BQ25713: Why isn't ChargeOption0 register's PWM_FREQ field value the <default at POR>?

Yevhen Horbenko

Intellectual 510 points

Part Number: BQ25713
Other Parts Discussed in Thread: TPS65982,

Hello guys. Thanx in advance for your attention.

I'm developing a dock-station device. TPS65982 and BQ25713 are used in the project.

I never adjust (via I2C comminication) BQ25713 ChargeOption0 register's PWM_FREQ field. As described in:

SLUSD83A – JUNE 2018 – REVISED JULY 2018:

PWM_FREQ: Reset state: 1b, that is equal 1b: 800 kHz <default at POR>

But in some cases I see the value is 1200KHz that is proved with an oscilloscope.

The SW mistakes (like bitwise shifting ones have been excluded).

I can't realize why PWM_FREQ field could start set as not <default at POR>. Like a workaround I always init PWM_FREQ as 1b at start.

But the issue is still making me concerned.

What reasons could be?

over 4 years ago

0 Kedar Manishankar over 4 years ago

TI__Mastermind 24075 points

Hi Yehven,

Do you have a waveform of the SW node with your test conditions? You can recreate the waveform shown in figure 53. of the datasheet. Keep in mind at light load the converter operates in PFM mode so the above PWM frequency would not be applicable in that scenario

0 Yevhen Horbenko over 4 years ago in reply to Kedar Manishankar

Intellectual 510 points

Kedar Manishankar thank you for your reply.

In my case I can see PWM 1200 KHz or 800 KHz on oscilloscope waveform but not PFM.

I can see either that the corresponding bit ChargeOption0 : PWM_FREQ can be set as 1200 KHz of a reason that is not clear for me.

I can't realize why it's resetable to not <POR default> state.

0 Kedar Manishankar over 4 years ago in reply to Yevhen Horbenko

TI__Mastermind 24075 points

Hi Yehven,

After POR, can you do a register dump? Please show waveform captures as well.

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BQ25713: Why isn't ChargeOption0 register's PWM_FREQ field value the <default at POR>?