BQ24074: The PIN CHG oscillate at the end of charge.

Romain PENOT

Part Number: BQ24074
Other Parts Discussed in Thread: BQ27541,

Hi,

I use the BQ24074 for charging a PACK BATTERIE with a Li-ION 3.6V 6500 mAh and a BQ27541.

When the battery is around 80% and higher in charge with USB charger (5V-2A) the pin CHG oscillate with around 1 secondes but is very random.

I have no idea why, someone could help me about this ?

Yours faithfully,

Romain PENOT.

over 6 years ago

0 Raheem over 6 years ago

TI__Mastermind 21590 points

Hello Romain,
This is due to the safety timer expiring. You currently have the charge current set to about 684mA. With a 6500mAh battery, it would take about 9 and half hours to fully charge the battery. The default safety timer you currently have due to the TMR pin floating is 5Hrs so the timer will always go off. Can you try increasing the charge current and the timer duration.

0 Romain PENOT over 6 years ago in reply to Raheem

Prodigy 80 points

Thanks you for your advice, I will try with R ISET at 680 Ohm, R ILIM at 1100 Ohm and R TMR at 62 kOhm.

But the default appear sometime juste after few minute when the batterie is quite full.

So the timeout do no explain that.

0 Raheem over 6 years ago in reply to Romain PENOT

TI__Mastermind 21590 points

Romain,
Does the oscillation appear after the /CHG is high impedance indicating charging done?

0 Romain PENOT over 6 years ago in reply to Raheem

Prodigy 80 points

Sharafadeen,

The oscillation are before the charging is ending and when is full still continue to oscillate after the charge ending.

When I say is oscillate, is logical so 0V to 3.0V (0 to 1) is not analogue variation.
So is CHG pin change state to high impedance to low impedance.

Best regards.
Romain PENOT.

0 Raheem over 6 years ago in reply to Romain PENOT

TI__Mastermind 21590 points

Romain,
Can you post a picture of the /CHG oscillation?

0 Romain PENOT over 6 years ago in reply to Raheem

Prodigy 80 points

Raheem,

My problem is resolved thanks for your help. So they have multiple sources, one is the incorrect value of the resistance and the other comes from my USB cable.

I'm hoping the oscillate no appear again, and if yes I will recontact you.

Yours faithfully,
Romain PENOT.

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BQ24074: The PIN CHG oscillate at the end of charge.