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参数资料
| 型号： | LTC2990CMS#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO10 |
| 封装： | PLASTIC, MSOP-10 |
| 文件页数： | 2/24页 |
| 文件大小： | 236K |
| 代理商： | LTC2990CMS#TR |
LTC2990
10
2990fa
APPLICATIONS INFORMATION
unsigned number and the measured Kelvin (unsigned)
temperature represented as a 16-bit number, yields a
32-bit unsigned result. To scale this number back to a
13-bit temperature (9-bit integer part, and a 4-bit frac-
tional part), divide the number by 215 per Equation (5).
Similarly, Celsius coded temperature values can be scaled
using 16-bit fixed-point arithmetic, using Equation (6).
In both cases, the scaled result will have a 9-bit integer
(d[12:4]) and the 4LSBs (d[3:0]) representing the 4-bit
fractional part. To convert the corrected result to decimal,
divide the final result by 24 or 16, as you would the reg-
ister contents. If ideality factor scaling is implemented
in the target application, it is beneficial to configure the
LTC2990 for Kelvin coded results to limit the number of
math operations required in the target processor.
TK_COMP =
Unsigned
(
) ηCAL
ηACT
215
TK_MEAS
215
(5)
TC_COMP =
Unsigned
(
) ηCAL
ηACT
215
TC_MEAS +273.152
4
(
)
215
– 273.15 24
(6)
Sampling Currents
Single-ended voltage measurements are directly sampled
by the internal ADC. The average ADC input current is a
function of the input applied voltage as follows:
IIN(AVG) = (VIN – 1.49V) 0.17[A/V]
Inputs with source resistance less than 200Ω will yield
full-scale gain errors due to source impedance of <1/2LSB
for 14-bit conversions. The nominal conversion time is
1.5ms for single-ended conversions.
Current Measurements
The LTC2990 has the ability to perform 14-bit current
measurements with the addition of a current sense resis-
tor (see Figure 3).
In order to achieve accurate current sensing a few de-
tails must be considered. Differential voltage or current
measurements are directly sampled by the internal ADC.
The average ADC input current for each leg of the differ-
ential input signal during a conversion is (VIN – 1.49V)
0.34[A/V]. The maximum source impedance to yield
14-bit results with, 1/2LSB full-scale error is ~50Ω. In
order to achieve high accuracy 4-point, or Kelvin con-
nected measurements of the sense resistor differential
voltage are necessary.
In the case of current measurements, the external sense
resistor is typically small, and determined by the full-scale
input voltage of the LTC2990. The full-scale differential
voltage is 0.300V. The external sense resistance is then a
functionofthemaximummeasurablecurrent,orREXT_MAX
= 0.300V/IMAX. For example, if you wanted to measure a
current range of ±5A, the external shunt resistance would
equal 0.300V/5mA = 60mΩ.
Thereexistsawaytoimprovethesenseresistor’sprecision
usingtheLTC2990.TheLTC2990measuresbothdifferential
voltage and remote temperature. It is therefore, possible
to compensate for the absolute resistance tolerance of the
sense resistor and the temperature coefficient of the sense
resistor in software. The resistance would be measured
by running a calibrated test current through the discrete
resistor. The LTC2990 would measure both the differential
voltage across this resistor and the resistor temperature.
From this measurement, RO and TO in the equation be-
low would be known. Using the two equations, the host
microprocessor could compensate for both the absolute
tolerance and the TCR.
RT = RO [1 + α(T – TO)]
where:
α = +3930 ppm/°C for copper trace
α = ±2 to ~+200ppm/°C for discrete R
(7)
I = (V1 – V2)/RT
(8)
Figure 3. Simplified Current Sense Schematic
V1
V2
LTC2990
0V – VCC
RSENSE
ILOAD
2990 F03
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC2990IMS | 制造商:Linear Technology 功能描述:Temperature, Voltage and Current Monitor 10-Pin MSOP |
| LTC2990IMS#PBF | 功能描述:IC TEMP/VOLT/CUR MONITOR 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热管理 系列:- 标准包装:2,500 系列:SilentSense™ 功能:温度监控系统（传感器） 传感器类型:内部和外部 感应温度:-55°C ~ 125°C，外部传感器 精确度:±2°C 本地（最大），±3°C 远程（最大） 拓扑:ADC（三角积分型），比较器，寄存器库 输出类型:I²C?/SMBus? 输出警报:是 输出风扇:是 电源电压:2.7 V ~ 5.5 V 工作温度:-55°C ~ 125°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MSOP 包装:带卷 (TR) 其它名称:MIC284-2BMMTRMIC284-2BMMTR-ND |
| LTC2990IMS#PBF | 制造商:Linear Technology 功能描述:IC TEMP SENS 14BIT ? MSOP-10 制造商:Linear Technology 功能描述:IC, TEMP SENS, 14BIT, 2C, MSOP-10 |
| LTC2990IMS#TRPBF | 功能描述:IC TEMP/VOLT/CUR MONITOR 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热管理 系列:- 标准包装:2,500 系列:SilentSense™ 功能:温度监控系统（传感器） 传感器类型:内部和外部 感应温度:-55°C ~ 125°C，外部传感器 精确度:±2°C 本地（最大），±3°C 远程（最大） 拓扑:ADC（三角积分型），比较器，寄存器库 输出类型:I²C?/SMBus? 输出警报:是 输出风扇:是 电源电压:2.7 V ~ 5.5 V 工作温度:-55°C ~ 125°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MSOP 包装:带卷 (TR) 其它名称:MIC284-2BMMTRMIC284-2BMMTR-ND |
| LTC2991CMS#PBF | 功能描述:IC MONITOR OCTAL 16-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热管理 系列:- 标准包装:3,000 系列:- 功能:温度开关 传感器类型:内部 感应温度:85°C 分界点 精确度:±6°C（最小值） 拓扑:ADC（三角积分型），比较器，寄存器库 输出类型:开路漏极 输出警报:是 输出风扇:是 电源电压:2.7 V ~ 5.5 V 工作温度:-55°C ~ 125°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:带卷 (TR) 其它名称:ADT6501SRJZP085RL7-ND |
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