SNIS217C december 2020 – may 2023 TMP139
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
All temperature result and limit registers are eleven bit values stored in two consecutive registers. The low byte register comes first followed by the high byte register as shown in Table 7-1 for the register map. The data is represented as a 11-bit signed number with the most significant bit for the temperature format being the signed bit. Each of the temperature value bits is assigned a weight which can be used to compute the temperature value. All unused bits read as 0 and any attempt to write a unused bit shall have no effect. The resolution of the temperature result and limit registers is always 0.25°C and the values can range from –255.75°C to +255.75°C, even though the recommended operating range is from –40°C to +125°C.
REGISTER BYTE | BIT 7 | BIT 6 | BIT 5 | BIT 4 | BIT 3 | BIT 2 | BIT 1 | BIT 0 |
---|---|---|---|---|---|---|---|---|
Low Byte | 8 | 4 | 2 | 1 | 0.5 | 0.25 | RSVD = 0 | RSVD = 0 |
High Byte | RSVD = 0 | RSVD = 0 | RSVD = 0 | Sign | 128 | 64 | 32 | 16 |
The Table 7-2 shows examples of the temperature register read and its corresponding conversion in°C.
TEMPERATURE (°C) | HIGH BYTE | LOW BYTE |
---|---|---|
+255.75 | 0000 1111 | 1111 1100 |
+125 | 0000 0111 | 1101 0000 |
+95 | 0000 0101 | 1111 0000 |
+85 | 0000 0101 | 0101 0000 |
+75 | 0000 0100 | 1011 0000 |
+1 | 0000 0000 | 0001 0000 |
+0.25 | 0000 0000 | 0000 0100 |
0 | 0000 0000 | 0000 0000 |
–0.25 | 0001 1111 | 1111 1100 |
–1 | 0001 1111 | 1111 0000 |
–25 | 0001 1110 | 0111 0000 |
–40 | 0001 1101 | 1000 0000 |
–255.75 | 0001 0000 | 0000 0000 |