TCN75A_1 Datasheet, PDF (16/40 Pages) Microchip Technology – 2-Wire Serial Temperature Sensor

TCN75A
5.3.1 AMBIENT TEMPERATURE
REGISTER (T_A)
The TCN75A has a 16-bit read-only Ambient
Temperature register that contains 9-bit to 12-bit
temperature data. (0.5°C to 0.0625°C resolutions,
respectively). This data is formatted in two’s
complement. The bit assignments, as well as the
corresponding resolution, is shown in the register
assignment below.
The refresh rate of this register depends on the
selected ADC resolution. It takes 30 ms (typical) for
9-bit data and 240 ms (typical) for 12-bit data. Since
this register is double-buffered, the user can read the
register while the TCN75A performs Analog-to-Digital
conversion in the background. The decimal code to
ambient temperature conversion is shown in
Equation 5-2:
EQUATION 5-2:
Where:
T_A = Code  2^–4
T_A = Ambient Temperature (°C)
Code = TCN75A output in decimal
REGISTER 5-2:
Upper Half:
R-0
Sign
bit 15
AMBIENT TEMPERATURE REGISTER (T_A) — ADDRESS <0000 0000>b
R-0
2⁶ °C
R-0
2⁵ °C
R-0
2⁴ °C
R-0
2³ °C
R-0
2² °C
R-0
2¹ °C
R-0
2⁰ °C
bit 8
Lower Half:
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
2^-1 °C/bit
2^-2 °C
2^-3 °C
2^-4 °C
0
0
0
0
bit 7
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
Note 1: When the 0.5°C, 0.25°C or 0.125°C resolutions are selected, bit 6, bit 7 or bit 8 will remain clear <0>,
respectively.
DS21935D-page 16
 2010 Microchip Technology Inc.