FM75M8 Fairchild Semiconductor, FM75M8 Datasheet - Page 8

• Manufacturer Part Number: FM75M8
• Description: TEMPERATURE SENSOR LV 8SOIC
• Manufacturer: Fairchild Semiconductor

Specifications of FM75M8

• Function: Temp Monitoring System (Sensor)
• Topology: ADC (Sigma Delta), Comparator, Register Bank
• Sensor Type: Internal
• Sensing Temperature: -40°C ~ 125°C
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Full Temp Accuracy: 4 C
• Digital Output - Bus Interface: I2C, SMBus
• Digital Output - Number Of Bits: 9 bit to 12 bit
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Description/function: Semiconductor
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Supply Current: 500 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

© 2006 Fairchild Semiconductor Corporation
FM75 Rev. 1.0.8
Registers
The FM75 contains the following five registers:
■
■
■
■
■
Command Register
The command register is a one-byte (8-bit) write-only
register. The data stored in the command register indi-
cates which of the other registers (temperature, configu-
ration, T
upcoming operation. The command register “points” to
the selected register, as shown in Figure 11.
The command register is illustrated in Figure 9. The P1
and P0 bits of the command register determine which
register is accessed, as shown in Table 2. The six Most
Significant Bits (MSBs) of the command register must
always be zero. Writing a one into any of these bits
causes the current operation to be terminated.
The command register retains pointer information
between operations; therefore, this register only needs
to be updated once for consecutive read operations from
the same register. All bits in the command register
default to zero at power-up.
Command Register
Temperature Register
Configuration Register
Over-Limit-Signal Temperature Register (T
Hysteresis Temperature Register (T
OS
, or T
HYST
) to read from or write to during an
SD A
Command Register
1-byte Write Only
Serial Interface
Command
( P ointer )
Data
SCL
HYST
)
Figure 5. Register Hierarchy
OS
Read/Write
)
Data
8
All of these registers can be accessed by the user via the
digital serial interface at any time (see Serial Interface
Operation for instructions). A detailed description of
these registers and their functions is provided in the fol-
lowing sections. A diagram of the register hierarchy is
shown in Figure 5.
Table 2. Register Assignments for Command
Bits P1 and P2
Register
Temperature Register
Configuration Register
T
T
HYST
OS
MSB
Register
0
Register
Figure 6. Command Register Format
Command Reg. = 00000010
Command Reg. = 00000011
0
Configuration Register
Temperature Register
Command Reg. = 00000001
Command Reg. = 00000000
2-byte Read/Write
2-byte Read/Write
T
1-byte Read/Write
2-byte Read Only
T
0
HYST
OS
Register
Register
0
0
0 P1 P0
P1
0
0
1
1
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LSB
P0
0
1
0
1