TPS65381 & TL7700

Hi Charles,

I had seen that post before, but unfortunately I'm not clear enough.
As a basic test of TPS65381 IC, I want to setup this with micro and without using TL7700.
So at first I connected 5V to VBATP and IGN directly to VBATP and for the second try, I connect 3.3V to IGN pin. But in both cases WAKE_UP event didn’t happen (circuit diagram is on page 91 of TPS65381 datasheet). I saw zero voltage on regulators output (for example: VDD1_G or VDD5 were both zero).
Isn’t true that TPS must be wake up and go to the reset state while I connect supply to IGN meanwhile TPS is in standby state?

Thanks,

Fatemeh

Hi Charles
At first I should thank you for your help.
As you mentioned 5V is not enough for power up, so by modifying VBATP to 12V, my problem was solved.
If I can ask another question in this thread, I need your opinion on the other problem that I have encounter recently.
All regulators are ramped-up to their respective voltages and the MCU is received 1.5V from the VDD1 Regulator. The NRES pin is pulled up which is 3.3V on the MCU side. The device is in diagnostic state now and the MCU is always resetting.
My problem is I cannot connect to the target by my code in CCS. The error message is: “Unable to access device register”.
Do you have any idea about causing this error?

Thank you very much,

Fatemeh

Hi Fatemeh,
Did you say 1.5V is supplied to the MCU? I wonder if the 1.5V on the core supply trips the internal voltage monitor in the MCU for out of regulation. The core supply to the MCU should be 1.2V . When the internal voltage monitor detects out of regulation it will pull reset.

Hi Charles,
The processor we are using is “TMS570LS20216” that uses 1.5V as a Core Supply Voltage (VCC).
What I recently understand that the VCC and VCCIO voltages are fluctuating so this is surely made the Voltage Monitor to reset the micro. Monitoring these two voltages, I saw that they dropped for more than few microseconds also VDD1_G and VDD3/5 (pin 26 and 21 of the TPS65381 IC) have the same situation.
Now I am trying to find out the reason of voltage fluctuation on these pins.

Thanks for all of your help,
Fatemeh

Fatemeh,

If you have an issue with the power management chip there are some other forums that specialize in power management.
You should post there for problems in the power supply circuit:

e2e.ti.com/.../26
e2e.ti.com/.../200 for the TPS65381

e2e.ti.com/.../886 TL7700

Anthony,

For now, my problem has been solved. There was just a problem with the power supply connections to the circuit.

Thank you for these pieces of information. If I have any question about the power management chip, I'll start a new thread in that forums.

Regards,

Fatemeh

Super glad to hear that.