LMK03328 - Unused Reference Input

Hiroshi Katsunaga

Mastermind 6480 points

Other Parts Discussed in Thread: LMK03328

Hello,

My customer have a question about LMK03328.

[Q]

Please tell me the configurations of unused reference input. Floating ? or terminate to ground ?
Also do you have the recommended register setting for unused reference input ?

Best Regards,

Hiroshi Katsunaga

over 9 years ago

0 Arvind Sridhar over 9 years ago

TI__Mastermind 24205 points

Hi Hiroshi-San,

Please look at Table 2 on Page 36/37 of the datasheet: http://www.ti.com/lit/ds/symlink/lmk03328.pdf

Regards

Arvind Sridhar

0 Hiroshi Katsunaga over 9 years ago in reply to Arvind Sridhar

Mastermind 6480 points

Hi Arvind-san,

Thank you for your fast response.

I looked it before your comment.

My understanding as follows.

Figure 45 is described the equivalent circuit of differential input buffer termination option on PRI/SEC reference inputs.
Table 2 is described the matrix of several mode.
PRI/SEC reference input of LMK033x8 can leave floating because it has internal terminator and ac coupling capacitors.
The input does not have any problem in floating if they do the following register setting in the case of unused input. (It is just example, I think other configurations are possible.)

Is my understanding correct ?

Best Regards,

Hiroshi Katsunaga

0 Alan O over 9 years ago in reply to Hiroshi Katsunaga

TI__Mastermind 32575 points

It is possible to disable the Primary / Secondary input buffer by setting PRIBUFSEL / SECBUFSEL = 11b. This will also save about 10 mA current (per buffer).

Alan

0 Hiroshi Katsunaga over 9 years ago in reply to Alan O

Mastermind 6480 points

Hi Alan,

Thank you for your fast response.
I understood your comment.

Best Regards,
Hiroshi Katsunaga

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LMK03328 - Unused Reference Input