TPS65910: Startup waveform overshoot

James Zhan

Expert 4365 points

Part Number: TPS65910
Other Parts Discussed in Thread: AM3354, AM5728

Hi team,

My customer is using TPS65910 as the PMIC of the AM3354. But they have some questions about the startup waveform.

As you could see below waveform, VPLL have the Startup overshoot, same as VDAC, VMMC, VAUX2.

Besides, for the VDD-CORE, it has weird ladder waveform as below.

Could you please help to provide some advice for this? Thanks.

over 6 years ago

0 Nick Jakse49 over 6 years ago

TI__Expert 4155 points

James,

Your question has been assigned to our device expert. He should get back to you soon.

0 James Zhan over 6 years ago in reply to Nick Jakse49

TI__Expert 4365 points

Hi Nick,

Do you have any updates for this?

Thanks.

0 Brian Berner over 6 years ago in reply to James Zhan

TI__Mastermind 30280 points

James,

I need to re-assign your question to the Sitara processors team. I am the apps engineer for the TPS65910, but I do not know of any documentation that says the TPS65910 can be used to power the AM5728.

0 Biser Gatchev-XID over 6 years ago in reply to Brian Berner

TI__Guru**** 393215 points

James,

TPS65910 cannot be used with AM5728. Please verify PMIC and processor part numbers.

0 James Zhan over 6 years ago in reply to Biser Gatchev-XID

TI__Expert 4365 points

Hi Biser,

Sorry that I've made typo, which should be Am3354.

Could you please help to check the startup waveform?

Thanks.

0 James Zhan over 6 years ago in reply to Biser Gatchev-XID

TI__Expert 4365 points

Hi Biser,

There is one more questions about the VDD-CORE waveform. As you can see the below picture, the VDD-CORE has a step down voltage while the system is running. Does this has something to do with the Linux core frequency?

By the way, while testing the pin of the TPS65910: SCL_SDA_SDI, the waveform has the 400mV dropout? Could you please help to provide some advices?

Thanks.

0 Ahmad_Rashed over 6 years ago in reply to James Zhan

TI__Genius 13567 points

Hi James,
The power management on this chip can change voltages on VDD_MPU and VDD_CORE based on run-time conditions. No need to worry about those voltage changes. Regarding the overshoot are the voltages stable by the time PORz is released?

0 James Zhan over 6 years ago in reply to Ahmad_Rashed

TI__Expert 4365 points

Hi Ahmad,

Do you mean these step down waveform is okay? Could you please help to provide more details about the changing voltage on VDD_CORE?

By the way, while testing the pin of the TPS65910: SCL_SDA_SDI, the waveform has the 400mV dropout? Could you please help to provide some advices? There is 4.7kohm pull up resistor to VAUX2.

Waveform as below: