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參數資料
| 型號： | MAX6678AEP92+ |
| 廠商： | Maxim Integrated |
| 文件頁數： | 8/19頁 |
| 文件大小： | 669K |
| 描述： | IC TEMP MONITOR 2CH PWM 20-QSOP |
| 產品培訓模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標準包裝： | 50 |
| 功能： | 溫度監控器 |
| 傳感器類型： | 內部和外部 |
| 精確度： | ±4°C（最小值） |
| 輸出類型： | SMBus? |
| 輸出警報： | 是 |
| 輸出風扇： | 是 |
| 電源電壓： | 3 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 20-SSOP（0.154"，3.90mm 寬） |
| 供應商設備封裝： | 20-QSOP |
| 包裝： | 管件 |
PWM Output
1) The PWMOUT_ signals are normally used in one of
three ways to control the fans speed: PWMOUT_ dri-
ves the gate of a MOSFET or the base of a bipolar
transistor in series with the fans power supply. The
Typical Application Circuit shows the PWMOUT_ dri-
ving an n-channel MOSFET. In this case, the PWM
invert bit (D4 in register 02h) is set to 1. Figure 4
shows PWMOUT_ driving a p-channel MOSFET and
the PWM invert bit must be set to zero.
2) PWMOUT_ is converted (using an external circuit)
into a DC voltage that is proportional to duty cycle.
This duty-cycle-controlled voltage becomes the
power supply for the fan. This approach is less effi-
cient than 1), but can result in quieter fan operation.
Figure 5 shows an example of a circuit that converts
the PWM signal to a DC voltage. Because this circuit
produces a full-scale output voltage when PWMOUT
= 0V, bit D4 in register 02h should be set to zero.
3) PWMOUT_ directly drives the logic-level PWM
speed-control input on a fan that has this type of
input. This approach requires fewer external compo-
nents and combines the efficiency of 1) with the low
noise of 2). An example of PWMOUT_ driving a fan
with a speed-control input is shown in Figure 6. Bit
D4 in register 02h should be set to 1 when this con-
figuration is used.
Whenever the fan has to start turning from a motionless
state, PWMOUT_ is forced high for 2s. After this spin-up
period, the PWMOUT_ duty cycle settles to the prede-
termined value. Whenever spin-up is disabled (bit 2 in
the configuration byte = 1) and the fan is off, the duty
cycle changes immediately from zero to the nominal
value, ignoring the duty-cycle rate-of-change setting.
The frequency-select register controls the frequency of
the PWM signal. When the PWM signal modulates the
power supply of the fan, a low PWM frequency (usually
33Hz) should be used to ensure the circuitry of the
brushless DC motor has enough time to operate. When
driving a fan with a PWM-to-DC circuit as in Figure 5,
the highest available frequency (35kHz) should be
used to minimize the size of the filter capacitors. When
using a fan with a PWM control input, the frequency
normally should be high as well, although some fans
have PWM inputs that accept low-frequency drive.
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
8 _______________________________________________________________________________________
V
CC
PWMOUT
10k&
5V
P
Figure 4. Driving a P-Channel MOSFET for Top-Side PWM Fan
Drive
+3.3V
PWMOUT
18k&
27k&
10k&
120k&
+3.3V
+12V
500k&
V
OUT
TO FAN
1礔
1礔
0.01礔
0.1礔
Figure 5. Driving a Fan with a PWM-to-DC Circuit
V
CC
PWMOUT
4.7k&
5V
Figure 6. Controlling a PWM Input Fan with the MAX6678s
PWM Output (Typically, the 35kHz PWM Frequency Is Used)
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX6678AEP92+ | 功能描述:板上安裝溫度傳感器 2Ch Temperature Monitor RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| MAX6678AEP92+T | 功能描述:板上安裝溫度傳感器 2Ch Temperature Monitor RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| MAX6678AEP92-T | 功能描述:板上安裝溫度傳感器 2Ch Temperature Monitor RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| MAX6678AEP94 | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| MAX6678AEP94+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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