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参数资料
| 型号： | LTC2990CMS |
| 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： | 24/24页 |
| 文件大小： | 236K |
| 代理商： | LTC2990CMS |
LTC2990
9
2990fa
APPLICATIONS INFORMATION
Figure 2. Recommended PCB Layout
V1
V2
V3
V4
VCC
ADR1
ADR0
SCL
SDA
LTC2990
2990 F02
GND SHIELD
TRACE
NPN SENSOR
470pF
0.1F
GND
The change in sensor voltage per degree temperature
change is 275V/°C, so environmental noise must be kept
to a minimum. Recommended shielding and PCB trace
considerations are illustrated in Figure 2.
The diode equation:
VBE = η
k T
q
ln
IC
IS
(1)
can be solved for T, where T is Kelvin degrees, IS is a
process dependent factor on the order of 1E-13,
η is the
diode ideality factor, k is Boltzmann’s constant and q is
the electron charge.
T
=
VBE q
η k In
IC
IS
(2)
The LTC2990 makes differential measurements of diode
voltage to calculate temperature. Proprietary techniques
allow for cancellation of error due to series resistance.
the diode sensor can be considered a temperature scaling
factor.Thetemperatureerrorfora1%accurateidealityfac-
tor error is 1% of the Kelvin temperature. Thus, at 25°C, or
298°K, a +1% accurate ideality factor error yields a +2.98
degree error. At 85°C or 358°K, a +1% error yields a 3.6
degree error. It is possible to scale the measured Kelvin
or Celsius temperature measured using the LTC2990 with
a sensor ideality factor other than 1.004, to the correct
value. The scaling Equations (3) and (4) are simple, and
can be implemented with sufficient precision using 16-bit
fixed-point math in a microprocessor or microcontroller.
Factory Ideality Calibration Value:
ηCAL = 1.004
Actual Sensor Ideality Value:
ηACT
Compensated Kelvin Temperature:
TK _COMP =
ηCAL
ηACT
TK _MEAS
(3)
Compensated Celsius Temperature
TC_COMP =
ηCAL
ηACT
TC_MEAS + 273
(
)
– 273
(4)
A 16-bit unsigned number is capable of representing the
ratio
ηACT/ηCAL in a range of 0.00003 to 1.99997, by
multiplying the fractional ratio by 215. The range of scal-
ing encompasses every conceivable target sensor value.
The ideality factor scaling granularity yields a worst-case
temperatureerrorof0.01°at125°C.Multiplyingthis16-bit
Ideality Factor Scaling
The LTC2990 is factory calibrated for an ideality factor of
1.004, which is typical of the popular MMBT3904 NPN
transistor. The semiconductor purity and wafer-level pro-
cessing limits device-to-device variation, making these
devices interchangeable (typically <0.5C) for no additional
cost. Several manufacturers supply suitable transistors,
some recommended sources are listed in Table 1. Discrete
2-terminal diodes are not recommended as temperature
sensors. While an ideality factor value of 1.004 is typical of
target sensors, small deviations can yield significant tem-
perature errors. Contact LTC Marketing for parts trimmed
to ideality factors other than 1.004. The ideality factor of
Table 1. Recommended Transistors to Be Used as Temperature
Sensors
MANUFACTURER
PART NUMBER
PACKAGE
Fairchild Semiconductor
MMBT3904
FMMT3904
SOT-23
Central Semiconductor
CMPT3904
CET3904E
SOT-23
SOT883L
Diodes, Inc.
MMBT3904
SOT-23
On Semiconductor
MMBT3904LT1
SOT-23
NXP
MMBT3904
SOT-23
Infineon
MMBT3904
SOT-23
Rohm
UMT3904
SC-70
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC2990CMS#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: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 |
| LTC2990CMS#PBF | 制造商:Linear Technology 功能描述:IC SUPERVISORY 1.1mA 5.5V MSOP10 制造商:Linear Technology 功能描述:IC, SUPERVISORY, 1.1mA, 5.5V, MSOP10 |
| LTC2990CMS#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 |
| 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 |
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