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參數(shù)資料
| 型號(hào)： | MAX6661AEE+T |
| 廠商： | Maxim Integrated |
| 文件頁(yè)數(shù)： | 16/19頁(yè) |
| 文件大?。?/td> | 257K |
| 描述： | IC REG FAN SPEED 16-QSOP |
| 標(biāo)準(zhǔn)包裝： | 2,500 |
| 功能： | 風(fēng)扇控制，溫度監(jiān)控器 |
| 傳感器類(lèi)型： | 外部 |
| 感應(yīng)溫度： | 外部傳感器 |
| 精確度： | ±5°C（最小值） |
| 拓?fù)洌?/td> | ADC，比較器，風(fēng)扇控制，多路復(fù)用器，寄存器庫(kù) |
| 輸出類(lèi)型： | SPI? |
| 輸出警報(bào)： | 是 |
| 輸出風(fēng)扇： | 是 |
| 電源電壓： | 3 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 125°C |
| 安裝類(lèi)型： | 表面貼裝 |
| 封裝/外殼： | 16-SSOP（0.154"，3.90mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 16-QSOP |
| 包裝： | 帶卷 (TR) |
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using the FSC register. By selecting fan open-loop
mode, the MAX6661 automatically invokes thermal
open-loop mode.
Fan Conversion Rate Register
The FCR register (Table 6) programs the fans update
time interval in free-running autonomous mode
(RUN/STOP = 0). The conversion rate bytes POR state
is 02h (0.25Hz). The MAX6661 uses only the 3LSBs of
this register. The 5MSBs are dont cares. The update
rate tolerance is ?5% (max) at any rate setting.
Fan Driver
The fan driver consists of an amplifier and low-side
NMOS power device whose drain is connected to FAN
and is the connection for the low side of the fan. There
is an internal connection from the fan to the input of the
amplifier. The FET has 4& on-resistance with 320mA
(typ) current limit. The driver has a thermal shutdown
sensor that senses the drivers temperature. It shuts
down the driver if the temperature exceeds +150癈.
The driver is reactivated once the temperature has
dropped below +140癈.
TACH IN
The TACH IN input connects directly to the tachometer
output of a fan. Most commercially available fans have
two tachometer pulses per revolution. The tachometer
input is fully compatible with tachometer signals, which
are pulled up to V
FAN
.
Commutating Current Pulses
When a fan does not come equipped with a tachometer
output, the MAX6661 uses commutating generated cur-
rent pulses for speed detection. This mode is entered
by setting the FG registers bit 1 to 1. An internal pulse
is generated whenever a step increase occurs in the
fan current. Connecting an external resistor between
the GAIN pin and V
CC
can reduce the sensitivity of
pulses to changes in fan current. In general, the lower
the resistor value, the lower the sensitivity, and the fan
is easier to turn ON and can use a smaller external
capacitor across its terminals. A suitable resistor range
is 1k& to 5k&.
Fan-Failure Detection
The MAX6661 detects fan failure by comparing the
value in the fan tachometer period (FTP) register, a
READ ONLY register, with a limit stored in the fan
tachometer period limit (FTPL) register (Table 11). A
counter counts the number of on-chip oscillator pulses
between successive tachometer pulses and loads its
value into the FTP register every time a tachometer
pulse arrives. If the value in FTP is greater than the
value in FTPL, a failure is indicated. In fan closed loop,
a flag is activated when the fan is at full speed.
Set the fan tachometer period limit byte to:
f
TACH
= 8415 / [N f]
where N = fan-fail ratio and f
TACH
= maximum frequen-
cy of the fan tachometer. The factor N is less than 1
and produces a fan-failure indication when the fan
should be running at full speed, but is only reaching a
factor of N of its expected frequency. The factor N is
typically set to 0.75 for all fan speeds except at very
low speeds where a fan failure is indicated by an over-
flow of the fan-speed counter. The overflow flag cannot
be viewed separately in the status byte but is ORed
with bit 0, the fan-fail bit.
Applications Information
Mode Register
Resistance in series with the remote-sensing junction
causes conversion errors on the order of 0.5癈 per
ohm.
The MAX6661 mode register gives the ability to elimi-
nate the effects of external series resistance of up to
several hundred ohms on the remote temperature mea-
surement and to adjust the temperature-measuring
ADC to suit different types of remote-diode sensor. For
systems using external switches or long cables to con-
nect to the remote sensor, a parasitic resistance can-
cellation mode can be entered by setting mode register
bit 7 = 1. This mode requires a longer conversion time
and so can only be used for fan conversion rates of
1Hz or slower. Bits 6, 1, and 0 of the mode register are
not used. Use bits 52 to adjust the ADC gain to
achieve accurate temperature measurements with
diodes not included in the recommended list or to indi-
vidually calibrate the MAX6661 for use in specific con-
trol systems. These bits adjust gain to set the
temperature reading at +25癈, using twos complement
format reading. Bit 5 is the sign (1 = increase, 0 =
decrease), bit 4 = 2癈 shift, bit 3 = 1癈 shift, bit 2 =
1/2癈 shift. Origin of gain curve is referred to 0癒. To
use this feature, the sensor must be calibrated by the
user.
General Programming Techniques
The full-scale range of the fan-regulation loop is
designed to accommodate fans operating between the
1000rpm to 8000rpm range of different fans. An on-
chip 8415Hz oscillator is used to generate the 33Hz to
66Hz reference frequency. Choose the FTD value such
that the fan full-speed frequency divided by this value
falls in the 33Hz to 66Hz range. The full-scale reference
frequency is further divided by the value in the FSC
Remote Temperature-Controlled Fan-Speed
Regulator with SPI-Compatible Interface
16 ______________________________________________________________________________________
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| MAX6662EVKIT+ | 功能描述:板上安裝溫度傳感器 MAX6662 Eval Kit RoHS:否 制造商:Omron Electronics 輸出類(lèi)型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)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(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6662MSA | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類(lèi)型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)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(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6662MSA+ | 功能描述:板上安裝溫度傳感器 12-Bit + Sign Temperature Sensor RoHS:否 制造商:Omron Electronics 輸出類(lèi)型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)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(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6662MSA+T | 功能描述:板上安裝溫度傳感器 12-Bit + Sign Temperature Sensor RoHS:否 制造商:Omron Electronics 輸出類(lèi)型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)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(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
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