LM73

SNIS141D – OCTOBER 2005 – REVISED MAY 2009

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Table 3. 13-bit (12-bit plus Sign)

Temperature

Digital Output

Binary

Hex

+150°C

0100 1011 0000 0000

4B00h

+25°C

0000 1100 1000 0000

0C80h

+1°C

0000 0000 1000 0000

0080h

+0.0625°C

0000 0000 0000 1000

0008h

0°C

0000 0000 0000 0000

0000h

−0.0625°C

1111 1111 1111 1000

FFF8h

−1°C

1111 1111 1000 0000

FF80h

−25°C

1111 0011 1000 0000

F380h

−40°C

1110 1100 0000 0000

EC00h

Table 4. 14-bit (13-bit plus Sign)

Temperature

Digital Output

Binary

Hex

+150°C

0100 1011 0000 0000

4B00h

+25°C

0000 1100 1000 0000

0C80h

+1°C

0000 0000 1000 0000

0080h

+0.03125°C

0000 0000 0000 0100

0004h

0°C

0000 0000 0000 0000

0000h

−0.03125°C

1111 1111 1111 1100

FFFCh

−1°C

1111 1111 1000 0000

FF80h

−25°C

1111 0011 1000 0000

F380h

−40°C

1110 1100 0000 0000

EC00h

SMBus INTERFACE

The LM73 operates as a slave on the SMBus. The SMBDAT line is bidirectional. The SMBCLK line is an input

only. The LM73 never drives the SMBCLK line and it does not support clock stretching.

The LM73 uses a 7-bit slave address. It is available in two versions. Each version can be configured for one of

three unique slave addresses, for a total of six unique address.

Part

Address

Device

Number

Pin

Address

LM73-0

Float

1001 000

Ground

1001 001

1001 010

LM73-1

Float

1001 100

Ground

1001 101

1001 110

The SMBDAT output is an open-drain output and does not have internal pull-ups. A “high” level will not be

observed on this pin until pull-up current is provided by some external source, typically a pull-up resistor. Choice

of resistor value depends on many system factors but, in general, the pull-up resistor should be as large as

possible without effecting the SMBus desired data rate. This will minimize any internal temperature reading

errors due to internal heating of the LM73.

The LM73 features an integrated low-pass filter on both the SMBCLK and the SMBDAT line. These filters

increase communications reliability in noisy environments.

data line. Once the SMBDAT is released high, the master may initiate an SMBus start.

10

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