LMH1297: Target Impedance and Frequency for PDN Design

Owen306

Part Number: LMH1297

When designing my board using the LMH1297, what target impedance should I be using? Also what is the frequency range I should be targeting to stay under that impedance? Right now I was targeting 100mOhms as my target impedance. This based on a 66% dynamic current, 150mA operating current, 2.5V rail and 0.4% ripple. (0.4% ripple is based off the requirement of 10mVpk-pk supply ripple). Thanks.

over 6 years ago

0 Nasser Mohammadi over 6 years ago

TI__Guru* 93670 points

Hi Owen,
We haven't done this type of impedance analyses for the LMH1297 device or evaluation board. Would providing you with the LMH1297EVM pcb layout help you in this analyses? This board was used to qualify the device per data sheet requirements.
Regards,,nasser

0 Owen306 over 6 years ago in reply to Nasser Mohammadi

Prodigy 70 points

Hey Nasser,

Yeah the LMH1297EVM PCB layout and stackup information could help as I should be able to estimate the plane capacitance provided by the board.

Thanks,
Owen

0 Nasser Mohammadi over 6 years ago in reply to Owen306

TI__Guru* 93670 points

Hi Owen,
I checked and you already have access to this file. Please log in to TI.COM, go to mySecure Software. In LMH1297 folder you should be able to .brd pcb layout file.
Regards,,nasser

0 Owen306 over 6 years ago in reply to Nasser Mohammadi

Prodigy 70 points

Hey Nasser,

Do you happen to have the board in another format? I don't have access to something that can open .brd files. Ideally the export format will be compatible with Mentor tools.

Thanks.

0 Nasser Mohammadi over 6 years ago in reply to Owen306

TI__Guru* 93670 points

Hi Owen,
You can use Cadence Allegro Free viewer to view this file. This is available on Cadence site and we use this regularly. Cadence tool was used for pcb layout design of this board.
Regards,,nasser

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LMH1297: Target Impedance and Frequency for PDN Design