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| 型号： | TC648EOA |
| 元件分类： | 运动控制电子 |
| 英文描述： | BRUSHLESS DC MOTOR CONTROLLER, PDSO8 |
| 封装： | 0.150 INCH, PLASTIC, SOIC-8 |
| 文件页数： | 2/28页 |
| 文件大小： | 602K |
| 代理商： | TC648EOA |
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TC648
DS21448C-page 10
2002 Microchip Technology Inc.
5.1
Temperature Sensor Design
The temperature signal connected to VIN 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:
Temperature Sensing
Circuit.
RT1 is a conventional NTC thermistor and R1 and R2
are standard resistors. The supply voltage (VDD) is
RT1 and R1. For convenience, the parallel combination
of RT1 and R1 will be referred to as RTEMP. 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, R1 is
used to linearize the thermistor temperature response
and R2 is used to produce a positive temperature
coefficient at the VIN node. As an added benefit, this
configuration produces an output voltage delta of 1.4V,
which is well within the range of the VC(SPAN)
specification of the TC648. A 100 k
NTC thermistor is
selected for this application in order to keep IDIV to a
minimum.
For the voltage range at VIN 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, R1 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, R2 is adjusted according to the following
equations:
EQUATION
These two equations facilitate solving for the two
unknown variables, R1 and R2. 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 VAS and designing the temperature sensor
network such that VIN 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 VIN values of 1.25V and 2.65V, typical.
Minimum system temperature (TMIN) 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
TMIN and at speeds proportional to the measured
FIGURE 5-3:
Minimum Fan Speed Mode
Operation.
Temperature sensor design consists of a two-point
calculation: one at TMIN and one at TMAX. At TMIN, the
ohmic value of the thermistor must be much higher
than that of R1 so that minimum speed is determined
primarily by the values of R1 and R2. At TMAX, the
ohmic value of the thermistor must result in a VIN of
2.65V nominal. The design procedure consists of ini-
tially choosing R1 to be 10 times smaller than the ther-
R2 = 23.2 k
R1 = 100 k
IDIV
VIN
VDD
NTC Thermistor
100 k
@25C
RT1
VDD x R2
RTEMP (T1) + R2
= V(T1)
RTEMP (T2) + R2
= V(T2)
VDD x R2
Where T1 and T2 are the chosen temperatures and
RTEMP is the parallel combination of the thermistor
and R1.
Fan Speed
100%
Minimum
Speed
0%
TMIN
TMAX
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相关代理商/技术参数 |
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| TC648EOA713 | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
| TC648EPA | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert |
| TC648EUA | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
| TC648EUA713 | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
| TC648VOA | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & Over-T Alert RoHS:否 制造商:STMicroelectronics 产品:Stepper Motor Controllers / Drivers 类型:2 Phase Stepper Motor Driver 工作电源电压:8 V to 45 V 电源电流:0.5 mA 工作温度:- 25 C to + 125 C 安装风格:SMD/SMT 封装 / 箱体:HTSSOP-28 封装:Tube |
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