Datasheet
LM75B All information provided in this document is subject to legal disclaimers. © NXP B.V. 2015. All rights reserved.
Product data sheet Rev. 6.1 — 6 February 2015 9 of 37
NXP Semiconductors
LM75B
Digital temperature sensor and thermal watchdog
7.4.3 Temperature register
The Temperature register (Temp) holds the digital result of temperature measurement or
monitor at the end of each analog-to-digital conversion. This register is read-only and
contains two 8-bit data bytes consisting of one Most Significant Byte (MSByte) and one
Least Significant Byte (LSByte). However, only 11 bits of those two bytes are used to store
the Temp data in two’s complement format with the resolution of 0.125 C. Table 9
shows
the bit arrangement of the Temp data in the data bytes.
When reading register Temp, all 16 bits of the two data bytes (MSByte and LSByte) are
provided to the bus and must be all collected by the controller to complete the bus
operation. However, only the 11 most significant bits should be used, and the 5 least
significant bits of the LSByte are zero and should be ignored. One of the ways to calculate
the Temp value in C from the 11-bit Temp data is:
1. If the Temp data MSByte bit D10 = 0, then the temperature is positive and Temp value
(C) = +(Temp data) 0.125 C.
2. If the Temp data MSByte bit D10 = 1, then the temperature is negative and
Temp value (C) = (two’s complement of Temp data) 0.125 C.
Examples of the Temp data and value are shown in Table 10
.
B2 OS_POL R/W OS polarity selection
0* OS active LOW
1 OS active HIGH
B1 OS_COMP_INT R/W OS operation mode selection
0* OS comparator
1 OS interrupt
B0 SHUTDOWN R/W device operation mode selection
0* normal
1 shutdown
Table 8. Conf register
…continued
Legend: * = default value.
Bit Symbol Access Value Description
Table 9. Temp register
MSByte LSByte
7654321076543210
D10D9D8D7D6D5D4D3D2D1D0 X X X X X
Table 10. Temp register value
11-bit binary
(two’s complement)
Hexadecimal value Decimal value Value
011 1111 1000 3F8 1 016 +127.000 C
011 1111 0111 3F7 1 015 +126.875 C
011 1111 0001 3F1 1 009 +126.125 C
011 1110 1000 3E8 1000 +125.000 C
000 1100 1000 0C8 200 +25.000 C
000 0000 0001 001 1 +0.125 C