DS18B20-PAR-TU0026R 데이터 시트보기 (PDF) - Maxim Integrated
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DS18B20-PAR-TU0026R Datasheet PDF : 19 Pages
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DS18B20-PAR
resolution, bits 1 and 0 are undefined, and for 9-bit resolution bits 2, 1 and 0 are undefined. Table 2 gives
examples of digital output data and the corresponding temperature reading for 12-bit resolution
conversions.
TEMPERATURE REGISTER FORMAT Figure 3
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
LS Byte
23
22
21
20
2-1
2-2
2-3
2-4
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
MS Byte S
S
S
S
S
26
25
24
TEMPERATURE/DATA RELATIONSHIP Table 2
TEMPERATURE DIGITAL OUTPUT DIGITAL OUTPUT
(Binary)
(Hex)
+85°C*
0000 0101 0101 0000
0550h
+25.0625°C
0000 0001 1001 0001
0191h
+10.125°C
0000 0000 1010 0010
00A2h
+0.5°C
0000 0000 0000 1000
0008h
0°C
0000 0000 0000 0000
0000h
-0.5°C
1111 1111 1111 1000
FFF8h
-10.125°C
1111 1111 0101 1110
FF5Eh
-25.0625°C
1111 1110 0110 1111
FE6Fh
-55°C
1111 1100 1001 0000
FC90h
*The power-on reset value of the temperature register is +85°C
OPERATION – ALARM SIGNALING
After the DS18B20-PAR performs a temperature conversion, the temperature value is compared to the
user-defined two’s complement alarm trigger values stored in the 1-byte TH and TL registers (see Figure
4). The sign bit (S) indicates if the value is positive or negative: for positive numbers S = 0 and for
negative numbers S = 1. The TH and TL registers are nonvolatile (EEPROM) so they will retain data
when the device is powered down. TH and TL can be accessed through bytes 2 and 3 of the scratchpad as
explained in the MEMORY section of this datasheet.
TH AND TL REGISTER FORMAT Figure 4
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
S
26
25
24
23
22
21
20
Only bits 11 through 4 of the temperature register are used in the TH and TL comparison since TH and TL
are 8-bit registers. If the result of a temperature measurement is higher than or equal to TH or lower than
or equal to TL, an alarm condition exists and an alarm flag is set inside the DS18B20-PAR. This flag is
updated after every temperature measurement; therefore, if the alarm condition goes away, the flag will
be turned off after the next temperature conversion.
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