TPS6594-Q1: RSTOUT_L keeps low when all power rails are ok

Hi Max,

You mention pin 25 which would be nRSTOUT for the MCU_PORz signal. Note that this device configuration that you mentioned in your prior thread, TPS6594141B, has two reset signals - one going to MCU_PORz and one going to PORz for the SoC. Per the user's guide as referenced in the earlier thread, www.ti.com/lit/pdf/slvuby7 there are many cases that can cause the RSTOUT pin to be driven low. This pin is usually used to handle if there is some error state in the system. The user's guide that I linked lists the states for the device  in section 6, PFSM setting - it includes a drawing of the state machine and the sequences, including this nRSTOUT signal.

So for debugging, first you need to determine what state the part is going into when this is being pulled low, or what interrupts have occurred. Some things that could help you start with this would be to read out the interrupt registers - there is some description in this FAQ: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1112617/faq-tps6594-q1-lp8764-q1-debugging-pmic-behavior-with-interrupt-interpretation Can you please read out these key interrupt registers and check the finding? 

Regards,

Katie

we use this signal going to MCU_PORz, this holds MCU not bootup, so it cannot read any register in this case, how can it be released before system bootup?

For debugging purpose, can you connect USB2ANY or other device to read the registers from the PMIC? 

Regards,

Katie

I used : MSP-EXP432E401Y

Let me modify the board and read it via MSP432E4 SimpleLink

Hello Max,

Were you able to read the interrupt registers?

Tried many times, there is no way to read registers out from I2C via SimpleLink, it says "hardware connected" , but can not read anything, I think there is something wrong with TI "Scalable PMICs GUI".

Max Chen1 said:

One board was working fine for days when debugging, it turns to "RSTOUT_L", pin 25, always low even all power rails outputs are correct

On the TPS6594141B, the nRSTOUT pin is configured as open drain. Can you confirm there aren't any problems with the pull-up resistor or the voltage it is connected to?

Max Chen1 said:

but can not read anything, I think there is something wrong with TI "Scalable PMICs GUI".

Is VIO_IN present? Is the pull-up voltage for I2C1 lines good? 

yes, nRSTOUT pullup to 1.8V ok, but measured the pin 0.625V all the time, something holds it to 0.625v inside the PMIC.

checked the VIO_IN is 3.3V, I2C1 pullup 2.2K on both SDA and SCL.

Hello Max,

I have reached out via email to try to resolve this issue.

We have 3 pin PCB header for external I2C access,

Q1: Can you recommend tools for access PMICs ?

• HW , part number and where to buy?
• SW, download link?

Q2:  in the TI reference design, there is pre-regulator for 3.3V, then 3.3V to PMIC, why do you still need MoSFET for over voltage protection, should we remove this FET?