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参数资料
| 型号： | TC647VOART |
| 元件分类： | 运动控制电子 |
| 英文描述： | BRUSHLESS DC MOTOR CONTROLLER, PDSO8 |
| 封装： | SOIC-8 |
| 文件页数： | 13/15页 |
| 文件大小： | 117K |
| 代理商： | TC647VOART |
7
TC647-2
12/05/00
TC647
PWM Fan Speed Controller with FanSense*
2001 Microchip Technology Inc.
DS21447A
APPLICATIONS INFORMATION
Designing with the TC647 involves the following:
(1) The temp sensor network must be configured to
deliver 1.25V to 2.65V on VIN for 0% to 100% of the
temperature range to be regulated.
(2) The minimum fan speed (VMIN) must be set.
(3) The output drive transistor and associated circuitry
must be selected.
(4) The Sense Network, RSENSE and CSENSE, must be
designed for maximum efficiency while delivering
adequate signal amplitude.
(5) If Shutdown capability is desired, the drive require-
ments of the external signal or circuit must be
considered.
The TC642DEMO demonstration and prototyping
board and the TC642EV Evaluation Kit provide working
examples of TC647 circuits and prototyping aids.
The
TC642DEMO is a printed circuit board optimized for small
size and ease of inclusion into system prototypes. The
TC642EV is a larger board intended for benchtop develop-
ment and analysis. At the very least, anyone contemplating
a design using the TC647 should consult the documentation
for both TC642EV and TC642DEMO.
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 of
Figure 4 is a convenient way to provide this signal.
Figure 4 illustrates a simple temperature dependent
voltage divider circuit. T1 is a conventional NTC thermistor,
and R1 and R2 are standard resistors. The supply voltage,
VDD, is divided between R2 and the parallel combination of
T1 and R1. (For convenience, the parallel combination of
T1 and R1 will be referred to as RTEMP.) The resistance of
the thermistor at various temperatures is obtained from the
manufacturer’s specifications. Thermistors are often re-
ferred to in terms of their resistance at 25
°C. A thermistor
with a 25
°C resistance on the order of 100k will result in
reasonable values for R1, R2, and IDIV. In order to determine
R1 and R2, we must specify the fan duty-cycle, i.e. VIN, at
any two temperatures. Equipped with these two points on
the system’s operating curve and the thermistor data, we
can write the defining equations:
VDD x R2
RTEMP (t1) + R2
= V(t1)
VDD x R2
RTEMP (t2) + R2
= V(t2)
Equaton 1.
Where
t1 and t2 are the chosen temperatures and
RTEMP is the parallel combination of the thermistor and R1.
These two equations permit solving for the two unknown
variables, R1 and R2. Note that resistor R1 is not absolutely
necessary, but it helps to linearize the response of the
network.
Minimum Fan Speed
A voltage divider on VMIN sets the minimum PWM duty
cycle and, thus, the minimum fan speed. As with the VIN
input, 1.25V to 2.65V corresponds to 0% to 100% duty
cycle. Assuming that fan speed is linearly related to duty-
cycle, the minimum speed voltage is given by the equation:
VMIN = Minimum Speed x (1.4V) + 1.25V
Full Speed
Equation 2.
For example, if 2500 RPM equates to 100% fan speed,
and a minimum speed of 1000 RPM is desired, then the VMIN
voltage is:
VMIN = 1000 x (1.4V) + 1.25V = 1.81V
2500
Equation 3.
The VMIN voltage may be set using a simple resistor
divider as shown in Figure 5. Per the
Electrical Characteris-
tics, the leakage current at the VMIN pin is no more than
1
A. It would be very conservative to design for a divider
current, IDIV, of 100
A. If VDD = 5.0V then…
IDIV = 1e–4 A =
5.0V , therefore
R1 + R2
R1 + R2 = 5.0V = 50,000
= 50k
1e–4 A
Equation 4.
We can further specify R1 and R2 by the condition that
the divider voltage is equal to our desired VMIN. This yields
the following equation:
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC647VOATR | 功能描述:马达/运动/点火控制器和驱动器 w/Fault Dtct 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 |
| TC647VPA | 功能描述:马达/运动/点火控制器和驱动器 w/Fault Dtct 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 |
| TC647VUA | 功能描述:马达/运动/点火控制器和驱动器 w/Fault Dtct 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 |
| TC647VUATR | 功能描述:马达/运动/点火控制器和驱动器 w/Fault Dtct 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 |
| TC648 | 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 |
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