BQ25898D: What is the ISW mean?

Hailiang Zhang

Expert 6785 points

Part Number: BQ25898D

Hi Team,

I am wondering what is the specific definition of ISW? Is it the peak current of Q2, Q3?

Regards,

Hailiang

over 2 years ago

0 Ning T over 2 years ago

TI__Guru 52211 points

Hailiang,

ISW is not on the datasheet. You may refer to ISYS Output current (SW) on page 8 of the d/s.

Thanks,

Ning.

0 Hailiang Zhang over 2 years ago in reply to Ning T

TI__Expert 6785 points

Ning,

Yes. It is ISYS. I see it often named ISW in other D/S. But I'm not sure what exactly it is. Please comment.

Thanks.

Hailiang

0 Garrett Kreger over 2 years ago in reply to Hailiang Zhang

TI__Mastermind 26110 points

Hi Hailiang,

As Ning mentioned ISYS is the output current. The ISYS spec in the datasheet refers to the maximum current the buck converter (made up of Q2, Q3, and external inductor) can output to the system load and battery.

The current observed at SW pin (ISW) is the inductor current.

Best Regards,

Garrett

0 Hailiang Zhang over 2 years ago in reply to Garrett Kreger

TI__Expert 6785 points

Hi Garrett,

Thanks.

I'm a bit confused about the description "SYS Output current (SW)" in section 8.3 on the datasheet. But I understand that ISYS refers to the output capability of BUCK. Right？

Hailiang

0 Garrett Kreger over 2 years ago in reply to Hailiang Zhang

TI__Mastermind 26110 points

Hi Hailiang,

You can think of ISYS and ISW as both referring to the output current capability of the buck converter.

Hailiang Zhang said:
I'm a bit confused about the description "SYS Output current (SW)"

I agree this line is a bit misleading, it says (SW) because the 4A max refers to the current draw at both SYS pin + BAT pin during charging.

Best Regards,

Garrett

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BQ25898D: What is the ISW mean?