LMH6518: Will LMH6518 accept differential input?

diverger

Part Number: LMH6518

In the datasheet, it says:

The input is differential but is driven single-ended as long as the conditions of Table 6 are met, and there is good
matching between the driven and undriven inputs from DC to the highest frequency of interest.

I'm a little confused, is it mean "although the input is differential, but it can ONLY be driven signle-ended" or "although the input is differential, but it can ALSO be driven singled-ended"? I must make sure this, because I'm considering put another full differential amp before it.

Thanks.

over 6 years ago

0 kai klaas69 over 6 years ago

Guru 140200 points

Hi,

your phrase can be found in section 8.2.1.2.2 and is referring to the application shown in section 8.2. But in section 7.3.1 the following is mentioned:

"7.3.1 Input Preamplifier

The LMH6518 has a fully differential preamplifier which has a consistent 150-kΩ impedance across all gain
settings. The LMH6518 is also driven with a single-ended signal source. The preamplifier has two gain settings.
See Input and Output Considerations for details."

Kai

0 Sean Cashin over 6 years ago in reply to kai klaas69

TI__Mastermind 21986 points

A single ended signal is technically differential with respect to ground. So ALSO.

0 kai klaas69 over 6 years ago in reply to Sean Cashin

Guru 140200 points

Hi Sean,

hmm, the original poster is right somehow. The datasheet is indeed confusing in this point because it only discusses the connection of a single ended signal. Even the eval board is only supporting this configuration.

Kai

0 Sean Cashin over 6 years ago in reply to kai klaas69

TI__Mastermind 21986 points

Hi Kai,

You are right as always Kai. There are no examples in the datasheet showing differential input either, and all the specifications are for "single ended input drive". I don't see anything preventing a fully differential input however, other than a lack of examples. Do you have concerns?

Best regards,

Sean

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LMH6518: Will LMH6518 accept differential input?