Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

ADM1022 Datasheet(PDF) 10 Page - Analog Devices

Part # ADM1022
Description  Low-Cost PC Temperature Monitor and Fan Control ASIC
Download  19 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  AD [Analog Devices]
Direct Link  http://www.analog.com
Logo AD - Analog Devices

ADM1022 Datasheet(HTML) 10 Page - Analog Devices

Back Button ADM1022 Datasheet HTML 6Page - Analog Devices ADM1022 Datasheet HTML 7Page - Analog Devices ADM1022 Datasheet HTML 8Page - Analog Devices ADM1022 Datasheet HTML 9Page - Analog Devices ADM1022 Datasheet HTML 10Page - Analog Devices ADM1022 Datasheet HTML 11Page - Analog Devices ADM1022 Datasheet HTML 12Page - Analog Devices ADM1022 Datasheet HTML 13Page - Analog Devices ADM1022 Datasheet HTML 14Page - Analog Devices Next Button
Zoom Inzoom in Zoom Outzoom out
 10 / 19 page
background image
REV. 0
ADM1022
–10–
LOW-PASS
FILTER
fC = 65kHz
BIAS
DIODE
REMOTE
SENSING
TRANSISTOR
I
N
IIBIAS
D+
D–
VOUT+
VOUT–
TO
ADC
VDD
Figure 12. Signal Conditioning
If a discrete transistor is used, the collector will not be grounded,
and should be linked to the base. If a PNP transistor is used the
base is connected to the D– input and the emitter to the D+ input.
If an NPN transistor is used, the emitter is connected to the D–
input and the base to the D+ input.
Table II. Temperature Data Format
Temperature
Digital Output
–128
°C
1000 0000
–125
°C
1000 0011
–100
°C
1001 1100
–75
°C
1011 0101
–50
°C
1100 1110
–25
°C
1110 0111
–1
°C
1111 1111
0
°C
0000 0000
+1
°C
0000 0001
+10
°C
0000 1010
+25
°C
0001 1001
+50
°C
0011 0010
+75
°C
0100 1011
+100
°C
0110 0100
+125
°C
0111 1101
+127
°C
0111 1111
To prevent ground noise interfering with the measurement, the
more negative terminal of the sensor is not referenced to ground,
but is biased above ground by an internal diode at the D– input.
If the sensor is used in a very noisy environment, a capacitor of
value up to 1000 pF may be placed between the D+ and D–
inputs to filter the noise.
To measure
∆VBE, the sensor is switched between operating
currents of I and N
× I. The resulting waveform is passed through
a 65 kHz low-pass filter to remove noise, thence to a chopper-
stabilized amplifier that performs the functions of amplification
and rectification of the waveform to produce a dc voltage pro-
portional to
∆V
BE. This voltage is measured by the ADC to give
a temperature output in 8-bit twos complement format. To fur-
ther reduce the effects of noise, digital filtering is performed by
averaging the results of 16 measurement cycles. An external
temperature measurement takes nominally 9.6 ms.
LAYOUT CONSIDERATIONS
Digital boards can be electrically noisy environments, and care
must be taken to protect the analog inputs from noise, particu-
larly when measuring the very small voltages from a remote
diode sensor. The following precautions should be taken:
1. Place the ADM1022 as close as possible to the remote sens-
ing 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 recom-
mended.
10MIL
10MIL
10MIL
10MIL
10MIL
10MIL
10MIL
GND
D+
D–
GND
Figure 13. Arrangement of Signal Tracks
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 1
°C
corresponds to about 200
µV, and thermocouple voltages are
about 3
µV/oC of temperature difference. Unless there are
two thermocouples with a big temperature differential between
them, thermocouple voltages should be much less than 200
µV.
5. Place 0.1
µF bypass and 1000 pF input filter capacitors close
to the ADM1022.
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 a shielded
twisted pair such as Belden #8451 microphone cable. Con-
nect the twisted pair to D+ and D– and the shield to GND
close to the ADM1022. 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 C1
may be reduced or removed. In any case, the total shunt capaci-
tance should not exceed 1000 pF.
Cable resistance can also introduce errors. 1
Ω series resistance
introduces about 0.5
°C error.


Similar Part No. - ADM1022

ManufacturerPart #DatasheetDescription
logo
Analog Devices
ADM1020 AD-ADM1020 Datasheet
132Kb / 12P
   8-Lead, Low-Cost, System Temperature Monitor
REV. 0
ADM1020AR-REEL AD-ADM1020AR-REEL Datasheet
132Kb / 12P
   8-Lead, Low-Cost, System Temperature Monitor
REV. 0
ADM1020AR-REEL7 AD-ADM1020AR-REEL7 Datasheet
132Kb / 12P
   8-Lead, Low-Cost, System Temperature Monitor
REV. 0
ADM1021 AD-ADM1021 Datasheet
139Kb / 12P
   Low Cost Microprocessor System Temperature Monitor
REV. 0
ADM1021A AD-ADM1021A Datasheet
203Kb / 16P
   Low-Cost Microprocessor System Temperature Monitor
REV. D
More results

Similar Description - ADM1022

ManufacturerPart #DatasheetDescription
logo
Analog Devices
EVAL-ADM1028 AD-EVAL-ADM1028 Datasheet
216Kb / 9P
   Evaluation Board for PC Temperature Monitor and Fan Control ASIC
REV. PrA 05/2000
ADM1025 AD-ADM1025 Datasheet
164Kb / 16P
   Low-Cost PC Hardware Monitor ASIC
REV. A
logo
ON Semiconductor
ADM1025 ONSEMI-ADM1025 Datasheet
302Kb / 21P
   Low Cost PC Hardware Monitor ASIC
February 2008 ??Rev. P5
ADT7473 ONSEMI-ADT7473_16 Datasheet
624Kb / 73P
   Remote Thermal Monitor and Fan Control
November, 2016 ??Rev. 11
ADT7473 ONSEMI-ADT7473_15 Datasheet
627Kb / 73P
   Remote Thermal Monitor and Fan Control
April, 2015 ??Rev. 10
logo
Analog Devices
ADM1021 AD-ADM1021 Datasheet
139Kb / 12P
   Low Cost Microprocessor System Temperature Monitor
REV. 0
ADM1021A AD-ADM1021A Datasheet
203Kb / 16P
   Low-Cost Microprocessor System Temperature Monitor
REV. D
logo
ON Semiconductor
ADT7473 ONSEMI-ADT7473_11 Datasheet
1Mb / 74P
   dbCOOL Remote Thermal Monitor and Fan Control
October, 2011 ??Rev. 7
ADT7473 ONSEMI-ADT7473 Datasheet
1Mb / 74P
   dBCOOL Remote Thermal Monitor and Fan Control
April, 2009 ??Rev. 6
logo
Analog Devices
ADM1030 AD-ADM1030 Datasheet
278Kb / 28P
   Intelligent Temperature Monitor and PWM Fan Controller
REV. 0
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com