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參數(shù)資料
| 型號： | MAX6649MUA/V+ |
| 廠商： | Maxim Integrated |
| 文件頁數(shù)： | 13/16頁 |
| 文件大小： | 194K |
| 描述： | IC SENSOR REMOTE SMBUS 8UMAX |
| 產(chǎn)品培訓模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標準包裝： | 50 |
| 功能： | 溫度監(jiān)控系統(tǒng)（傳感器） |
| 傳感器類型： | 內(nèi)部和外部 |
| 感應(yīng)溫度： | -55°C ~ 125°C，外部傳感器 |
| 精確度： | ±3°C 本地（最大），±3.2°C 遠程（最大） |
| 拓撲： | ADC，多路復(fù)用器，寄存器庫 |
| 輸出類型： | I²C?/SMBus? |
| 輸出警報： | 是 |
| 輸出風扇： | 是 |
| 電源電壓： | 3 V ~ 5.5 V |
| 工作溫度： | -55°C ~ 125°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-TSSOP，8-MSOP（0.118"，3.00mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 8-uMAX |
| 包裝： | 管件 |
ADC Noise Filtering
The integrating ADC used has good noise rejection for
low-frequency signals such as 60Hz/120Hz power-sup-
ply hum. In noisy environments, high-frequency noise
reduction is needed for high-accuracy remote mea-
surements. The noise can be reduced with careful PC
board layout and proper external noise filtering.
High-frequency EMI is best filtered at DXP and DXN with
an external 2200pF capacitor. Larger capacitor values
can be used for added filtering, but do not exceed
3300pF because larger values can introduce errors due
to the rise time of the switched current source.
PC Board Layout
Follow these guidelines to reduce the measurement
error of the temperature sensors:
1) Place the MAX6646/MAX6647/MAX6649 as close as
is practical to the remote diode. In noisy environ-
ments, such as a computer motherboard, this dis-
tance can be 4in to 8in (typ). This length can be
increased if the worst noise sources are avoided.
Noise sources include CRTs, clock generators,
memory buses, and ISA/PCI buses.
2) Do not route the DXP-DXN lines next to the deflec-
tion coils of a CRT. Also, do not route the traces
across fast digital signals, which can easily intro-
duce 30癈 error, even with good filtering.
3) Route the DXP and DXN traces in parallel and in
close proximity to each other, away from any higher
voltage traces, such as 12VDC. Leakage currents
from PC board contamination must be dealt with
carefully since a 20M?leakage path from DXP to
ground causes about 1癈 error. If high-voltage traces
are unavoidable, connect guard traces to GND on
either side of the DXP-DXN traces (Figure 4).
4) Route through as few vias and crossunders as possi-
ble to minimize copper/solder thermocouple effects.
5) When introducing a thermocouple, make sure that
both the DXP and the DXN paths have matching
thermocouples. A copper-solder thermocouple
exhibits 3糣/癈, and takes about 200糣 of voltage
error at DXP-DXN to cause a 1癈 measurement
error. Adding a few thermocouples causes a negligi-
ble error.
6) Use wide traces. Narrow traces are more inductive
and tend to pick up radiated noise. The 10mil widths
and spacing recommended in Figure 4 are not
absolutely necessary, as they offer only a minor
improvement in leakage and noise over narrow
traces. Use wider traces when practical.
7) Add a 200?resistor in series with V
CC
for best noise
filtering (see Typical Operating Circuit).
8) Copper cannot be used as an EMI shield; only fer-
rous materials such as steel work well. Placing a
copper ground plane between the DXP-DXN traces
and traces carrying high-frequency noise signals
does not help reduce EMI.
Twisted-Pair and Shielded Cables
Use a twisted-pair cable to connect the remote sensor
for remote-sensor distance longer than 8in, or in very
noisy environments. Twisted-pair cable lengths can be
between 6ft and 12ft before noise introduces excessive
errors. For longer distances, the best solution is a
shielded twisted pair like that used for audio micro-
phones. For example, Belden 8451 works well for dis-
tances up to 100ft in a noisy environment. At the
device, connect the twisted pair to DXP and DXN and
the shield to GND. Leave the shield unconnected at the
remote sensor.
For very long cable runs, the cables parasitic capaci-
tance often provides noise filtering, so the 2200pF
capacitor can often be removed or reduced in value.
Cable resistance also affects remote-sensor accuracy.
For every 1?of series resistance, the error is approxi-
mately 0.5癈.
Thermal Mass and Self-Heating
When sensing local temperature, these devices are
intended to measure the temperature of the PC board
to which the devices are soldered. The leads provide a
good thermal path between the PC board traces and
the die. Thermal conductivity between the die and the
ambient air is poor by comparison, making air tempera-
ture measurements impractical. Because the thermal
mass of the PC board is far greater than that of the
MAX6646/MAX6647/MAX6649, the device follows tem-
perature changes on the PC board with little or no per-
ceivable delay.
+145癈 Precision SMBus-Compatible Remote/
Local Sensors with Overtemperature Alarms
13
MINIMUM
10 MILS
10 MILS
10 MILS
10 MILS
GND
DXN
DXP
GND
Figure 4. Recommended DXP-DXN PC Traces
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參數(shù)描述 |
|---|---|
| MAX6649YMUA+ | 功能描述:板上安裝溫度傳感器 145C SMBus-Comp Remote/Local Sensor 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(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: 安裝風格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6649YMUA+T | 功能描述:板上安裝溫度傳感器 145C SMBus-Comp Remote/Local Sensor 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(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: 安裝風格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX664C/D | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| MAX664CJA | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| MAX664CPA | 功能描述:低壓差穩(wěn)壓器 - LDO RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調(diào)節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
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