TPS68470: PMIC doesn't give configured voltages

Hi Ramesh,

Are the initial voltages of the LDOs correct? If they all start correctly and are inaccurate after being configured please double check the register values.

A large current demand could also push the LDOs toward their current limit, and they may not be able to regulate if the input voltage is too low to accommodate for the dropout.

Best Regards,

Rick S.

Hi Rick,

Default voltage itself is not coming correctly. the default I2C supply which supposed to be 1.8V is 1.4V. We are giving 3.3V as supply. There is no load connected. Even if we write directly to register also it is the same

Regards,

Ramesh

Hi Ramesh,

Is this LDO_S_IO?
You mentioned that this is common to all the LDOs, can you let us know the expected and actual output voltages on the other LDOs to see if there is a common trend?

Thanks,
Rick S.

Hi Rick,

See below for details. We checked three random LDOs/Regulators

Below are the measured values.

 

+V1P8_IO_UCAM ( S_IO_OUT) = 1.4V

+V2P8_AVDD_UCAM ( ANA_OUT) =2.09V.

+V1P2_DVDD_UCAM ( Core out)  – 0.9V

 

Unable to turn on the Core out unless the internal oscillator is enabled instead of the PLL Clock.

 

 

Hi Ramesh,

Is this occurring on more than one board?

If multiple boards are affected, could you verify that each GND is properly connected in the layout?

If this is specific to one board, does re-flowing the IC address the issue?

Thanks,

Rick S.

This is seen on multiple boards. I don't see a clock at the OSC_OUT. When I try to EN_PLL by writing 81 at 0x0D, the EN_PLL is not getting set. I read back 88 at 0x0D which shows that SHORT_LDO ( Pll output is shorted) is set. I measure around 0.27V at the PLL_VDD pin. I checked the impedance at the PLL_VDD and it not short to GND.