LMH0387: Launch Amplitude Register

user4779049

Part Number: LMH0387

Hi Team,

Can you advise me on my questions bellows:

On page 18 of the LMH0387 datasheet stats that, the register address 02h bit 6 through 3 set the Launch Amplitude Fine Control. The default value is 0110 for Nominal Launch Amplitude.

Q1. When the value in bit 6:3 either decrease or increase, the index is signed as plus (+) except 0111 (-2%) case. Are the setting 1001 to 1111 index are -24% to -60 % Instead of +24% to +60%?

Q2. When bit 6:3 is set 0000 (+20%), the device is optimized to handle the input, which Launch Amplitude is 960 mV (800 +20%) (or 480mV: 400+20% if bit7 =1)?

Mita

1 month ago

0 J 1 month ago

TI__Mastermind 21056 points

Hi Mita,

1. The datasheet is correct. The minimal amplitude is -2% of nominal.

2. Yes, your understanding is correct.

Best,
J

0 user4779049 1 month ago in reply to J

Expert 2375 points

J-san,

You answerd that the datashet is correct.

However, it is strage to me.

Either increas or decreas the index from the default value, the Launch amplitudes are signed +.

I suspect that as the index is increas for the nominal, Launch amplitudes are decreasd (signed -).

Can you check it again.

Mita

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Launch amplitude optimization fine tuning for equalizer input.

0000: +20% from nominal.

0001: +16% from nominal. 0

010: +12% from nominal.

0011: +9% from nominal.

0100: +6% from nominal.

0101: +3% from nominal.

0110: Nominal

0111: -2% from nominal.

1001: +24% from nominal.

1010: +29% from nominal.

1011: +34% from nominal.

1100: +40% from nominal.

1101: +46% from nominal.

1110: +53% from nominal.

1111: +60% from nominal.

+1 J 1 month ago in reply to user4779049

TI__Mastermind 21056 points

Hi,

The datasheet is correct. The reason can be found in this e2e post:

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/265953/lmh0387-launch-amplitude-fine-control-resister-02h-6-3?tisearch=e2e-sitesearch&keymatch=Lmh0387#

Best,

0 user4779049 1 month ago in reply to J

Expert 2375 points

J-san,

Thank you for the asnwers.

Mita

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LMH0387: Launch Amplitude Register