BQ25173: Supercap charging issue

Hello

Schematic is Okay do not see any problems.

But charge time on this design will be long, due to power dissipation on the IC.  It could be in thermal regulation with reduced output current, check ISET pin if it is below 1V unit is in thermal regulation.  

Hello Johns,

Thank you for your help.

The customer confirmed that charging occurred after reapplying the RC values ​​applied to the circuit diagram.

However, They expected it to charge at about 760mA with ISET 390 ohm, but it is charging at about 390mA.

Is there a way to increase the charging current?

Hi JH

JH Shin said:

They expected it to charge at about 760mA with ISET 390 ohm, but it is charging at about 390mA.

This could be due to the thermal regulation, power dissipation on the device is too high and output current is reduced to control thermal rise.   An indication this is happening is the ILIM voltage is below 1V.  

Thank you for your response.
I have designed using a 2-layer PCB. How can I reduce heat buildup?

The artwork is as shown in the picture, and the central pad is connected to the bottom layer and GND using two via holes.

Hi Sukwoon

Couple of recommendations to improve thermal:

1.) Top side ground plane will be better.  Looks like all the ground is on bottom plane. More the better.

2.) Increase number of vias under the device.  If you add top side ground add vias near the device to connect top and bottom.

Thank you for your reply.
May I ask an additional question?
Currently, I am using only one supercapacitor. Would there be any issues if I add one more in parallel for charging?
What potential problems could arise?

Hi Sukwoon

Will be no problem adding 2ed capacitor in parallel, this is common.