BQ24045: using for bottom cell recarge bat. how can I select Riset

Ignasi Cairo

Part Number: BQ24045
Other Parts Discussed in Thread: BQ24040

I want to recharge a Li-Ion botton cell battery (LIR2032) with BQ24045 but the manufacture provides màximum charge corrent (35 mA) but in order to select Riset, I need Kiset factor. Do you know how to obtain it?

over 5 years ago

0 ezhao over 5 years ago

TI__Genius 10240 points

Ignasi,

The information you requested is on Page 7 of the BQ24045 datasheet.

0 Ignasi Cairo over 5 years ago in reply to ezhao

Prodigy 150 points

Thank you.
Just to make sure my understanding is correct.
1) Since charging current is 30mA, I select the option : 25<Iout > 50 mA, so the Kiset=527
2) Then Riset = 527/0,03=17,5 KOhm

So placing such resistor that will be enough? Do I need to modify any other component?

0 Ignasi Cairo over 5 years ago in reply to Ignasi Cairo

Prodigy 150 points

Thank you.
Just to make sure my understanding is correct.
1) Since charging current is 30mA, I select the option : 25<Iout < 50 mA, so the Kiset=527
2) Then Riset = 527/0,03=17,5 KOhm

So placing such resistor that will be enough? Do I need to modify any other component?

0 Bill Johns over 5 years ago in reply to Ignasi Cairo

TI__Guru 65706 points

Hello
Yes a resistor value of 17.5k will give you 30mA charge current.
To terminate at 10% leave PRE-TERM (Pin 4) Open.

Also see BQ24040 Quick Start Guide at below link, much of the info will apply to the 045 also.
www.ti.com/lit/pdf/slua901

Power management

Power management forum

BQ24045: using for bottom cell recarge bat. how can I select Riset