LM80 National Semiconductor, LM80 Datasheet - Page 16

• Manufacturer Part Number: LM80
• Description: Serial Interface ACPI-Compatible Microprocessor System Hardware Monitor
• Manufacturer: National Semiconductor

www.national.com
Functional Description
7.0 TEMPERATURE MEASUREMENT SYSTEM
The LM80 bandgap type temperature sensor and ADC per-
form 9-bit or a 12-bit two’s-complement conversions of the
temperature. An 8-bit digital comparator is also incorporated
that compares the readings to the user-programmable Hot
and Overtemperature setpoints, and Hysteresis values.
(Non-Linear Scale for Clarity)
(Non-Linear Scale for Clarity)
FIGURE 9. 12-bit Temperature-to-Digital Transfer
FIGURE 8. 9-bit Temperature-to-Digital Transfer
Function
Function
(Continued)
DS100040-20
DS100040-16
16
7.1 Temperature Data Format
Temperature data can be read from the Temperature, T
T
T
point, T
ture data is represented by an 8-bit, two’s complement word
with an LSB (Least Significant Bit) equal to 1˚C:
hot hyst
hot
Temperature
, T
+125˚C
+1.0˚C
−1.0˚C
+25˚C
−25˚C
−55˚C
, T
hot hyst
+0˚C
hot hyst
os
and T
, T
set point, T
os
os hyst
and T
setpoint registers; and written to the
os hyst
0111 1101
0001 1001
0000 0001
0000 0000
1111 1111
1110 0111
1100 1001
os
Binary
set point and T
Digital Output
setpoint registers. T
os hyst
Hex
7Dh
C9h
19h
01h
00h
FFh
E7h
tempera-
hot
hot
set
,