Datasheet

LM81
SNAS011E –JUNE 1999–REVISED FEBRUARY 2002 www.ti.com
TEMPERATURE DATA FORMAT
Temperature data can be read from the Temperature, T
HIGH
setpoint, T
HIHYST
setpoint, T
LOW
setpoint, T
C
setpoint
and T
HYST
Offset registers; and written to the T
HIGH
setpoint, T
HIHYST
, T
LOW
setpoint, T_CRIT setpoint and T
HYST
offset registers. T
HIGH
setpoint, T
LOW
setpoint, T_CRIT setpoint temperature data is represented by an 8-bit, two’s
complement word with an LSB (Least Significant Bit) equal to 1˚C:
Temperature Digital Output
Binary Hex
+125˚C 0111 1101 7Dh
+25˚C 0001 1001 19h
+1.0˚C 0000 0001 01h
+0˚C 0000 0000 00h
−1.0˚C 1111 1111 FFh
−25˚C 1110 0111 E7h
−40˚C 1101 1000 D8h
By default Temperature Register data is represented by a 9-bit two’s complement digital word with the LSB
having a resolution of 0.5˚C:
Temperature Digital Output
Binary Hex
+125˚C 0 1111 1010 0 FAh
+25˚C 0 0011 0010 0 32h
+1.5˚C 0 0000 0011 0 03h
+0˚C 0 0000 0000 0 00h
−0.5˚C 1 1111 1111 1 FFh
−25˚C 1 1100 1110 1 CEh
−40˚C 1 1011 0000 1 B0h
In the extended mode temperature Register data can also be represented by a 12-bit two’s complement digital
word with an LSB of 0.0625˚C:
Temperature Digital Output
Binary Hex
+125˚C 0111 1100 0000 7 D0h
+25˚C 0001 1001 0000 1 90h
+1.0˚C 0000 0001 0000 0 10h
+0.0625˚C 0000 0000 0001 0 01h
0˚C 0000 0000 0000 0 00h
−0.0625˚C 1111 1111 1111 F FFh
−1.0˚C 1111 1111 0000 F F0h
−25˚C 1110 0111 0000 E 70h
−40˚C 1101 1000 0000 D 80h
T
HYST
Offset temperature data is represented by a 3-bit word with an LSB (Least Significant Bit) equal to 1˚C.
TEMPERATURE INTERRUPTS
INT and T_CRIT_A outputs are provided for temperature interrupt. Temperature interrupts have a normal and an
extended option of operation. Each option has three different modes of operation: Repetitive Interrupt, One-Time
Interrupt and Comparator.
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