BQ25606: charge current has oscillation

Roy Chou1

Part Number: BQ25606

Hi Team,

We are using BQ25606 now and we are finding if the VBUS is 4.5V-4.6V, the charge current through the battery will have oscillation. If we boost the VBUS to 4.7V, the issue will disappear. (VBAT = 4V，Icharge = 1.8A)

(Measurement is showing as below. Green line is Icharge. Top is long scale and bottom is enlarge.)

Schematic is showing as below.

Do you have idea for this issue?

Roy

over 4 years ago

0 Ning T over 4 years ago

TI__Guru 57341 points

Roy,

Please visit https://e2e.ti.com/support/power-management/f/196/t/890626 for BQ25606: Schematic Review and PCB Layout Design Tips. Additional Information including FAQs is available http://www.ti.com/lit/an/slva924/slva924.pdf Designing A Standalone Single Cell 3-A Charger with the bq25606.

Please also check if the input source is over-loaded, either the current exceeds the input current limit or the VBUS pin voltage falls below the input voltage limit.

When the input current limit or input voltage limit is reached, the device then reduces the charge current until the input current falls below the input current limit and the input voltage rises above the input voltage limit. Please refer to Extract maximum power from the supply when charging a battery (http://www.ti.com/lit/an/slyt569/slyt569.pdf) and 9.3.6.2 Dynamic Power Management on https://www.ti.com/lit/ds/symlink/bq25616.pdf for the details.

Thanks,

Ning.

0 Roy Chou1 over 4 years ago in reply to Ning T

TI__Genius 16055 points

Hi Ning,

please refer below results. All the voltage are measured near BQ25606.

The “peak” and “low” refers to the points of ringing current, i.e. curser “a” for peak, curser “b” for low.

The result shows the Vbus must be higher than Vbatt+0.2V, otherwise the current will be decreased until the voltage is higher than Vbatt+0.4V

Please confirm if the hysteresis threshold is as what we designed. Thanks.

Roy

0 Ning T over 4 years ago in reply to Roy Chou1

TI__Guru 57341 points

Roy,

Yes. Please 8.3.2.4 Input Voltage Limit Threshold Setting (VINDPM Threshold) on the d/s.

Thanks,

Ning.

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BQ25606: charge current has oscillation