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參數(shù)資料
| 型號： | TC648E |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert |
| 中文描述： | 與自動風(fēng)扇轉(zhuǎn)速控制關(guān)斷和過溫警報 |
| 文件頁數(shù)： | 10/28頁 |
| 文件大?。?/td> | 602K |
| 代理商： | TC648E |
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TC648
DS21448C-page 10
2002 Microchip Technology Inc.
5.1
Temperature Sensor Design
The temperature signal connected to V
IN
must output a
voltage in the range of 1.25V to 2.65V (typical) for 0%
to 100% of the temperature range of interest. The
circuit in Figure 5-2 illustrates a convenient way to pro-
vide this signal using a temperature dependent voltage
divider circuit.
FIGURE 5-2:
Circuit.
Temperature Sensing
RT
1
is a conventional NTC thermistor and R
1
and R
2
are standard resistors. The supply voltage (V
DD
) is
divided between R
2
and the parallel combination of
RT
1
and R
1
. For convenience, the parallel combination
of RT
1
and R
1
will be referred to as R
TEMP
. The resis-
tance of the thermistor at various temperatures is
obtained from the manufacturer’s specifications. Ther-
mistors are often referred to in terms of their resistance
at 25°C.
Generally, the thermistor shown in Figure 5-2 is a non-
linear device with a negative temperature coefficient
(also called an NTC thermistor). In Figure 5-2, R
1
is
used to linearize the thermistor temperature response
and R
2
is used to produce a positive temperature
coefficient at the V
IN
node. As an added benefit, this
configuration produces an output voltage delta of 1.4V,
which is well within the range of the V
C(SPAN)
specification of the TC648. A 100 k
NTC thermistor is
selected for this application in order to keep I
DIV
to a
minimum.
For the voltage range at V
IN
to be equal to 1.25V to
2.65V, the temperature range of this configuration is
0°C to 50°C. If a different temperature range is required
from this circuit, R
1
should be chosen to equal the
resistance value of the thermistor at the center of this
new temperature range. It is suggested that a maxi-
mum temperature range of 50°C be used with this cir-
cuit due to thermistor linearity limitations. With this
change, R
2
is adjusted according to the following
equations:
EQUATION
These two equations facilitate solving for the two
unknown variables, R
1
and R
2
. More information about
thermistors may be obtained from AN679,
“Tempera-
ture Sensing Technologies”
, and AN685,
“Thermistors
in Single Supply Temperature Sensing Circuits”
, which
can be downloaded from Microchip's web site at
www.microchip.com.
5.2
Minimum Speed Mode
The TC648 is configured for minimum speed mode by
grounding V
AS
and designing the temperature sensor
network such that V
IN
operates the fan at relatively con-
stant, minimum speed when the thermistor is at
minimum temperature.
Figure 5-3 shows operation in
minimum speed mode. The 0% and 100% fan speeds
correspond to V
IN
values of 1.25V and 2.65V, typical.
Minimum system temperature (T
MIN
) is defined as the
lowest measured temperature at which proportional fan
speed control is required by the system. The fan
operates at minimum speed for all temperatures below
T
MIN
and at speeds proportional to the measured
temperature between T
MIN
and T
MAX
.
FIGURE 5-3:
Operation.
Minimum Fan Speed Mode
Temperature sensor design consists of a two-point
calculation: one at T
MIN
and one at T
MAX
. At T
MIN
, the
ohmic value of the thermistor must be much higher
than that of R
1
so that minimum speed is determined
primarily by the values of R
1
and R
2
. At T
MAX
, the
ohmic value of the thermistor must result in a V
IN
of
2.65V nominal. The design procedure consists of ini-
tially choosing R
1
to be 10 times smaller than the ther-
R
2
= 23.2 k
R
1
= 100 k
IDIV
VIN
VDD
NTC Thermistor
100 k
@25C
RT
1
V
DD
x R
2
R
TEMP
(T
1
) + R
2
= V(T
1
)
R
TEMP
(T
2
) + R
2
= V(T
2
)
V
DD
x R
2
Where T
1
and T
2
are the chosen temperatures and
R
TEMP
is the parallel combination of the thermistor
and R
1
.
Fan Speed
100%
Minimum
Speed
0%
T
MIN
T
MAX
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| TC648VPA | Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert |
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| TC649VOA | CAPACITOR, CLASS Y2 15NFCAPACITOR, CLASS Y2 15NF; Capacitance:15nF; Voltage rating, AC:250V; Voltage rating, DC:2500V; Capacitor dielectric type:Polypropylene; Series:B81122; Tolerance, +:20%; Tolerance, -:20%; Temp, op. |
| TC649VPA | CAPACITOR, CLASS Y2 150NFCAPACITOR, CLASS Y2 150NF; Capacitance:150nF; Voltage rating, AC:250V; Voltage rating, DC:2500V; Capacitor dielectric type:Polypropylene; Series:B81122; Tolerance, +:20%; Tolerance, -:20%; Temp, op. |
| TC649VUA | CAPACITOR, CLASS Y2 22NFCAPACITOR, CLASS Y2 22NF; Capacitance:22nF; Voltage rating, AC:250V; Voltage rating, DC:2500V; Capacitor dielectric type:Polypropylene; Series:B81122; Tolerance, +:20%; Tolerance, -:20%; Temp, op. |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TC648EOA | 功能描述:馬達(dá)/運動/點火控制器和驅(qū)動器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC648EOA713 | 功能描述:馬達(dá)/運動/點火控制器和驅(qū)動器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC648EPA | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert |
| TC648EUA | 功能描述:馬達(dá)/運動/點火控制器和驅(qū)動器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC648EUA713 | 功能描述:馬達(dá)/運動/點火控制器和驅(qū)動器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類型:2 Phase Stepper Motor Driver 工作電源電壓:8 V to 45 V 電源電流:0.5 mA 工作溫度:- 25 C to + 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
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