EVAL-ADT7X20EBZ View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-ADT7X20EBZ' PDF : 25 Pages View PDF
ADT7320
TEMPERATURE DATA FORMAT
One LSB of the ADC corresponds to 0.0625°C in 13-bit mode or
0.0078°C in 16-bit mode. The ADC can theoretically measure a
temperature range of 255°C, but the ADT7320 is guaranteed to
measure a low value temperature limit of −40°C to a high value
temperature limit of +150°C. The temperature measurement
result is stored in the 16-bit temperature value register and is
compared with the high temperature limits stored in the TCRIT
setpoint register and the THIGH setpoint register. It is also compared
with the low temperature limit stored in the TLOW setpoint register.
Temperature data in the temperature value register, the TCRIT
setpoint register, the THIGH setpoint register, and the TLOW
setpoint register are represented by a 13-bit, twos complement
word. The MSB is the temperature sign bit. On power-up the three
LSBs, Bit 0 to Bit 2, are not part of the temperature conversion
result and are flag bits for TCRIT, THIGH, and TLOW. Table 5 shows
the 13-bit temperature data format without Bit 0 to Bit 2.
The number of bits in the temperature data-word can be extended
to 16 bits, twos complement by setting Bit 7 to 1 in the configuration
register (Register Address 0x01). When using a 16-bit temperature
data value, Bit 0 to Bit 2 are not used as flag bits and are instead
the LSB bits of the temperature value. The power-on default
setting has a 13-bit temperature data value.
Reading back the temperature from the temperature value register
requires a 2-byte read. Designers that use a 9-bit temperature
data format can still use the ADT7320 by ignoring the last four
LSBs of the 13-bit temperature value. These four LSBs are Bit 3
to Bit 6 in Table 5.
Table 5. 13-Bit Temperature Data Format
Temperature
Digital Output (Binary) Bits[15:3]
−40°C
1 1101 1000 0000
−25°C
1 1110 0111 0000
−0.0625°C
1 1111 1111 1111
0°C
0 0000 0000 0000
+0.0625°C
0 0000 0000 0001
+25°C
0 0001 1001 0000
+105°C
0 0110 1001 0000
+125°C
0 0111 1101 0000
+150°C
0 1001 0110 0000
Data Sheet
TEMPERATURE CONVERSION FORMULAS
16-Bit Temperature Data Format
Positive Temperature = ADC Code (dec)/128
Negative Temperature = (ADC Code (dec) − 65,536)/128
where ADC Code uses all 16 bits of the data byte, including the
sign bit.
Negative Temperature = (ADC Code (dec) − 32,768)/128
where the MSB is removed from the ADC code.
13-Bit Temperature Data Format
Positive Temperature = ADC Code (dec)/16
Negative Temperature = (ADC Code (dec) − 8192)/16
where ADC Code uses all 13 bits of the data byte, including the
sign bit.
Negative Temperature = (ADC Code (dec) − 4096)/16
where the MSB is removed from the ADC code.
10-Bit Temperature Data Format
Positive Temperature = ADC Code (dec)/2
Negative Temperature = (ADC Code (dec) − 1024)/2
where ADC Code uses all 10 bits of the data byte, including the
sign bit.
Negative Temperature = (ADC Code (dec) − 512)/2
where the MSB is removed from the ADC Code.
9-Bit Temperature Data Format
Positive Temperature = ADC Code (dec)
Negative Temperature = ADC Code (dec) − 512
where ADC Code uses all nine bits of the data byte, including
the sign bit.
Negative Temperature = ADC Code (dec) − 256
where the MSB is removed from the ADC Code.
Rev. 0 | Page 12 of 24
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