DS75LV Просмотр технического описания (PDF) - Maxim Integrated
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DS75LV Datasheet PDF : 14 Pages
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DS75LV
Digital Thermometer and Thermostat
Detailed Description
Measuring Temperature
The DS75LV measures temperature using a bandgap
temperature sensing architecture. An on-board delta-sigma
analog-to-digital converter (ADC) converts the measured
temperature to a digital value that is calibrated in degrees
centigrade; for Fahrenheit applications a lookup table or
conversion routine must be used. The DS75LV is factory-
calibrated and requires no external components to measure
temperature.
At power-up the DS75LV immediately begins converting
temperature to a digital value. The resolution of the
digital output data is user-configurable to 9, 10, 11, or
12 bits, corresponding to temperature increments of
0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively, with
9-bit default resolution at power-up. The resolution is
controlled via the R0 and R1 bits in the configuration
register as explained in the Configuration Register
section. Note that the conversion time doubles for each
additional bit of resolution.
After each temperature measurement and analog-to-digital
conversion, the DS75LV stores the temperature as a 16-bit
two’s complement number in the 2-byte temperature register
(see Figure 3). The sign bit (S) indicates if the temperature
is positive or negative: for positive numbers S = 0 and for
negative numbers S = 1. The most recently converted digital
measurement can be read from the temperature register at
any time. Since temperature conversions are performed in
the background, reading the temperature register does not
affect the operation in progress.
Bits 3 through 0 of the temperature register are hardwired
to 0. When the DS75LV is configured for 12-bit resolution,
the 12 MSbs (bits 15 through 4) of the temperature register
contain temperature data. For 11-bit resolution, the 11
MSbs (bits 15 through 5) of the temperature register
contain data, and bit 4 reads out as 0. Likewise, for 10-bit
resolution, the 10 MSbs (bits 15 through 6) contain data,
and for 9-bit the 9 MSbs (bits 15 through 7) contain data,
and all unused LSbs contain 0s. Table 1 gives examples
of 12-bit resolution digital output data and the corresponding
temperatures.
Table 1. 12-Bit Resolution Temperature/
Data Relationship
TEMPERATURE
(°C)
+125
+25.0625
+10.125
+0.5
0
-0.5
-10.125
-25.0625
-55
DIGITAL OUTPUT
(BINARY)
0111 1101 0000 0000
0001 1001 0001 0000
0000 1010 0010 0000
0000 0000 1000 0000
0000 0000 0000 0000
1111 1111 1000 0000
1111 0101 1110 0000
1110 0110 1111 0000
1100 1001 0000 0000
DIGITAL
OUTPUT
(HEX)
7D00h
1910h
0A20h
0080h
0000h
FF80h
F5E0h
E6F0h
C900h
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
MS Byte
S
26
25
24
23
22
21
20
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
LS Byte
2-1
2-2
2-3
2-4
0
0
0
0
Figure 3. Temperature, TOS, and THYST Register Format
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