BQ24295 EVM - incorrect current limit

Natallia Holubeva1

Hello e2e,

My customer is testing the EVM and is unable to draw enough current. He is using 1A wallwart.

In previous testing, I found the VBUS falling to near the Input Voltage Limit.

In this case with the thick cable VBUS is not falling. BAT voltage is nowhere near the Charge Voltage Limit. So what is limiting the current?

Thank you

over 9 years ago

0 Ryan May over 9 years ago

TI__Genius 13700 points

Hello Natallia,

Could you post a screen shot of the EVM GUI for the 1.5A Input Current Limit case?

What is the charging current? I ask because once the input current limit was high enough the charging current tapered of and which would allow the charger to operate normally and follow the ICHG current.

0 Natallia Holubeva1 over 9 years ago in reply to Ryan May

TI__Expert 6550 points

Ryan,

Thank you fro replying. The charging current measurements are posted above.Is there a current at a particular pin you are looking for?

Natallia

0 Ryan May over 9 years ago in reply to Natallia Holubeva1

TI__Genius 13700 points

Hello Natallia,

There is a setting for the battery charging current that is set in the registers of the device.

The 5th setting down on the EVM GUI is for the charging current. What is this set for.

0 Natallia Holubeva1 over 9 years ago in reply to Ryan May

TI__Expert 6550 points

Hello Ryan,

In the past I’ve tried changing ICHG and it worked. I saw I could adjust the input power, which indirectly limited the charge current. When I tried to pull more than 700mA, I saw VBUS sag. It’s not sagging much with this new cable, but I can’t get more current.

0 Ryan May over 9 years ago in reply to Natallia Holubeva1

TI__Genius 13700 points

Hello Natallia,

Looking at the register setting everything appears to be in order. So even if you are requesting more current it is maintaining a consistent voltage on the input but holding the charging current at the same value?

Have you tested the adapter itself with a resistive load to ensure that it is even capable of delivering up to 1A?

0 Natallia Holubeva1 over 9 years ago in reply to Ryan May

TI__Expert 6550 points

Ryan,

It does the same thing from a bench supply. It rightly limits the voltage, but it’s as if there is an additional I limit somewhere. Voltage at the input thermals stays at 5V in this test b/c I’m using heavy wire.