TPS51285B: 5V and 3.3V outputs shutdown when soft shutdown in Windows 10.

zhuyt05

Part Number: TPS51285B

Dear Sir, we are now using TPS51285B as BUCK, TPS650945 as PMIC and CPU is Intel APL-I E3940.

When we shutdown the board in Windows 10 OS, the 5V and 3.3V output of TPS51285B are shutdown also.We notice that there is no communication interface between TPS51285B and CPU. How does this work?

Thank you!

over 5 years ago

0 Yuchang Zhang over 5 years ago

TI__Mastermind 18510 points

Hi, Could you please upload the total schematic of 51285 and Did you catch some waveform when the 51285 shutdown, Vin/Vreg3/V5A/V3P3A?

Yuchang

0 zhuyt05 over 5 years ago in reply to Yuchang Zhang

Prodigy 110 points

Dear Sir,

Vin=12V,Vreg3=3.3V,V5A=0V,V3P3A=0V,when the 51285 shutdown.There are 2 options in the schematic and we use option 1（auto power-on）.

2021.UP.pdf

0 Yuchang Zhang over 5 years ago in reply to zhuyt05

TI__Mastermind 18510 points

Have you tried another option? Will check more detailed after Chinese New Year.

0 Peter James Miller over 5 years ago

TI__Guru 56925 points

zhuyt05

Check the voltage on the EN1 pin (Net 51285) The net is labeled in the schematic you shared, so it could contain a connection on another page of the 28 page schematic that was not shown on the 4 pages shared. It is possible that the processor has the ability to pull EN1 low to enter sleep mode. Since EN2 is powered by the output of channel 1, pulling EN1 low will disable both the 5V and 3.3V outputs.

0 Yuchang Zhang over 5 years ago in reply to Peter James Miller

TI__Mastermind 18510 points

zhuyt05

Any update based on Peter and my suggestion?

Power management

Power management forum

TPS51285B: 5V and 3.3V outputs shutdown when soft shutdown in Windows 10.