FM75 Fairchild Semiconductor, FM75 Datasheet - Page 9

• Manufacturer Part Number: FM75
• Description: Low Voltage 2-Wire Digital Temperature Sensor with Thermal Alarm
• Manufacturer: Fairchild Semiconductor

.
PRODUCT SPECIFICATION
Over-Limit-Signal Temperature Register (T
The T
that stores the user-programmable upper trip-point
temperature for the thermal alarm in two’s-complement
format. At power-up this register defaults to 80°C
(i.e., 0101 0000 0000 0000).
The format of the TOS register is identical to that of the
Temperature Register (see Figure 6). The 4 LSBs of the T
Register are hardwired to zero, so data written to these
register bits will be ignored. The MSB position of the T
Register contains the sign bit for the digital temperature and
bit 14 contains the temperature MSB.
The resolution setting for the T-to-D conversion determines
how many bits of the T
alarm. For example, for 9-bit conversions the trip-point
temperature is defined by the 9 MSBs of the T
and all remaining bits are “don’t cares.”
REV. 1.0.4 10/3/02
OS
Register is a two-byte (16-bit) read/write register
OS
Register are used by the thermal
MSB
Figure 6. T
SB
SB = Two’s complement sign bit
TMSB = Temperature MSB
T = Temperature data
9-bit LSB = Temperature LSB for 9-bit conversions
10-bit LSB = Temperature LSB for 10-bit conversions
11-bit LSB = Temperature LSB for 11-bit conversions
12-bit LSB = Temperature LSB for 12-bit conversions
9-bit
LSB
TMSB
7
14
OS
HYST
10-bit
LSB
register,
6
13
T
Register and T
11-bit
OS
LSB
OS
5
12
T
OS
)
12-bit
LSB
4
11
T
Hysteresis Temperature Register (T
The T
register that stores the user programmable lower trip-point
temperature for the thermal alarm in two’s-complement
format. At power-up this register defaults to 75°C (i.e., 0100
1011 0000 0000).
The T
this register is the same as that of the Temperature Register.
The 4 LSBs of the T
data written to these bits is ignored.
The resolution setting for the T-to-D conversion determines
how many bits of the T
alarm. For example, for 9-bit conversions the hysteresis
temperature is defined by the 9 MSBs of the T
and all remaining bits are “don’t cares.”
0
3
OS
10
T
HYST
HYST
Register Format
0
2
T
9
Register is a two-byte (16-bit) read/write
register is illustrated in Figure 6. The format of
0
1
T
8
HYST
LSB
0
HYST
register are hardwired to zero, so
Register are used by the thermal
HYST
HYST
Register,
)
FM75
9