宽: 1.5kHz
电流 - 输入偏压: 35µA
电压 - 输入偏移: 10µV
电流 - 电源: 120µA
电压 - 电源,单路/双路(±): 2.5 V ~ 3.6 V
工作温度: -40°C ~ 125°C
安装类型: 表面贴装
封装/外壳: 6-WFBGA,CSPBGA
供应商设备封装: 6-uCSP(1.57x1.16)
包装: 带卷 (TR)
MAX9934
High-Precision, Low-Voltage, Current-Sense Amplifier
with Current Output and Chip Select for Multiplexing
16
Maxim Integrated
Effect of Input-Bias Currents
The MAX9934 has extremely low CMOS input-bias cur-
rents at both RS+ and RS- (0.1nA) when the input com-
mon-mode voltage is less than the supply voltage.
When the input common-mode voltage becomes higher
than the supply voltage, it draws the input stage operat-
ing current from RS-, 35A (typ). RS+ maintains its
CMOS input characteristics.
Low-input-bias currents are extremely useful in design
of input filters for current-sense amplifiers. Input differ-
ential filters are sometimes required to average out
rapidly varying load currents. An example of such load
currents are those consumed by a processor, or
switching power supply. Large bias and offset currents
can interact with resistors used in these external filters
to generate large input offset voltages and gain errors.
For more detailed information, see Application Note
AN3888:
Performance of Current-Sense Amplifiers with
Input Series Resistors.
Due to the low-input-bias currents, resistors as large as
10k
can be easily used without impact on error speci-
fications with the MAX9934. For applications where the
input common-mode voltage is below VCC, a balanced
differential filter can be used. For applications where
the input common-mode voltage extends above VCC,
use a one-sided filter with a capacitor between RS+
and RS-, and a filter resistor in series with RS+ to main-
tain the excellent performance of the MAX9934. See
Figure 7.
PCB Layout
For applications where the input common-mode voltage
extends above VCC, trace resistance between RSENSE
and RS- influences the effective VOS error due to the
voltage drop developed across the trace resistance by
the 35A input bias current at RS-.
Monitoring Very Low Currents
The accuracy of the MAX9934 leads to a wide dynamic
range. This applies to both unidirectional mode and
bidirectional mode. This is made possible in the unidi-
rectional mode because the output maintains gain
accuracy below 1mV as shown in the VOUT vs. VSENSE
(VOUT < 5mV) graph in the Typical Operating Char-
acteristics. Extending the useful output below 1mV
makes it possible for the MAX9934 to accurately moni-
tor very low currents.
Use as Precision
Instrumentation Amplifier
When the input common-mode voltage is below VCC,
the input bias current of the RS- input drops to the
10pA range, the same range as the RS+ input. This
low-input-bias current in combination with the rail-to-rail
common-mode input range, the extremely high com-
mon-mode rejection, and low VOS of the MAX9934
make it ideally suited for use as a precision instrumen-
tation amplifier. In addition, the MAX9934 is stable into
an infinite capacitive load, allowing filtering flexibility.
Figure 8 shows the MAX9934 in a multiplexed arrange-
ment of strain-gauge amplifiers.
BUCK
CONTROLLER
RS+
RS-
MAX9934
ASIC
Figure 7. One-Sided Input Filter
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