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参数资料
| 型号： | LT6105HDCB#TRMPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 模拟信号调理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, PDSO6 |
| 封装： | 2 X 3 MM, LEAD FREE, PLASTIC, DFN-6 |
| 文件页数： | 4/20页 |
| 文件大小： | 382K |
| 代理商： | LT6105HDCB#TRMPBF |
LT6105
12
6105fa
The LT6105 extended input range current sense am-
plier (see Figure 1) provides accurate unidirectional
monitoring of current through a user-selected sense resis-
tor. The LT6105 is fully specied over a –0.3V to 44V input
common mode range. A high PSRR V+ supply (2.85V to
36V) powers the current sense amplier. The input sense
voltage is level shifted from the sensed power supply to
the ground reference and amplied by a user-selected gain
to the output. The output voltage is directly proportional
to the current owing through the sense resistor.
THEORY OF OPERATION
(Refer to Figure 1)
Case 1: High Input Voltage (1.6V < V–IN < 44V)
Current from the source at VS+ ows through RSENSE to
the load at VS–, creating a sense voltage, VSENSE. Inputs
VS+ and VS– apply the sense voltage to RIN2. The opposite
ends of resistors RIN1 and RIN2 are forced to be at equal
potentials by the voltage gain of amplier A2. Thus, the
current through RIN2 is VSENSE/RIN2. The current through
RIN2 is forced to ow through transistor Q1 and into
ROUT, creating an output voltage, VOUT. Under this input
operation range, amplier A1 is kept off. The base current
of Q1 has been compensated for and will not contribute
to output error. The current from RIN2 owing through
resistor ROUT gives an output voltage of VOUT = VSENSE
ROUT/RIN2, producing a gain voltage of AV = VOUT/VSENSE
= ROUT/RIN2.
Case 2: Low Input Voltage (0V < V–IN < 1.6V)
Current from the source at VS+ ows through RSENSE to
the load at VS–, creating a sense voltage, VSENSE. Inputs
VS+ and VS– apply the sense voltage to RIN1. The opposite
ends of resistors RIN1 and RIN2 are forced to be at equal
potentials by the voltage gain of amplier A1. Thus, the
collector current of Q3 will ow out of the –IN pin through
RIN1. Q2 mirrors this current VSENSE/RIN1 to ROUT, creat-
ing an output voltage, VOUT. Under this input operation
range, amplier A2 is kept off. This current VSENSE/RIN1
owing through resistor ROUT gives an output voltage of
VOUT = VSENSE ROUT/RIN1, producing a gain voltage of
AV = VOUT/VSENSE = ROUT/RIN1.
APPLICATIONS INFORMATION
Selection of External Current Sense Resistor
External RSENSE resistor selection is a delicate trade-off
between power dissipation in the resistor and current
measurement accuracy. For high current applications, the
user may want to minimize the sense voltage to minimize
the power dissipation in the sense resistor.
The system load current will cause both heat and voltage
loss in RSENSE. As a result, the sense resistor should be as
small as possible while still providing the input dynamic
range required by the measurement. Note that input dy-
namic range is the difference between the maximum input
signal and the minimum accurately reproduced signal,
and is limited primarily by input DC offset voltage of the
internal amplier of the LT6105.
The sense resistor value will be set from the minimum
signal current that can be accurately resolved by this sense
amp. As an example, the LT6105 has a typical input offset
of 100μV. If the minimum current is 20mA, a sense resistor
of 5m
Ω will set VSENSE to 100μV, which is the same value
as the input offset. A larger sense resistor will reduce the
error due to offset by increasing the sense voltage for
a given load current, but it will limit the maximum peak
current for a given application.
For a peak current of 2A and a maximum VSENSE of 80mV,
RSENSE should not be more than 40mΩ. The input offset
causes an error equivalent to only 2.5mA of load current.
Peak dissipation is 160mW. If a 20m
Ω sense resistor is
employed, then the effective current error is 5mA, while
the peak sense voltage is reduced to 40mV at 2A, dis-
sipating only 80mW.
The LT6105’s low input offset voltage of 100μV allows for
high resolution while limiting the maximum sense voltages.
Coupled with full scale sense voltage as large as 1V for
RIN= 1k, it can achieve 80dB of dynamic range.
Sense Resistor Connection
Kelvin connection of the LT6105’s input resistors to the
sense resistor should be implemented to provide the high-
est accuracy in high current applications. Solder connec-
tions and PC board interconnect resistance (approximately
0.5m
Ω per square for 1oz copper) can be a large error
in high current systems. A 5A application might choose
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT6105HDCB-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Precision, Extended Input Range Current Sense Amplifi er |
| LT6105HMS8#PBF | 功能描述:IC AMP R-R CURRENT SENSE 8-MSOP RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1,000 系列:- 放大器类型:电压反馈 电路数:4 输出类型:满摆幅 转换速率:33 V/µs 增益带宽积:20MHz -3db带宽:30MHz 电流 - 输入偏压:2nA 电压 - 输入偏移:3000µV 电流 - 电源:2.5mA 电流 - 输出 / 通道:30mA 电压 - 电源，单路/双路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SOIC 包装:带卷 (TR) |
| LT6105HMS8#TRPBF | 功能描述:IC AMP R-R CURRENT SENSE 8-MSOP RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:1,000 系列:- 放大器类型:电压反馈 电路数:4 输出类型:满摆幅 转换速率:33 V/µs 增益带宽积:20MHz -3db带宽:30MHz 电流 - 输入偏压:2nA 电压 - 输入偏移:3000µV 电流 - 电源:2.5mA 电流 - 输出 / 通道:30mA 电压 - 电源，单路/双路(±):4.5 V ~ 16.5 V，±2.25 V ~ 8.25 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SOIC 包装:带卷 (TR) |
| LT6105HMS8-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Precision, Extended Input Range Current Sense Amplifi er |
| LT6105HMS8-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Precision, Extended Input Range Current Sense Amplifi er |
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