Datasheet
MAX31850/MAX31851
Cold-Junction Compensated, 1-Wire
Thermocouple-to-Digital Converters
13Maxim Integrated
Configuration Register
Byte 4 of Scratchpad contains the configuration reg-
ister, which is organized as shown in Configuration
Register Format. The configuration register allows the
user to read the programmed value of the address pins.
The AD[3:0] bits report the pin-programmed location
information. Pins connected to DQ are reported with
logic 1, and pins connected to GND are reported as
logic 0. Pins connected to DQ or GND through a resis-
tor are valid logic 1s or logic 0s if the resistor is less
than 10kI. Unconnected or high-impedance ( > 10kI)
connections are indeterminate. Bits [7:4] are reserved
for internal use and cannot be overwritten; they return
a 1 when read.
Table 2. Temperature Data Format
Configuration Register Format
Note: Bits [3:0] are programmed through the four location programming address pins, AD[3:0]. Reading the configuration register
provides location information on up to 16 individual devices.
Table 3. Thermocouple Temperature Data
Format
Table 4. Internal (Cold-Junction)
Temperature Data Format
Cold-Junction-Compensated Thermocouple Temperature Data (Bytes 0 and 1)
BIT 7 6 5 4 3 2 1 0
LSByte (Scratchpad
Byte 0)
2
3
2
2
2
1
2
0
2
-1
2
-2
Reserved 1 = Fault
BIT 15 14 13 12 11 10 9 8
MSByte (Scratchpad
Byte 1)
Sign 2
10
2
9
2
8
2
7
2
6
2
5
2
4
Internal (Cold-Junction) Temperature Data (Bytes 2 and 3)
BIT 7 6 5 4 3 2 1 0
LSByte (Scratchpad
Byte 2)
2
-1
2
-2
2
-3
2
-4
Reserved
1 = Short
to V
DD
1 = Short
to GND
1 = Open
Circuit
BIT 15 14 13 12 11 10 9 8
MSByte (Scratchpad
Byte 3)
Sign 2
6
2
5
2
4
2
3
2
2
2
1
2
0
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
— — — — AD3 AD2 AD1 AD0
TEMPERATURE
(NC)
DIGITAL OUTPUT
(D[31:18])
+1600.00 0110 0100 0000 00
+1000.00 0011 1110 1000 00
+100.75 0000 0110 0100 11
+25.00 0000 0001 1001 00
0.00 0000 0000 0000 00
-0.25 1111 1111 1111 11
-1.00 1111 1111 1111 00
-250.00 1111 0000 0110 00
TEMPERATURE
(NC)
DIGITAL OUTPUT
(D[15:4])
+127.0000 0111 1111 0000
+100.5625 0110 0100 1001
+25.0000 0001 1001 0000
0.0000 0000 0000 0000
-0.0625 1111 1111 1111
-1.0000 1111 1111 0000
-20.0000 1110 1100 0000
-55.0000 1100 1001 0000