參數(shù)資料
型號(hào)： TC664EUN
廠商： Microchip Technology Inc.
英文描述： SMBus⑩ PWM Fan Speed Controllers With Fan Fault Detection
中文描述： ⑩的SMBus PWM風(fēng)扇與風(fēng)扇轉(zhuǎn)速控制器故障檢測(cè)
文件頁(yè)數(shù)： 22/36頁(yè)
文件大?。?/td> 695K
代理商： TC664EUN
TC664/TC665
DS21737A-page 22
2002 Microchip Technology Inc.
7.0
APPLICATIONS INFORMATION
7.1
Connecting to the SMBus
The SMBus is an open collector bus, requiring pull-up
resistors connected to the SDA and SCLK lines. This
configuration is shown in Figure 7-1.
FIGURE 7-1:
SMBus.
Pull-up Resistors On
The number of devices connected to the bus is limited
only by the maximum rise and fall times of the SDA and
SCLK lines. Unlike I
2
C specifications, SMBus does not
specify a maximum bus capacitance value. Rather, the
SMBus specification calls out that the maximum current
through the pull-up resistor be 350 μA (minimum,
100 μA, is also specified). Therefore, the value of the
pull-up resistors will vary depending on the system’s
bias voltage, V
DD
. Minimizing bus capacitance is still
very important as it directly effects the rise and fall times
of the SDA and SCLK lines. The range for pull-up resis-
tor values for a 5 V system are shown in Figure 7-1.
Although SMBus specifications only require the SDA
and SCLK lines to pull down 350 μA, with a maximum
voltage drop of 0.4 V, the TC664/TC665 devices have
been designed to meet a maximum voltage drop of
0.4 V with 3 mA of current. This allows lower values of
pull-up resistors to be used, which will allow higher bus
capacitance. If this is to be done, all devices on the bus
must be able to meet the same pull down current
requirements as well.
A possible configuration using multiple devices on the
SMBus is shown in Figure 7-2.
FIGURE 7-2:
Multiple Devices on SMBus.
7.2
Setting the PWM Frequency
The PWM frequency of the V
OUT
output is set by the
capacitor value attached to the C
F
pin. The PWM fre-
quency will be 30 Hz (typical) for a 1 μF capacitor. The
relationship between frequency and capacitor value is
linear, making alternate frequency selections easy.
As stated in previous sections, the PWM frequency
should be kept in the range of 15 Hz to 35 Hz. This will
eliminate the possibility of having audible frequencies
when varying the duty cycle of the fan drive.
A very important factor to consider when selecting the
PWM frequency for the TC664/TC665 devices is the
RPM rating of the selected fan and the minimum duty
cycle that you will be operating at. For fans that have a
full speed rating of 3000 RPM or less, it is desirable to
use a lower PWM frequency. A lower PWM frequency
allows for a longer time period to monitor the fan cur-
rent pulses. The goal is to be able to monitor at least
two fan current pulses during the on time of the V
OUT
output.
Example:
Your system design requirement is to oper-
ate the fan at 50% duty cycle when ambient tempera-
tures are below 20°C. The fan full speed RPM rating is
3000 RPM and has four current pulses per rotation. At
50% duty cycle, the fan will be operating at approxi-
mately 1500 RPM.
EQUATION
If one fan revolution occurs in 40 msec, then each fan
pulse occurs 10 msec apart. In order to detect two fan
current pulses, the on time of the V
OUT
pulse must be
at least 20 msec. With the duty cycle at 50%, the total
period of one cycle must be at least 40 msec, which
makes the PWM frequency 25 Hz. For this example, a
PWM frequency of 20 Hz is recommended. This would
define a C
F
capacitor value of 1.5 μF.
P
SDA
SCLK
V
DD
R
R
M
TC664/TC665
Range for R: 13.2 k
to 46 k
for V
DD
= 5.0 V
SDA SCLK
PIC16F876
Microcontroller
TCN75
Temperature
Sensor
24LC01
EEPROM
TC664/TC665
Fan Speed
Controller
Time for one revolution (msec.)
60
1000
×
1500
40
=
=
相關(guān)PDF資料
PDF描述
TC664 SMBus⑩ PWM Fan Speed Controllers With Fan Fault Detection
TC665 SMBus⑩ PWM Fan Speed Controllers With Fan Fault Detection
TC670ECH Tiny Predictive Fan Failure Detector
TC7400BP TC7400BP
TC74AC00F Quad 2-Input NAND Gate(四2輸入與非門(mén))
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TC664EUNTR 功能描述:馬達(dá)/運(yùn)動(dòng)/點(diǎn)火控制器和驅(qū)動(dòng)器 Single RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類(lèi)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
TC665 制造商:MICROCHIP 制造商全稱(chēng):Microchip Technology 功能描述:SMBus⑩ PWM Fan Speed Controllers With Fan Fault Detection
TC665EUN 功能描述:馬達(dá)/運(yùn)動(dòng)/點(diǎn)火控制器和驅(qū)動(dòng)器 Single RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類(lèi)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
TC665EUNTR 功能描述:馬達(dá)/運(yùn)動(dòng)/點(diǎn)火控制器和驅(qū)動(dòng)器 Single RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Stepper Motor Controllers / Drivers 類(lèi)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
TC67 功能描述:鋁質(zhì)電解電容器 - 帶引線(xiàn) 40uF 350V RoHS:否 制造商:Kemet 引線(xiàn)類(lèi)型: 電容:220 uF 容差:20 % 電壓額定值:25 V 工作溫度范圍: 端接類(lèi)型:Radial 外殼直徑:8 mm 外殼長(zhǎng)度:11 mm 引線(xiàn)間隔:5 mm 產(chǎn)品:General Purpose Electrolytic Capacitors 封裝:Bulk
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*