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| 型号： | TC649BEUATR |
| 元件分类： | 运动控制电子 |
| 英文描述： | BRUSHLESS DC MOTOR CONTROLLER, PDSO8 |
| 封装： | PLASTIC, MSOP-8 |
| 文件页数： | 4/36页 |
| 文件大小： | 704K |
| 代理商： | TC649BEUATR |
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TC646B/TC648B/TC649B
DS21755B-page 12
2003 Microchip Technology Inc.
FIGURE 4-2:
PWM Fan Drive.
By modulating the voltage applied to the gate of the
MOSFET (QDRIVE), the voltage that is applied to the
fan is also modulated. When the VOUT pulse is high, the
gate of the MOSFET is turned on, pulling the voltage at
the drain of QDRIVE to zero volts. This places the full
12V across the fan for the ton period of the pulse. When
the duty cycle of the drive pulse is 100% (full on,
ton = t), the fan will run at full speed. As the duty cycle
is decreased (pulse on time “ton” is lowered), the fan
will slow down proportionally. With the TC646B,
TC648B and TC649B devices, the duty cycle is con-
trolled by the VIN input and can also be terminated by
the VAS input (auto-shutdown). This is described in
more detail in Section 5.5, “Output Drive Device
Selection”.
4.3
Fan Start-up
Often overlooked in fan speed control is the actual
start-up control period. When starting a fan from a non-
operating condition (fan speed is zero revolutions per
minute (RPM)), the desired PWM duty cycle or average
fan voltage cannot be applied immediately. Since the
fan is at a rest position, the fan’s inertia must be over-
come to get it started. The best way to accomplish this
is to apply the full rated voltage to the fan for a minimum
of one second. This will ensure that in all operating
environments, the fan will start and operate properly.
An example of the start-up timing is shown in
A key feature of the TC646B/TC648B/TC649B devices
is the start-up timer. When power is first applied to the
device, or when the device is brought out of the shut-
down/auto-shutdown modes of operation, the VOUT
output will go to a high state for 32 PWM cycles (one
second for CF = 1 F). This will drive the fan to full
speed for this time frame.
During the start-up period for the TC646B and TC649B
devices, the SENSE pin is being monitored for fan
pulses. If pulses are detected during this period, the fan
speed controller will then move to PWM operation. If
pulses are not detected during the start-up period, the
start-up timer is activated again. If pulses are not
detected at the SENSE pin during this additional
period, the FAULT output will go low to indicate that a
fan fault condition has occurred. See Section 4.7,
“FAULT/OTF Output”, for more details.
4.4
PWM Frequency & Duty Cycle
Control (CF & VIN Pins)
The frequency of the PWM pulse train is controlled by
the CF pin. By attaching a capacitor to the CF pin, the
frequency of the PWM pulse train can be set to the
desired value. The typical PWM frequency for a 1.0 F
capacitor is 30 Hz. The frequency can be adjusted by
raising or lowering the value of the capacitor. The CF
pin functions as a ramp generator. The voltage at this
pin will ramp from 1.20V to 2.60V (typically) as a saw-
tooth waveform. An example of this is shown in
FIGURE 4-3:
CF Pin Voltage.
The duty cycle of the PWM output is controlled by the
voltage at the VIN input pin. The duty cycle of the PWM
output is produced by comparing the voltage at the VIN
pin to the voltage ramp at the CF pin. When the voltage
at the VIN pin is 1.20V, the duty cycle will be 0%. When
the voltage at the VIN pin is 2.60V, the PWM duty cycle
will be 100% (these are both typical values). The
VIN-to-PWM duty cycle relationship is shown in
The lower value of 1.20V is referred to as “VCMIN” and
the 2.60V threshold is referred to as “VCMAX”. A calcu-
lation for duty cycle is shown in the equation below. The
voltage range between VCMIN and VCMAX is character-
ized as “VCSPAN“ and has a typical value of 1.4V, with
minimum and maximum values of 1.3V and 1.5V,
respectively.
EQUATION
PWM DUTY CYCLE
FAN
12V
QDRIVE
TC646B
TC648B
TC649B
VDD
GND
VOUT
G
D
S
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
0
20
406080
100
Time (msec)
C
FVoltage
(V)
CF = 1 F
VCMAX
VCMIN
Duty Cycle (%) =
VCMAX - VCMIN
(VIN - VCMIN) * 100
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC649E | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:PWM Fan Speed Controller with Auto-Shutdown and FanSense⑩ Technology |
| TC649EOA | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & 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 |
| TC649EOATR | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & 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 |
| TC649EPA | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:PWM Fan Speed Controller with Auto-Shutdown and FanSense⑩ Technology |
| TC649EUA | 功能描述:马达/运动/点火控制器和驱动器 Shtdn & 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 |
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