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Part Number: AM5728
We're now using AM5728 to desigh a Minimum System and I have several questions about the Power-up Sequencing:
1）According to the datasheet,after powering up the "vddshav8", clock "xi-osC0" should be generated. But now the clock we generated will have an abnormal waveform before it is stable(see the figures below), will this waveform affect the following sequencing?
2.I'm not sure if it is because of the abnormal waveform I mentioned above, I can not get high outputs for the signals of "rtc_porz，porz，rstoutn". What can I do to get the correct outputs?
3.Which signals can be used for judging that the minimum system for AM5728 is operating?
Looking forward to your reply!
This is not a normal oscillator startup. How is the clock generated? What is your power supply solution?
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In reply to Biser Gatchev-XID:
1. "How is the clock generated? "
--I use lmk04806 as the clock generation chip.The figure below is the related circuit diagram:
2.What is your power supply solution?
--I use tps6590377 to power AM5728 up.The files below is the related circuit diagram files:
tpsPower Supply .pdf
tps659037P033_Power Supply .pdf
Is it because of this abnormal signal that affect my system?
In reply to user3925516:
This clock solution is definitely different from the requirements in the AM572x Datasheet SR2.0 Rev. F, section 6.1. If you provide an external clock to AM572x, it must be a 1.8V LVCMOS compatible clock. The xi_osc0 pin is connected to the clock source. The xi_osc0 pin is left unconnected. The vssa_osc0 pin is connected to board ground (VSS).
Thank you for your reply. I will double check the circuit and I still have two more questions:
1. What is the necessary condition to power up the minimum system ?
2. Which signal can be used to determine whether the system is working or not ?
1. All power supplies must ramp-up in the correct sequence and stabilize. Main oscillator clock must be running and stable. Then the PORz reset must be released.
2. There is no such signal. If there is no valid boot source the PMIC will shutdown after 5 seconds.
Thank you so much for your help!
I've got another question.
If there's neither pull-up resistance nor pull-down resistance for number 8,9,10,13 of the configuration pin SYSBOOT[15:0],will that affect the power up of AM5728?
Of course it will. All SYSBOOT pins must be configured with external resistors.
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