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參數資料
| 型號： | TC647VOART |
| 元件分類： | 運動控制電子 |
| 英文描述： | BRUSHLESS DC MOTOR CONTROLLER, PDSO8 |
| 封裝： | SOIC-8 |
| 文件頁數： | 15/15頁 |
| 文件大?。?/td> | 117K |
| 代理商： | TC647VOART |
9
TC647-2
12/05/00
TC647
PWM Fan Speed Controller with FanSense*
2001 Microchip Technology Inc.
DS21447A
VMIN = VDD x
R2
R1 + R2
Equation 5.
Solving for the relationship between R1 and R2 results
in the following equation:
R1 = R2 x VDD – VMIN
VMIN
Equation 6.
In the case of this example, R1 = (1.762) R2. Substitut-
ing this relationship back into Equation 4 yields the resistor
values:
R2 =18.1k
, and
R1 = 31.9k
In this case, the standard values of 32k
and 18k are
very close to the calculated values and would be more than
adequate.
One boundary condition which may impact the selection
of the minimum fan speed is the irregular activation of the
Diagnostic Timer due to the TC647 “missing” fan commuta-
tion pulses at low speeds. Typically, this only occurs at very
low duty-cycles (25% or less). It is a natural consequence
of low PWM duty-cycles. Recall that the SENSE function
detects commutation of the fan as disturbances in the
current through RSENSE. These can only occur when the fan
is energized, i.e., VOUT is “on”. At very low duty-cycles, the
VOUT output is “off” most of the time. The fan may be rotating
normally, but the commutation events are occuring during
the PWM’s off-time.
The phase relationship between the fan’s commutation
and the PWM edges tends to “walk around” as the system
operates. At certain points, the TC647 may fail to capture a
pulse within the 32-cycle Missing Pulse Detector window.
When this happens, the 3-cycle Diagnostic Timer will be
activated, the VOUT output will be active continuously for
three cycles and, if the fan is operating normally, a pulse will
be detected. If all is well, the system will return to normal
operation. There is no harm in this behavior, but it may be
audible to the user as the fan will accelerate briefly when the
Diagnostic Timer fires. For this reason, it is recommended
that VMIN be set no lower than 1.8V.
(FanSenseTM) Network (RSENSE and CSENSE)
The network comprised of RSENSE and CSENSE allow the
TC647 to detect commutation of the fan motor(FanSenseTM).
This network can be thought of as a differentiator and
threshold detector. The function of RSENSE is to convert the
fan current into a voltage. CSENSE serves to AC-couple this
voltage signal and provide a ground-referenced input to the
SENSE pin. Designing a proper SENSE Network is simply
a matter of scaling RSENSE to provide the necessary amount
of gain, i.e., the current-to-voltage conversion ratio. A 0.1
F
ceramic capacitor is recommended for CSENSE. Smaller
values require larger sense resistors, and higher value
capacitors are bulkier and more expensive. Using a 0.1
F
results in reasonable values for RSENSE. Figure 7 illustrates
a typical SENSE Network. Figure 8 shows the waveforms
observed using a typical SENSE Network.
Table 1 lists the recommended values of RSENSE ac-
cording to the nominal operating current of the fan. Note that
the current draw specified by the fan manufacturer may not
be the fan’s nominal operating current, but may be a worst-
case rating for near-stall conditions. The values in the table
refer to actual average operating current. If the fan current
falls between two of the values listed, use the higher resistor
value. The end result of employing Table 1 is that the signal
developed across the sense resistor is approximately
450mV in amplitude.
Table 1. RSENSE vs. Fan Current
Nominal Fan Current (mA)
RSENSE (
)
50
9.1
100
4.7
150
3.0
200
2.4
250
2.0
300
1.8
350
1.5
400
1.3
450
1.2
500
1.0
Figure 8. SENSE Waveforms
1
Ch1
100mV
Tek Run: 10.0kS/s Sample
Ch2
100mV
M5.00ms
Ch1
142mV
GND
[
T
]
T
Waveform @ Sense Resistor
90mV
50mV
GND
Waveform @ Sense Pin
2
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相關代理商/技術參數 |
參數描述 |
|---|---|
| TC647VOATR | 功能描述:馬達/運動/點火控制器和驅動器 w/Fault Dtct RoHS:否 制造商:STMicroelectronics 產品: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 安裝風格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC647VPA | 功能描述:馬達/運動/點火控制器和驅動器 w/Fault Dtct RoHS:否 制造商:STMicroelectronics 產品: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 安裝風格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC647VUA | 功能描述:馬達/運動/點火控制器和驅動器 w/Fault Dtct RoHS:否 制造商:STMicroelectronics 產品: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 安裝風格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC647VUATR | 功能描述:馬達/運動/點火控制器和驅動器 w/Fault Dtct RoHS:否 制造商:STMicroelectronics 產品: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 安裝風格:SMD/SMT 封裝 / 箱體:HTSSOP-28 封裝:Tube |
| TC648 | 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 |
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