SK-AM62A-LP: AM62A Low-Power SK EVM power off

Zehui Li

Part Number: SK-AM62A-LP

AM62A Low-Power SK EVM User’s Guide points out two ways to power off. I wonder whether the power down sequence of AM62A can be followed when such sudden power loss occurs. It seems the TPS6593 will immediately shut down.

over 2 years ago

0 Senthilkumar Srinivasan over 2 years ago

TI__Mastermind 43660 points

Hello Zehui,

Which version of the EVM are you using?

We have an implementation on E2 version in such a way that the PMIC will process controlled power down when any of the power off procedure is followed.

Regards,
Senthil

0 Zehui Li over 2 years ago in reply to Senthilkumar Srinivasan

Intellectual 540 points

Senthil,

We are using E1 version. How did you design this part in E2 version? Maybe we can refer to that.

0 Senthilkumar Srinivasan over 2 years ago in reply to Zehui Li

TI__Mastermind 43660 points

Zehui Li,

We did this change on the E2 version - Routing LDO_3V3 (Type C PD controller LDO output) to Pin No 49 (FB_B3) of the PMIC instead of SoC_DVDD3V3. In this way, we got 8.3ms between LDO_3V3 and VCC_3V3_MAIN ramp down which can be utilized by the PMIC to initiate controlled power down sequence.

In E1 version, SoC_DVDD3V3 voltage drops below UVLO too fast (in microseconds) not allowing the PMIC to execute a power down sequence before the power is lost.

Regards,
Senthil

0 Zehui Li over 2 years ago in reply to Senthilkumar Srinivasan

Intellectual 540 points

Senthil

According to your reply, I try to figure out what happpened in this situation. Please let me know if I'm wrong.

VCCA input undervoltage monitoring event triggers the power down sequence according according to VCCA_GRP_SEL and x_RAIL_TRIG bits which I think select Orderly shutdown.
You set BUCK3_GRP_SEL to choose a group for BUCK3, and set FSM_TRIG_SEL of this group to Immediate shutdown. When SoC_DVDD3V3 drops, the BUCK regulator undervoltage event occurs, thus, Immediate shutdown is triggered so that power down sequence is violated.

0 Xu(SH) Liu over 2 years ago in reply to Zehui Li

TI__Expert 3745 points

any conclusion here, shall we close this issue now?

0 Zehui Li over 2 years ago in reply to Xu(SH) Liu

Intellectual 540 points

Hi Xu，

I'd prefer not to.Still waiting for the reply.

+1 Biao Li over 2 years ago in reply to Zehui Li

TI__Expert 6420 points

Hi Zehui,

Yes, as below, FB_B3 can be set as a free resource of Vmon, and this is same as other BUCK OVUV trig(buck error), but it will not cause a immediate shutdown. pls refer to below NVM setting, any furth questions about PMIC 6593 you need open another thread, we will assign another expert to support. thanks a lot.

BR,

Biao

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SK-AM62A-LP: AM62A Low-Power SK EVM power off