THMC50_08 Datasheet, PDF (20/34 Pages) Texas Instruments – REMOTE/LOCAL TEMPERATURE MONITOR AND FAN CONTROLLER WITH SMBus INTERFACE

THMC50
REMOTE/LOCAL TEMPERATURE MONITOR AND
FAN CONTROLLER WITH SMBus INTERFACE
SLIS090 – JULY 1999
PRINCIPLES OF OPERATION
THERM operation (continued)
Default or
Programmable
THERM Limit
5°C Hysteresis
Temperature
THERM
5°C
THERM goes low after three
consecutive readings that exceed
the trip point, and stays low until
three consecutive readings that
are at least 5°C below the trip
point.
External
THERM
input
Programmed
FAN_SPD/NTEST_IN
value
0xFF
FAN_SPD/NTEXT_IN goes to full
scale (0xFF) whenever THERM is
asserted internally or externally,
returns to previously programmed
value once THERM is cleared.
0xFF
FAN_OFF
FAN_OFF
commanded
low by user
FAN_OFF floats
high due to THERM
Figure 16. Examples of THMC50 THERM Event Behavior
temperature data format
Temperature data can be read from the remote diode temperature register or the ambient temperature register
in the value RAM (locations 0x26 and 0x27, respectively). Temperature data is represented by an 8-bit, 2s
complement word with an LSB equal to 1°C as shown in Table 2.
Table 2. Temperature Data Format
TEMPERATURE
125°C
25°C
1°C
0°C
–1°C
–25°C
–55°C
DIGITAL OUTPUT
BINARY
HEX
0111 1101
0x7D
0001 1001
0x19
0000 0001
0x01
0000 0000
0x00
1111 1111
0xFF
1110 0111
0xE7
1100 1001
0xC9
20
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