BQ25173: BQ25173 in combination with IRM-01-3.3

LeddeL

Part Number: BQ25173

Hi,

For a design we would like to use the BQ25173 in combination with the IRM-01-3.3 to charge a 3V supercap to 2.7V.

The meanwell power supply has a voltage rating of 3.3 volts with a +/- of 2.5%. This means the power supply would have a minimum low of 3.217V.

The BQ25173 has a VIN_LOWV of maximum 3.15V. That should be enough. But the IRM-01-3.3 also has a maximum ripple and noise rating of 150mVpp. If we take this noise in account we could get under the minimum of 3.15V of the BQ25173.

Could this noise be any problem for the BQ25173?

over 1 year ago

0 Bill Johns over 1 year ago

TI__Guru* 75656 points

Hello

Yes this low a voltage could be a problem and would need to take a closer look at the ripple.

Do you have any info on the ripple freq? Also what is your charge current?

0 LeddeL over 1 year ago in reply to Bill Johns

Prodigy 20 points

Hi,

In the datasheet is stated it is measured at 20mhz bandwidth. But probably due to the switching frequency the noise would probably in the 100 to 500 khz range I guess.

Charging current would be 250 to 300mA.

Best regards

0 Bill Johns over 1 year ago in reply to LeddeL

TI__Guru* 75656 points

Hello

I suspect the ripple freq is high enough that it will not cause a problem, loop bandwidth low, sleep has a deglitch time of the sleep circuit and filter caps.

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BQ25173: BQ25173 in combination with IRM-01-3.3