TPS61022: TPS61022RWUR

Hi Nathan Ding

Thanks for your reply.

The shortage is at SYS pin of charger IC that is also connected with the input of 5V buck/boost converter.

The output of buck/boost converter shows 450 ohm resistor.

I have two boards and both shows same thing. It means we did something similar to same boards.

One thing i want to add that due to wrong footprint of inductor for buzzer circuit. We added it through some wires.

Do you think it might cause problem?

Thanks 

Hi Ali,

Thanks for update.

What about the impedance of SW pin to ground and FB pin to ground?

Adding the inductor with a wire may not have big impact on this, but you can also try with a correct footprint.

And more, I think maybe you can try to disconnect TLV60146 and TPS61022, and add an external 5V source to TLV61046 to check if it can work normally and if there is any overcurrent condition.

Regards,

Nathan

Hi Nathan Ding

I first removed charger IC, shortage was still there, then removed fuel guage still there. Then i removed 5V buckboost IC, shortage went away.

In one board, if i apply the 5V to the rest of circuitry that requires 5V.it work but one board, those parts are also not working. 

I want to know what possible can cause this.

I was using PD adapter to power the board through USB C.

USB C is connected in CC configuration mode using resistance so it is not supposed to demand higher voltage from pd adapter. It is supposed to work at 5V. Also, i checked charging IC has over voltage protection so it shouldn't be problem.

Thanks 

Hi Nathan,

yes, please check the abs max ratings - as you can see from the datasheet of the TLV61046A the negative voltage is limited to -0.3V on VOUT

Best regards,

 Stefan

Hi Stefan Schauer

I am not sure, i quite understand your answer.

I am looking for possible reason to cause this damage so i can avoid it next version.

As i mentioned before that board was working fine until buzzer circuit inductor was not installed.

As soon, we installed buzzer circuit inductor which is also a buckboost IC.

Both boards get damaged.

How i can avoid this issue again?

Should i add some kind of diode at the output of 5V buckboost circuit?

If yes, can you suggest any part number?

The current for 5V circuitry is no more than 1A.

If you need complete schematic i can send you in private.

Thanks 

Hi Ali,

sorry for the confusion. 

I think you need to debug the TLV61046A part separately - with having the other parts disconnected.

Please check first that the feedback divider is properly set and the connections are there.

Then try to power up ( start with lowest input voltage and a current limit on the supply - also have some load connected to the output,e.g. 10% of max load) the device and check the output voltage - esp. if it ramps up and if it ramps up to more then the output voltage should be.

Best regards, 

 Stefan

Hi Stefan Schauer

The TLV61046A works fine if i applied input to this IC directly.
I am looking for possible reason of the damage of TPS61022. What causes it to short its input in both boards?
Is it possible that L2 generated negative spike and as TPS61022 output directly connected with the input of TLV61046A?

Can you help me to add a negative spike suppression diode for the output of TPS61022 if that is the case?

I ordered new IC that has been damaged to replace on board but I don't want to damage them again.
Thanks

Hi Ali,

negative voltage out of this range will cause damage to internal FET.

Generally we have anti-parallel diode in each pin (for ESD protection), you can test the voltage drop between GND and each pin to find if this diode is damaged. If the voltage drop is about ~0.6V, it is normal, otherwise the diode is damaged.

Also, you can try to measure SW-GND resistance and SW-VOUT resistance of damaged device, so that we can find out if low-side FET or high-side FET is damaged.

Regards,

Nathan