I have a very strange problem with powering up BeagleBone Black (rev C)… When i try to power it up from some cheap AC adapter it works fine, but when I connect to to my labolatory power supply the power LED on board is lid for a second and then doesnt power up the MCU and turns off intead. I have connected both supplys to osciloscope and they are both stable, the laboratory one even more. Why is the power controller on the BeagleBone Black refusing to power up the MCU when powered from lab supply? I have no idea what is this about. I would aprichiate any help.
Have you tried leaving the power supply on and plug in the cable to the board or are you using the power switch on the power supply?
I just plug the power and the board normally should turn on but it doesnt. I then press the pwr btn but the result is the same as if i plugged the power supply in.
I read you post again:
I am plugging a cable that has power already, not using the switch.
As Gerald has said before, check the ramp up of the power supply.
Some of the lab supplys have slow ramp ups.
Yes they are very stable and VERY good regulation but
the BBB design requires a fast ramp up supply.
What is the exact circuit that requires a fast ramp?
The power management IC, TPS65217C.
Is there a workaround for this? I thought that pre charged capacitors could help but in my application power to the BeagleBone Black is aplied in the same time as to the rest of the circuit.
We are working on one if we can collect enough information to confirm the issue. it appears to be a power supply issue that creates a condition that the TPS65217C does not like. If you use a good power supply, the issue is not there.
I dont agree here, and this is the weird part. A cheap 5V wall plug adapter works great and a certified meanwell supply does not. Can it be a case related to linear/ switching power supply?
Not likely. As I said we need more boards that fail and the power supply that is used with them. What I have seen is that it tries to switch to the battery, that is not there, for whatever reason. Theory is it sees a voltage drop due to the inrush limit on certain power supplies. I have fixed this on a few boards by connecting the TS signal hard to ground using the battery pins on the board.
What I see when the board “does not power up” is the PMIC cycling on and off. You can look at the 5V output rail of the PMIC for this condition.
I understand, thank you for the info. I will make more attempts at monday with another bbb board. For now I have a 10k resistor on the TS pin because I intend to use the battery to. If the voltage is measured on the resistor ill swap it to lower value one. I hope ill get it working using meanwell power supply.
Another test here would be to connect the battery and see if after it switches to the battery if it switches back to the DC input.
How can I know either it switched without taking the battery out?
The output voltage level is different. When the DC is contented it is supposed to go to the DC input and go into charge mode for the battery. Measure the output voltage of the PMIC. If it is 5V, then it is DC in. If it is 3.7V +/- then it is running on the battery.
Ill get it tested, thank you. If this worked it would solve my problem.
A question regarding battery though- if i leave the bbb under battery supply, but turn off the mcu with pwr button, what will be the current drawn by TPS chip? Wont it dry the battery through the night? Lets say its a single li-ion cell 2200mAh
I have a similar problem, using a “B&K Precision 1550” Lab Bench Power Supply.
When you turn on the Output of the supply, the BBB Power Light blinks once and
the BeagleBone Black does not boot.
If you put an oscilloscope on the output of the supply and watch it turn on, then
the power supply overshoots up to 6 Volts, before returning to the 5 Volt setting.
It turns out that the Power Management IC used in the Beaglebone Black will
do an over-voltage shutdown at 6 Volts for protection. So, that is why it does
one-blink then shuts-off.
So, not only do you need a certain rise time, which the B&K power supply
meets, but you can not have any large overshoot. No good power supply
should have this much overshoot, but the B&K does, so it has problems
running a BBB.
It could also be that he has current limit set too low. Set the current limit to 2A or more. It would be helpful if we could see an oscilloscope capture of the startup waveform.