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| 型号： | MAX9934EVKIT+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/19页 |
| 文件大小： | 0K |
| 描述： | KIT EVAL FOR MAX9934 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 每 IC 通道数： | 1 - 单 |
| 放大器类型： | 电流检测 |
| 输出类型： | 单端 |
| 工作温度： | -40°C ~ 125°C |
| 电流供应（主 IC）： | 120µA |
| 电压 - 电源，单路/双路(±)： | 2.5 V ~ 3.6 V |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MAX9934 |
MAX9934
High-Precision, Low-Voltage, Current-Sense Amplifier
with Current Output and Chip Select for Multiplexing
15
Maxim Integrated
Three components are to be selected to optimize the
current-sense system: RSENSE, ROUT, and the
MAX9934 gain option (GM = 25A/mV or 5A/mV).
Tables 1 and 2 are gain tables for unidirectional and
bidirectional operation, respectively. They offer a few
examples for both MAX9934 options having an output
range of 3.1V unidirectional and ±1.65V bidirectional.
Note that the output current of the MAX9934 adds to its
quiescent current. This can be calculated as follows:
IOUT,MAX = VOUT,MAX/ROUT
When selecting RSENSE, consider the expected magni-
tude of ILOAD and the required VSENSE to manage
power dissipation in RSENSE:
RSENSE = VSENSE,MAX/ILOAD,MAX
RSENSE is typically a low-value resistor specifically
designed for current-sense applications.
Finally, in selecting the appropriate MAX9934 gain option
(GM), consider both the required VSENSE and IOUT:
GM = IOUT,MAX/VSENSE,MAX
Once all three component values have been selected in
the current-sense application, the system performance
is represented by:
VSENSE = RSENSE x ILOAD
and
VOUT = VSENSE x GM x ROUT
Accuracy
In a first-order analysis of accuracy there are two
MAX9934 specifications that contribute to output error,
input offset (VOS) and gain error (GE). The MAX9934 has
a maximum VOS of 10V and a maximum GE of 0.25%.
Note that the tolerance and temperature coefficient of
the chosen resistors directly affect the precision of any
measurement system.
Efficiency and Power Dissipation
At high-current levels, the I2R losses in RSENSE can be
significant. Take this into consideration when choosing
the resistor value and its power dissipation (wattage)
rating. Also, the sense resistor’s value drifts if it is
allowed to self-heat excessively. The precision VOS of
the MAX9934 allows the use of a small sense resistor to
reduce power dissipation and eliminate hot spots.
Kelvin Contacts
Due to the high currents that flow through RSENSE, take
care to prevent trace resistance in the load current path
from causing errors in the sense voltage. Use a four ter-
minal current-sense resistor or Kelvin contacts (force
and sense) PCB layout techniques.
Interfacing the MAX9934 to SAR ADCs
Since the MAX9934 is essentially a high-output imped-
ance current-source, its output termination resistor,
ROUT, acts like a source impedance when driving an
ADC channel. Most successive approximation register
(SAR) architecture ADCs specify a maximum source
resistance to avoid compromising the accuracy of their
readings. Choose the output termination resistor ROUT
such that it is less than that required by the ADC speci-
fication (10k
or less). If the ROUT is larger than the
source resistance specified, the ADC internal sampling
capacitor can momentarily load the amplifier output
and cause a drop in the voltage reading.
If ROUT is larger than the source resistance specified,
consider using a ceramic capacitor from ADC input to
GND. This input capacitor supplies momentary charge
to the internal ADC sampling capacitor, helping hold
VOUT constant to within ±1/2 LSB during the acquisition
period. Use of this capacitor reduces the noise in the
output signal to improve sensitivity of measurement.
PART
VSENSE
(mV)
OUTPUT
CURRENT
(A)
ROUT
(k
)
GAIN
(V/V)
12.4
310
10
250
MAX9934T
24.8
620
5
125
62
310
10
50
MAX9934F
75
375
8
40
Table 1. Unidirectional Gain Table*
*
All calculations were made with VCC = 3.3V and VOUT(MAX) =
VCC - VOH = 3.1V.
PART
VSENSE
(mV)
OUTPUT
CURRENT
(A)
ROUT
(k
)
GAIN (V/V)
±5.8
±145
10
250
±11.6
±290
5
125
MAX9934T
±24
±600
2.4
60
±29
±145
10
50
±58
±290
5
25
MAX9934F
±72
±360
4
20
Table 2. Bidirectional Gain Table*
*
All calculations were made with VCC = 3.3V, VOUT(MAX) = VCC -
VOH = 3.1V, VOUT(MIN) = VOL, and OUT connected to an exter-
nal reference voltage of VREF = 1.65V through ROUT.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX9934EVKIT+ | 功能描述:放大器 IC 开发工具 MAX9934 Eval Kit RoHS:否 制造商:International Rectifier 产品:Demonstration Boards 类型:Power Amplifiers 工具用于评估:IR4302 工作电源电压:13 V to 23 V |
| MAX9934FALT+T | 功能描述:电流灵敏放大器 Precision Current Sense Amp RoHS:否 制造商:Texas Instruments 通道数量: 共模抑制比（最小值）:110 dB 输入补偿电压:80 uV 电源电压-最大:5.5 V 电源电压-最小:2.7 V 电源电流:350 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-16 封装:Reel |
| MAX9934FART+T | 功能描述:电流灵敏放大器 Precision Current Sense Amp RoHS:否 制造商:Texas Instruments 通道数量: 共模抑制比（最小值）:110 dB 输入补偿电压:80 uV 电源电压-最大:5.5 V 电源电压-最小:2.7 V 电源电流:350 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-16 封装:Reel |
| MAX9934FART+TG0Y | 功能描述:特殊用途放大器 RoHS:否 制造商:Texas Instruments 通道数量:Single 共模抑制比（最小值）: 输入补偿电压: 工作电源电压:3 V to 5.5 V 电源电流:5 mA 最大功率耗散: 最大工作温度:+ 70 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:QFN-20 封装:Reel |
| MAX9934FAUA+ | 功能描述:电流灵敏放大器 Precision Current Sense Amp RoHS:否 制造商:Texas Instruments 通道数量: 共模抑制比（最小值）:110 dB 输入补偿电压:80 uV 电源电压-最大:5.5 V 电源电压-最小:2.7 V 电源电流:350 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-16 封装:Reel |
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