LM74CIMX-3 National Semiconductor, LM74CIMX-3 Datasheet - Page 10

• Manufacturer Part Number: LM74CIMX-3
• Description: IC TEMP SENSOR DGTL 8-SOIC
• Manufacturer: National Semiconductor

Specifications of LM74CIMX-3

• Function: Temp Monitoring System (Sensor)
• Topology: ADC (Sigma Delta), Register Bank
• Sensor Type: Internal
• Sensing Temperature: -55°C ~ 150°C
• Output Type: MICROWIRE™, SPI™
• Output Alarm: No
• Output Fan: No
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -55°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: LM74CIMX-3TR

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1.5 INTERNAL REGISTER STRUCTURE
The LM74 has three registers, the temperature register, the
configuration register and the manufacturer's/device identifi-
1.5.1 Configuration Register
(Selects shutdown or continuous conversion modes):
(Write Only):
D0–D15 set to XX FF hex enables shutdown mode.
D0–D15 set to 00 00 hex sets Continuous conversion mode.
Note: setting D0-D15 to any other values may place the LM74 into a manufacturer's test mode, upon which the LM74 will stop
responding as described. These test modes are to be used for National Semiconductor production testing only. See Section 1.2
Serial Bus Interface for a complete discussion.
1.5.2 Temperature Register (after power-up, before first complete temperature conversion)
(Read Only):
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2–D15: Power-on Reset (POR) values.
1.5.3 Temperature Register (after completion of first temperature conversion)
(Read Only):
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2: High.
D3–D15: Temperature Data. One LSB = 0.0625°C. Two's complement format.
1.5.4 Manufacturer's Device ID Register
(Read Only):
D0–D1: Undefined. TRI-STATE will be output on SI/0.
D2–D15: Manufacturer's/Device ID Data. This register is accessed whenever the LM74 is in shutdown mode.
MSB
D15
D15
D15
D15
X
1
1
Bit 11 Bit 10
D14
D14
D14
D14
X
1
0
D13
D13
D13
D13
X
1
0
Bit 9
D12
D12
D12
D12
X
1
0
Bit 8
D11
D11
D11
D11
X
1
0
Bit 7
D10
D10
D10
D10
X
1
0
Bit 6
D9
D9
D9
D9
X
1
0
Bit 5
D8
D8
D8
D8
X
1
0
10
Bit 4
D7
D7
D7
D7
0
0
cation register. The temperature and manufacturer's/device
identification registers are read only. The configuration regis-
ter is write only.
Bit 3
D6
D6
D6
D6
0
0
Bit 2
D5
D5
D5
D5
0
0
Bit 1
D4
D4
D4
D4
Shutdown
0
0
LSB
D3
D3
D3
D3
0
0
D2
D2
D2
D2
0
1
0
D1
D1
D1
D1
X
X
X
D0
D0
D0
D0
X
X
X