LP-AM263: Clarification on Power consumption

Hi Yashasvini,

Can you provide some details on your specific setup:

• What did you to do disable the ethernet phys?
• How and where are you measuring the current for 5V into J11 or J5?
• What is the AM263 doing during current measurement?

I agree that >200mA delta is more than I would expect for the Test Automation, but I am also looking into what we should be expecting here.

Thanks,
Mike

As a follow up question, are you sure all the other rails are being powered and the AM2634 is being released from reset?  Can you measure the voltage of the1.2V, 3.3V and 5V rails (VDD_AM263_1V2, VSYS_3V3, VSYS_5V0 respectively)?  Can you also see what the voltage level is of AM263_PORZ.

We've seen in the past when trying to power the LaunchPad from one of the 5V headers, the board could not pull enough power, causing the voltage rails to droop, and the PORz was never released high.  I want to see if something similar is happening here.

Thanks,
Mike

Hi Mike,

Thanks for the quick response. Please find below the answers for your queries:

a) We have disabled DC regulators (U30 and U31) which generates 2.5V and 1.1V supply to Ethernet PHY by connecting R149 and R157 to GND
b) We had connected external Power supply (5V) to J5 and monitored the current in Power supply
In order to provide 5V through J5, we had cut the USB cable and had provided 5V through external Power supply and had monitored current
c) AM263 LP was powered on as we received from TI. No Firmware was loaded.

We will measure the voltage levels at 1.2V, 3.3V and 5V rails and at AM263_PORZ and will update soon.

Regards,
Yashasvini

Hi Mike,

We measured the voltages as mentioned below:

1. With 5V through USB port

VDD_AM263_1V2 = 1.2V, VSYS_3V3=3.3V, VSYS_5V0=5V, AM263_PORZ=3.3V

2. With 5V through J11

VDD_AM263_1V2 = 1.2V, VSYS_3V3=3.3V, VSYS_5V0=5V, AM263_PORZ=0V

As guessed by you, board is in reset condition in Test case-2. As per our requirement, we need to provide input voltage through Boosterpack header. Kindly suggest solution.

Regards,

Yashasvini K

Hi Yashasvini,

The AM263_PORZ line is generated by logically ANDing together 3 signals (this is component U2 in the schematic):

• AM263_PORz_PB
• PG_VDD_1V2
• PG_VSYS_3V3

Can you measure the voltage of these 3 signals and see which one is holding AM263_PORz low?

Thanks,
Mike

Hi Yashasvini,

Also, there is this E2E post that you might find useful.

e2e.ti.com/.../lp-am263-launchpad-power-source-from-boosterpack

Thanks,
Mike

Hi Mike,

We measured all three input signals and observed that AM263_PORz_PB is always low. 

We further debugged and saw that the above signal is driven by "TA_PORZ" which has pull up to VSYS_TA_3V3. 

U36 is generating VSYS_TA_3V3 output with VUSB_5V0 as input.

Since we are powering the LP through Boosterpack header, VSYS_TA_3V3 is always '0'. Hence the board is in 'RESET' condition. When powered through USB, board is in working condition.

We pulled up "TA_PORZ" to VSYS_3V3 and observed that LP is drawing same current in both conditions i.e., when powered ON through USB and Boosterpack.

Regards,

Yashasvini K

Hello Yashasvini,

Thanks for sharing these additional observations. It looks like the issue can be attributed to what Randy previously observed (via Mike's shared E2E post) regarding the VSYS_TA_3V3 rail having trouble with the 5V input from the BoosterPack. I think at this point there is enough information here to say that your observations align with what we have previously assessed as a shortcoming with the EVM design when powering it from the 5V rail.

That said I would like to confirm what the exact measured voltage is for VSYS_TA_3V3 in your board when powered via the BoosterPack header? It sounds like there may be variance between EVMs or perhaps with how power supplies are sourcing the pins as for Randy, he was able to get enough voltage to get the device to come out of reset and operate.

Best Regards,

Ralph Jacobi