Datasheet

LM95245

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SNIS148G –OCTOBER 2007–REVISED MARCH 2013

SMBus INTERFACE

The LM95245 operates as a slave on the SMBus, so the SMBCLK line is an input and the SMBDAT line is

bidirectional. The LM95245 never drives the SMBCLK line and it does not support clock stretching. According to

SMBus specifications, the LM95245 has a 7-bit slave address. Three SMBus addresses can be selected by

connecting pin 6 (A0) to either Low, Mid-Supply or High voltages. The address selection table below shows two

sets of possible selections for the LM95245CIMM and the LM95245CIMM-1.

LM95245CIMM SMBus Device LM95245CIMM-1 SMBus

Address Device Address

State of the A0 Pin

HEX Binary HEX Binary

Low 18 001 1000 19 001 1001

Mid-Supply 29 010 1001 29 010 1001

High 4C 100 1100 4D 100 1100

The OS/A0 pin, after power-up, defaults as an address select input pin (A0). After power-up, the OS/A0 pin can

only be programmed as an OS output when it is in the “High” state. Therefore, 4Ch is the only valid slave

address that can be used when the OS/A0 pin is programmed to function as an OS output. When the OS/A0 pin

is programmed to function as an A0 input the LM95245 will immediately detect the state of this pin to determine

its SMBus slave address. The LM95245 does not latch the state of the A0 pin when it is functioning as an input.

If the OS/A0 pin is not used it must be externally connected through hardware to some state, as shown in the

table, in order to guarantee that the proper address is selected and not in an indeterminate state. The OS/A0

does not have an internal pull-up.

DIGITAL FILTER

In order to suppress erroneous remote temperature readings due to noise, the LM95245 incorporates a digital

filter for the Remote Temperature Channel. The filter is accessed in the Configuration Register 2, bits D2 (FE1)

and D1(FE0). The filter can be set according to the following table.

FE1 FE0 Filter Setting

0 0 Filter Off

0 1 Reserved

1 0 Reserved

1 1 Filter On

Filter Impulse and Step Response Curves depicts the filter output in response to a step input and an impulse

input.

Filter Impulse and Step Response Curves

Figure 8. Seventeen and Fifty Degree Step Figure 9. Impulse Response with Input Transients

Response Less Than 4°C

Product Folder Links: LM95245