MCP9802 Microchip Technology Inc., MCP9802 Datasheet - Page 10

• Manufacturer Part Number: MCP9802
• Description: 2-wire High-accuracy Temperature Sensor
• Manufacturer: Microchip Technology Inc.

MCP9800/1/2/3
4.3.1
The MCP9800/1/2/3 has a 16-bit read-only ambient
temperature register
temperature data. 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 (typ.) for 9-bit
data and 240 ms (typ.) for 12-bit data. Since this
register is double-buffered, the user can read the
register while the MCP9800/1/2/3 performs analog-to-
REGISTER 4-2:
TABLE 4-1:
DS21909B-page 10
Note 1:
Upper Half:
bit 15
Legend:
R = Readable bit
- n = Value at POR
+25.4375°C
Note:
+125°C
+0.5°C
Sign
R-0
9-Bit
2:
3:
‘u’ represents unused bits. The MCP9800/1/2/3 clears <0> the unused bits.
This data is in two’s complement format, which indicates ambient temperature below 0°C.
Negative temperature magnitude in Hexadecimal. This conversion is done by complimenting each binary bit and
adding 1.
AMBIENT TEMPERATURE
REGISTER (T
When the 9-bit, 10-bit or 11-bit resolutions are selected, bit 6, bit 7 or bit 8 will remain clear <0>,
respectively.
2
+25.4375°C
6
Ambient Temperature
+0.25°C
+125°C
R-0
10-Bit
°C/bit
AMBIENT TEMPERATURE TO CODE CONVERSION
Lower Half:
bit 7
2
-1
(T
R-0
AMBIENT TEMPERATURE REGISTER (T
°C/bit
A
)
0°C
that contains 9-bit to 12-bit
A
2
)
+25.4375°C
5
+0.125°C
+125°C
R-0
°C/bit
11-Bit
2
-2
R-0
°C/bit
W = Writable bit
‘1’ = Bit is set
2
+25.4375°C
–25.4375°C
4
+0.0625°C
–0.0625°C
R-0
°C/bit
+125°C
12-Bit
–55°C
2
-3
R-0
°C/bit
2
3
1111 1111 1111 uuuu
0111 1101 0uuu uuuu
R-0
°C/bit
0001 1001 0uuu uuuu
0000 0000 1uuu uuuu
0111 1101 00uu uuuu
0001 1001 01uu uuuu
0000 0000 01uu uuuu
0111 1101 000u uuuu
0001 1001 011u uuuu
0000 0000 001u uuuu
0111 1101 0000 uuuu
0001 1001 0111 uuuu
0000 0000 0001 uuuu
0000 0000 0000 uuuu
1110 0110 1001 uuuu
1100 1001 0000 uuuu
2
-4
R-0
°C/bit
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
digital conversion in the background. The decimal code
to ambient temperature conversion is shown in
Equation 4-2:
EQUATION 4-2:
Where:
Binary
2
2
R-0
°C/bit
n
T
Code= MCP980X output in decimal
A
A
)
= -1, -2, -3 and -4 for 9-bit, 10-bit, 11-bit
= Ambient Temperature (°C)
R-0
0
and 12-bit resolution, respectively
(Table 4-1)
2
1
Code
(2)
(1)
R-0
°C/bit
T
Hexadecimal
A
R-0
=
001
 2004 Microchip Technology Inc.
0
0CB
0FA
3E8
7D0
032
001
1F4
065
001
001
197
001
000
197
370
Code 2
2
x = Bit is unknown
(3)
0
R-0
°C/bit
bit 8
n
R-0
0
Decimal
1000
2000
-407
-880
250
500
101
203
407
50
-1
1
1
1
1
0
+25.4375
-25.4375
+25.375
+0.0625
-0.0625
R-0
+25.25
+0.125
+0.25
+125
+125
+125
+125
0
+0.5
(°C)
+25
-55
T
0
bit 0
A