Datasheet

TCN75A
DS21935A-page 12 © 2005 Microchip Technology Inc.
4.3.3 TEMPERATURE HYSTERESIS
REGISTER (T
HYST
)
The TCN75A 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
TCN75A asserts an alert output (refer to
Section 4.3.4.3 “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 <0 1001 0110> in binary.
REGISTER 4-4: TEMPERATURE HYSTERESIS REGISTER (T
HYST
)
Upper Half:
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
Sign 2
6
°C/bit 2
5
°C/bit 2
4
°C/bit 2
3
°C/bit 2
2
°C/bit 2
1
°C/bit 2
0
°C/bit
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/bit 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