LM75ADP/DG,118 NXP Semiconductors, LM75ADP/DG,118 Datasheet - Page 8

• Manufacturer Part Number: LM75ADP/DG,118
• Description: IC TEMP SENSOR DIGITAL 8TSSOP
• Manufacturer: NXP Semiconductors

Specifications of LM75ADP/DG,118

• Function: Temp Sensor, Watchdog
• Topology: ADC (Sigma Delta), Comparator, Oscillator, Register Bank
• Sensor Type: Internal
• Sensing Temperature: -55°C ~ 125°C
• Output Type: I²C™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 2.8 V ~ 5.5 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

NXP Semiconductors
LM75A_4
Product data sheet
7.4.4 Overtemperature shutdown threshold (Tos) and hysteresis (Thyst) registers
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:
Examples of the Temp data and value are shown in
Table 10.
Obviously, for 9-bit Temp data application in replacing the industry standard LM75, just
use only 9 MSB bits of the two bytes and disregard 7 LSB of the LSByte. The 9-bit Temp
data with 0.5 C resolution of the LM75A is defined exactly in the same way as for the
standard LM75 and it is here similar to the Tos and Thyst registers.
These two registers, are write/read registers, and also called set-point registers. They are
used to store the user-defined temperature limits, called overtemperature shutdown
threshold (Tos) and hysteresis temperature (Thyst), for the device watchdog operation. At
the end of each conversion the Temp data will be compared with the data stored in these
two registers in order to set the state of the device OS output; see
Each of the set-point registers contains two 8-bit data bytes consisting of one MSByte and
one LSByte the same as register Temp. However, only 9 bits of the two bytes are used to
store the set-point data in 2’s complement format with the resolution of 0.5 C.
and
Notice that because only 9-bit data are used in the set-point registers, the device uses
only the 9 MSB of the Temp data for data comparison.
11-bit binary
(2’s complement)
011 1111 1000
011 1111 0111
011 1111 0001
011 1110 1000
000 1100 1000
000 0000 0001
000 0000 0000
111 1111 1111
111 0011 1000
110 0100 1001
110 0100 1000
1. If the Temp data MSByte bit D10 = 0, then the temperature is positive and Temp value
2. If the Temp data MSByte bit D10 = 1, then the temperature is negative and
( C) = +(Temp data)
Temp value ( C) = (2’s complement of Temp data)
Table 12
Temp register value
show the bit arrangement of the Tos data and Thyst data in the data bytes.
Hexadecimal value
3F8
3F7
3F1
3E8
0C8
001
000
7FF
738
649
648
Rev. 04 — 10 July 2007
0.125 C.
Digital temperature sensor and thermal watchdog
Decimal value
1016
1015
1009
1000
200
1
0
1
200
439
440
Table
0.125 C.
10.
Section
Value
+127.000 C
+126.875 C
+126.125 C
+125.000 C
+25.000 C
+0.125 C
0.000 C
0.125 C
25.000 C
54.875 C
55.000 C
© NXP B.V. 2007. All rights reserved.
LM75A
7.1.
Table 11
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