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| 型號(hào)： | ADM1025AARQ |
| 廠商： | ON Semiconductor |
| 文件頁(yè)數(shù)： | 4/19頁(yè) |
| 文件大小： | 0K |
| 描述： | IC MONITOR SYS/VOLT 5CH 16QSOP |
| 產(chǎn)品變化通告： | MFG CHG Notification ADI to ON Semi |
| 標(biāo)準(zhǔn)包裝： | 98 |
| 應(yīng)用： | PC，PDA |
| 接口： | I²C |
| 電源電壓： | 3 V ~ 5.5 V |
| 封裝/外殼： | 16-SSOP（0.154"，3.90mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 16-QSOP |
| 包裝： | 管件 |
| 安裝類型： | 表面貼裝 |
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ADM1025, ADM1025A
http://onsemi.com
12
Layout Considerations
Digital boards can be electrically noisy environments and
care must be taken to protect the analog inputs from noise,
particularly when measuring the very small voltages from a
remote diode sensor. The following precautions should be
taken:
1. Place the ADM1025/ADM1025A as close as
possible to the remote sensing diode. Provided that
the worst noise sources, such as clock generators,
data/address buses, and CRTs, are avoided, this
distance can be four to eight inches.
2. Route the D+ and D tracks close together, in
parallel, with grounded guard tracks on each side.
Provide a ground plane under the tracks if
possible.
3. Use wide tracks to minimize inductance and
reduce noise pickup. 10 mil track minimum width
and spacing is recommended.
Figure 15. Arrangement of Signal Tracks
10 MIL
GND
D
D+
GND
4. Try to minimize the number of copper/solder
joints, which can cause thermocouple effects.
Where copper/solder joints are used, make sure
that they are in both the D+ and D path and at the
same temperature.
Thermocouple effects should not be a major
problem as 1C corresponds to about 240
mV, and
thermocouple voltages are about 3
mV/C of
temperature difference. Unless there are two
thermocouples with a big temperature differential
between them, thermocouple voltages should be
much less than 200
mV.
5. Place 0.1
mF bypass and 1 nF input filter
capacitors close to the ADM1025/ADM1025A.
6. If the distance to the remote sensor is more than
eight inches, the use of twisted pair cable is
recommended. This will work up to about 6 to
12 feet.
7. For really long distances (up to 100 feet) use
shielded twisted pair, such as Belden #8451
microphone cable. Connect the twisted pair to D+
and D and the shield to GND close to the
ADM1025/ADM1025A. Leave the remote end of
the shield unconnected to avoid ground loops.
Because the measurement technique uses switched
current sources, excessive cable and/or filter capacitance
can affect the measurement. When using long cables, the
filter capacitor may be reduced or removed.
Cable resistance can also introduce errors. 1
W series
resistance introduces about 0.5C error.
Limit Values
High and low limit values for each measurement channel
are stored in the appropriate limit registers. As each channel
is measured, the measured value is stored and compared
with the programmed limit.
Status Registers
The results of limit comparisons are stored in Status
Registers 1 and 2. The Status Register bit for a particular
measurement channel reflects the status of the last
measurement and limit comparison on that channel. If a
measurement is within limits, the corresponding Status
Register bit will be cleared to “0.” If the measurement is out
of limits, the corresponding status register bit will be set to
“1.”
The state of the various measurement channels may be
polled by reading the Status Registers over the serial bus.
Reading the Status Registers does not affect their contents.
Out-of-limit temperature/voltage events may also be used to
generate an interrupt so that remedial action, such as turning
on a cooling fan, may be taken immediately. This is
described in the section on RST and INT.
Monitoring Cycle Time
The monitoring cycle begins when a 1 is written to the
Start Bit (Bit 0) of the Configuration Register. The ADC
measures each analog input in turn and as each measurement
is completed the result is automatically stored in the
appropriate value register. This “round-robin” monitoring
cycle continues until it is disabled by writing a 0 to Bit 0 of
the Configuration Register.
As the ADC will normally be left to free-run in this
manner, the time taken to monitor all the analog inputs will
normally not be of interest, since the most recently measured
value of any input can be read out at any time.
Input Safety
Scaling of the analog inputs is performed on-chip, so
external attenuators are normally not required. However,
since the power supply voltages will appear directly at the
pins, it is advisable to add small external resistors in series
with the supply traces to the chip to prevent damaging the
traces or power supplies should an accidental short such as
a probe connect two power supplies together.
As the resistors will form part of the input attenuators,
they will affect the accuracy of the analog measurement if
their value is too high. The analog input channels are
calibrated assuming an external series resistor of 500
W, and
the accuracy will remain within specification for any value
from zero to 1 k
W, so a standard 510 W resistor is suitable.
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| ADM1025AARQ-REEL | 制造商:Rochester Electronics LLC 功能描述:PC HARDWARE MONITOR I.C. - Tape and Reel |
| ADM1025AARQZ | 功能描述:IC MONITOR SYS/VOLT 5CH 16QSOP RoHS:是 類別:集成電路 (IC) >> 接口 - 專用 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 應(yīng)用:PDA，便攜式音頻/視頻，智能電話 接口:I²C，2 線串口 電源電壓:1.65 V ~ 3.6 V 封裝/外殼:24-WQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-QFN 裸露焊盤（4x4） 包裝:帶卷 (TR) 安裝類型:表面貼裝 產(chǎn)品目錄頁(yè)面:1015 (CN2011-ZH PDF) 其它名稱:296-25223-2 |
| ADM1025ARQ | 功能描述:IC MONITOR SYS/VOLT 5CH 16QSOP RoHS:否 類別:集成電路 (IC) >> 接口 - 專用 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 應(yīng)用:PDA，便攜式音頻/視頻，智能電話 接口:I²C，2 線串口 電源電壓:1.65 V ~ 3.6 V 封裝/外殼:24-WQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-QFN 裸露焊盤（4x4） 包裝:帶卷 (TR) 安裝類型:表面貼裝 產(chǎn)品目錄頁(yè)面:1015 (CN2011-ZH PDF) 其它名稱:296-25223-2 |
| ADM1025ARQ-REEL | 功能描述:IC MONITOR SYS/VOLT 5CH 16QSOP RoHS:否 類別:集成電路 (IC) >> 接口 - 專用 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 應(yīng)用:PDA，便攜式音頻/視頻，智能電話 接口:I²C，2 線串口 電源電壓:1.65 V ~ 3.6 V 封裝/外殼:24-WQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-QFN 裸露焊盤（4x4） 包裝:帶卷 (TR) 安裝類型:表面貼裝 產(chǎn)品目錄頁(yè)面:1015 (CN2011-ZH PDF) 其它名稱:296-25223-2 |
| ADM1025ARQ-REEL7 | 功能描述:IC MONITOR SYS/VOLT 5CH 16QSOP RoHS:否 類別:集成電路 (IC) >> 接口 - 專用 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 應(yīng)用:PDA，便攜式音頻/視頻，智能電話 接口:I²C，2 線串口 電源電壓:1.65 V ~ 3.6 V 封裝/外殼:24-WQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:24-QFN 裸露焊盤（4x4） 包裝:帶卷 (TR) 安裝類型:表面貼裝 產(chǎn)品目錄頁(yè)面:1015 (CN2011-ZH PDF) 其它名稱:296-25223-2 |
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