AM5716: am5716

Francesco Residori

Part Number: AM5716

Hello,

I'm developing a board with Sitara AM5716.

I give to the SItara a 20MHz clock from an external oscillator which has a 3.3V LVCMOS output. The oscillator is connected to the XI_OSC0 pin (AE15) (see picture below) and it is working before the PMIC exits from the reset.

Is there any problem if Sitara has the clock signal before powering up?

Best regards

Francesco

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Hi,

Please read section 6.1.2.2 of the AM571X Datasheet SR2.0 Rev. G. OSC0 input clock MUST be at 1.8V level. You may damage the device with a 3.3V clock.

0 Francesco Residori over 6 years ago in reply to Biser Gatchev-XID

Intellectual 450 points

Hi Biser,

I have put a voltage divider to lower the level but probably it is better to put a buffer with a 1.8V LVCMOS output, isn't it?

In order to have the right power-up sequence, do I use 1.8V coming from PMIC to power-on the buffer or do I have to wait more time before giving the clock to Sitara?

Best regards

Francesco

0 Biser Gatchev-XID over 6 years ago in reply to Francesco Residori

TI__Guru**** 393215 points

A buffer will be better, and you should power it from the VDDA_OSC power rail. This will guarantee that the clock will not come before the oscillator internal circuitry is powered.

0 Francesco Residori over 6 years ago in reply to Biser Gatchev-XID

Intellectual 450 points

Thank you very much!

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AM5716: am5716