MAX6682 Maxim Integrated Products, MAX6682 Datasheet - Page 7

• Manufacturer Part Number: MAX6682
• Description: Thermistor-to-Digital Converter
• Manufacturer: Maxim Integrated Products

sider a 10kΩ (at +25°C) NTC thermistor in series with a
5110Ω resistor operating at +40°C with a constant 5V
bias. If it is one of the standard thermistors in Table 2,
its resistance is 5325Ω at this temperature. The power
dissipated in the thermistor is:
This thermistor would therefore have a self-heating
error at +40°C of 1.22°C. Because the MAX6682 uses a
small reference voltage and energizes the thermistor
less than 2% of the time, the self-heating of the thermis-
tor under the same conditions when used with the
MAX6682 is only:
Table 3. Temperature vs. Digital Output for Standard Thermistor with R
*Assumes V R+ = 1.220V.
Figure 5. Serial Interface Timing
SCK
CS
SO
t
DV
TEMPERATURE
THERMISTOR
(5)
(1.22)
=1.46µW, or only about 0.0015° (self-heating
error)
+75.000
+70.000
+60.000
+50.000
+40.000
+30.000
+25.000
+20.000
+10.000
2
-5.000
(5325) / (5325 + 5110)
(°C)
0
MSB
B10
2
1
(5325)(0.02) / (5325 + 5110)
t
CSS
_______________________________________________________________________________________
B9
B8
STANDARD THERMISTOR
AND R
2
V
= 1.22mW
REXT
B7
t
DO
Thermistor-to-Digital Converter
EXT
946.0
908.6
820.6
715.7
597.4
473.5
412.6
354.1
249.2
165.1
131.5
(mV) WITH
= 5110Ω*
2
B6
B5
t
CH
B4
DECIMAL VALUE OF D
Table 2. Standard Thermistors
(USING 1LSB = 0.125°C)
t
MANUFACTURER
Betatherm
Dale
Thermometrics
CL
B3
54.875
47.875
39.625
15.750
11.125
-3.750
-6.375
57.75
30.25
2.875
20.5
B2
C100Y103J www.thermometrics.com
OUT
1M1002
10K3A1
B1
PART
t
TR
LSB
B0
www.betatherm.com
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dale/main.html
EXT
001 1100 1110
001 1011 0111
001 0111 1111
001 0011 1101
000 1111 0010
000 1010 0100
000 0111 1110
000 0101 1001
000 0001 0111
111 1110 0010
111 1100 1101
D
= 5110Ω
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