TE0820 + TE0706 First Power-Up Problems

[nbayhan]

Hi,

I have a TE0820-04-4DE21FA board and want to evaluate it with a TE0706-03 carrier. I have a problem regarding powering-up the two boards. Please note that both are newly bought and I could not be able to make them work yet. I am using a power supply with 5V - ~3A limits to supply the system.

Case 1: Powering up TE0706-03 carrier only. Switches and jumpers are in default positions. I can see 5V->3.3V conversion is working from J5 & J6. Board seems fine, sinking ~60mA average current.

Case 2: Putting TE0820 on top and powering up two boards together. This is where it fails. The 3.3V to the TE0820 (VIN in schematics) becomes unstable and switching very rapidly between on and off. Together they sink ~25mA average current. So I cannot do anything since the board power-up is not completed properly.

My guess is (please see the attachment): when VIN is available, PG_1.8V rises properly. This enables the "3.3VIN to 3.3V" switch, and somehow this creates a drop on VIN and PG_1.8V falls again. Then VIN becomes re-available and this oscillation continues forever. I can also see this oscillation on TE0820 D1 (DONE LED) as rapid blinking.

I have done power to ground short checks on TE0706 J5 & J6 when two boards are together, with and without VCCIO & SD jumpers (on 1.8V). Everything seems OK.

So, any suggestions on this? Any help would really be appreciated.

Best regards,
Nusret

[JH]

Hi,
TE0706 has a under voltage protection(4.06V). Maybe voltage is shortly under the limit and this force the board to reboot. How long is your power cable? Which kind of power supply did you use? Do you have another power supply?

br
John

[nbayhan]

Hi John,

I am using a lab-style adjustable DC power supply and the cables are standard crocodiles (around 20ish cm) with a barrel jack adapter addition. I have also tried slightly under-above voltages (like 4.5 - 5.5) and all I can see is the change in abovementioned oscillation frequency.

I do not have any other supply right now but I am planning to grab a wall plug adapter to try it out.

Thanks,
Nusret

[bastionbooger]

anything different if you hold the reset button during startup? I mean, is the 3.3V stable in that case while reset is asserted?

Is the 1.8VOUT stable?

what instrument are you using to measure the fast change in voltage?

[JH]

Hi nbayhan,

can you set current on your lab-style adjustable DC power supply? If yes, please check if it's set to the maximum range(3A).

Can you measure the voltage on the  power jack (J1) of the TE0706 on power up?

br
John

[nbayhan]

Hi,

I have just tried with a wall plug adapter with 5V-2A ratings and now it works!!

I am not sure what happens with the power supply but I guess it strictly limits the start-up current overshoots at 3A. I do not think the wall plug adapter has such limiting capability and it can bring the board up.

Thank you very much for your time and help.

Best regards,
Nusret