Datasheet

MCP9800/1/2/3
DS21909D-page 20  2010 Microchip Technology Inc.
5.3.3 TEMPERATURE HYSTERESIS
REGISTER (T
HYST
)
The MCP9800/1/2/3 has a 16-bit read/write
Temperature Hysteresis register that contains a 9-bit
data in two’s compliment format. This register is used
to set a hysteresis for the T
SET
limit. Therefore, the data
represents a minimum temperature limit. If the ambient
temperature drifts below the specified limit, the
MCP9800/1/2/3 asserts an alert output (refer to
Section 5.3.4.3 “ALERT Output Configuration”).
This register uses the nine Most Significant bits (MSbs)
and all other bits are “don’t cares”.
The power-up default value of T
HYST
register is 75°C,
or <0100 1011 0>b in binary.
REGISTER 5-4: TEMPERATURE HYSTERESIS REGISTER (T
HYST
) – ADDRESS <0000 0010>b
Upper Half:
R/W-0 R/W-1 R/W-0 R/W-0 R/W-1 R/W-0 R/W-1 R/W-1
Sign 2
6
°C 2
5
°C 2
4
°C 2
3
°C 2
2
°C 2
1
°C 2
0
°C
bit 15 bit 8
Lower Half:
R/W-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0
2
-1
°C 0 0 0 0 0 0 0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown