LM3880: LM3880 for power sequencing of Zynq Ultrascale

Elizabeth Abraham

Part Number: LM3880
Other Parts Discussed in Thread: TIDA-01480, , TPS568215, TPS56C215

I am designing a custom board using Zynq Ultrascale and I am using TIDA-01480 power supply design. I am planning to use LM3880 for power sequencing.

I am confused with EN pin of LM3880. In TIDA-01480, the first priority buck converter is TPS568215 and TPS56C215. i have the following questions:

1) Can I give the VIN(5V) to the enable pin of the above buck converters?

2)If so, Is it OK to give the PGOOD signal from any of these buck converters to the enable pin of LM3880? Please find the attachment.

3) If this method is not possible, how can I implement power sequencing using TIDA-01480 and LM3880 for Zynq Ultrascale.

Thank you in advance

over 1 year ago

0 Elizabeth Abraham over 1 year ago

Prodigy 30 points

0 yihe over 1 year ago in reply to Elizabeth Abraham

TI__Guru 66240 points

1. As data sheet clearly state, it is not recommended to use VCC to drive the EN signal since this violates the spec

2. You use POWER_GOOD to drive the EN. but please ensure that POWER_GOOD shall reach EN on threshold until the VCC is above 2.7V

Regards

Yihe

0 Elizabeth Abraham over 1 year ago in reply to yihe

Prodigy 30 points

Thank you for your prompt response. In question 1, I am not asking about LM3880, but it is about buck converters used in TIDA-01480. Can I enable the buck converters TPS568215 and TPS56C215 which has priority 1 a and 1 b using VIN (5V)? Please find attachment for TIDA-01480 block diagram.

After this buck converter are on, I am planning to give its PGOOD signal to enable the sequencer LM3880. Is this method possible or not? Please advise me on this.

Thanks in advance.

0 yihe over 1 year ago in reply to Elizabeth Abraham

TI__Guru 66240 points

As for TPS568215 and TPS56C215, we are not familiar this part. I will move this post to the right team.

LM3880 is good.

Regards

Yihe

0 Amod Vaze over 1 year ago in reply to Elizabeth Abraham

TI__Mastermind 26820 points

Hi Elizabeth,

Yes just looking at the TPS568215 and TPS56C215, connecting a 5V Vin to EN pins of these converters would enable these ICs and the PG output can be used to drive the EN of the sequencer. The current implementation of TIDA-01480 has a set of RC delays driven by VIO (see page 6 of schematic) to generate the EN signals for these two buck converters. So, please be sure to check out the sequencing requirements and if the scheme you are planning works for your needs.

I found something about the sequencing in the TIDA-01480 here: https://e2e.ti.com/support/tools/simulation-hardware-system-design-tools-group/sim-hw-system-design/f/simulation-hardware-system-design-tools-forum/720787/tida-01480-power-supply-sequencing-in-tida-01480 which may be helpful. It does refer to the LM388x for sequencing and generating these EN signals which is what it looks like you plan to do.

Hope this helps.

Thanks,
Amod

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LM3880: LM3880 for power sequencing of Zynq Ultrascale