LM89

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SNIS128D – AUGUST 2002 – REVISED JUNE 2014

SMBus start condition at any point during the communication. After the start the LM89 will expect an SMBus

address byte.

9.3.10 Digital Filter

In order to suppress erroneous remote temperature readings due to noise, the LM89 incorporates a user-

configured digital filter. The filter is accessed in the FILTER and ALERT CONFIGURE REGISTER at BFh. The

filter can be set according to the following table.

D2

D1

Filter

0

0

No Filter

0

1

Level 1

1

0

Level 1

1

1

Level 2

Level 2 sets maximum filtering.

Figure 13 depicts the filter output in response to a step input and an impulse input. Figure 14 depicts the digital

filter in use in a Pentium 4 processor system. Note that the two curves, with filter and without, have been

purposely offset so that both responses can be clearly seen. Inserting the filter does not induce an offset as

shown.

Figure 12. Filter Output Response To A Step Input

Figure 13. Filter Output Response To A Step Input

A) Step Response

B) Impulse Response

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