LMH5401-SP: Space-grade solution for negative rail

charlesw

Part Number: LMH5401-SP
Other Parts Discussed in Thread: LM137JAN-SP, TIDA-01027, ADC12DJ3200QML-SP, ADC12DJ3200, LMH5401, TIDA-01028

Hello,

I'm wondering what your thoughts might be for a space-grade solution for generating a -2.5V rail for the LMH5401-SP. I have some flexibility in the input power. My main three options are 3.3V, 5V, and 12V.

My first thought is to use a space-grade hybrid module with a negative rail followed up with an LM137JAN-SP. The main issue I have with this solution is how large those hybrid modules are and their typical minimum voltage requirement can be higher than 12V.

What I'm now very much considering since we're still in the design/prototype stage, is to use a mixture of commercial and space-grade components. It would be a space-grade data converter, clock generator, and amplifier powered by a commercial reference design (TIDA-01027).

I'd appreciate any thoughts, thank you.

over 5 years ago

0 Michael Steffes over 5 years ago

Guru 48395 points

Hey Charles,

Why do you think you need a negative supply - FDA's do a pretty good job with single supply - the CM loop will level shift even a DC coupled bipolar input up into range above ground normally. No ADC's require a swing to true ground input that I know of.

0 charlesw over 5 years ago in reply to Michael Steffes

Intellectual 800 points

Hi Michael,

My design will be targeting the ADC12DJ3200QML-SP for a DC-coupled input. The datasheet says the ADC has a 0-V VICM and it recommends using the LMH5401-SP with split supplies with an VOCM equal to the midpoint of the two supplies, which would be +/- 2.5V:

0 charlesw over 5 years ago in reply to Michael Steffes

Intellectual 800 points

Michael,

Another thing I'd like to add is I've been referencing TIDA-01028 for help with my own design. It uses the ADC12DJ3200 with the LMH5401 on the frontend with +/- 2.5V rails.

0 Michael Steffes over 5 years ago in reply to charlesw

Guru 48395 points

Well that is interesting, a split supply ADC with ground centerpoint. (I wonder if you could operate it single supply) There has also been quite a lot of single supply reference designs done with the LMH5401 - can't find them on the new product landing page format,

Well yes, driving +/-2.5V ADC will need +/-2.5V on the LMH5401 - watch out for its output CM voltage errors and temp drift - if you have any temp range.

0 Gerold Dhanabalan - High Performance Radar over 5 years ago in reply to Michael Steffes

TI__Genius 14455 points

Hi Charles,

To understand your requirements better, your Vin could be 3.3V, 5V or 12V. Vout = -2.5V.

What is the Iout?

Do you want space grade components or commercial is ok?

Do you prefer power modules (integrated inductor) or prefer converters (integrated FETs with external inductors)?

Do you have any ripple requirements?

Any other requirements that we need to be aware.

Regards,

Gerold

0 Michael Steffes over 5 years ago in reply to charlesw

Guru 48395 points

So Charles, I had not seen that TIDA but mentioned earlier I could not find the older single supply reference designs (of which there are many)

You might not be interested, but I did find them now in the recently reformatted product pages - one issue, is those new pages populate really slowly - so if you think something is not there, just wait awhile. Anyway, once it populates , click on design and development where you know get another level to click for reference designs.