BQ25820: Optimized duty cycle

Shachar Armon

Prodigy 230 points

Part Number: BQ25820

Tool/software:

Hi,

I would like to verify/ confirm the DCDC duty cycle

Our case:

- Lithium ion battery pack, 5S or 6S *the PCBA will be modified between this two battery pack options, required minimal BOM change, meaning FB resistors only

- Charging levels- 30W up to 70W

- External VDC input power- 36Vdc (required for others requirements)

The calculated DCDC charger D.C is 50% to the 5S option and 60% for the 6S option,

what is yours opinion?

Shachar

2 months ago

0 Christian Moyer 2 months ago

TI__Mastermind 33731 points

Hello Shachar,

Based on my calculation the max dutycycle for 5s should be 60% and 70% for 6s. What is the purpose for this calculation? If it is for selecting inductor/MOSFETs, I would recommend using 50% in your calculation, this is when you will see the most noise.

Best Regards,

Christian.

0 Shachar Armon 2 months ago in reply to Christian Moyer

Prodigy 230 points

Hi Christian,

I can control by the design the external VDC input level, meaning to control the DCDC duty cycle by this, I wondering for what duty cycle to design for having the best EMC results and efficiency results with the BQ25820 for charging 5S or 6S with charging current up to 4A

Shachar

0 Christian Moyer 2 months ago in reply to Shachar Armon

TI__Mastermind 33731 points

Hello Sharchar,

Shachar Armon said:
I can control by the design the external VDC input level, meaning to control the DCDC duty cycle by this, I wondering for what duty cycle to design for having the best EMC results and efficiency results with the BQ25820 for charging 5S or 6S with charging current up to 4A

I understand now. I would recommend 60-80% duty cycle.

Best Regards,

Christian.

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BQ25820: Optimized duty cycle