questions about bq2002G IC

Max Zhegulin

Intellectual 420 points

Other Parts Discussed in Thread: BQ2002G, BQ2002

Hi all!

I work with power management IC bq2002G.

I have same question.

1. I'm going to use one of the voltage termination mode. So, I leave TS pin open. Is it correct?

2. How to determine proper charge current? I use C/2 mode (TM is mid), batery capacity is 1000 maHr and I get 250mA charge current.

3. If I didn't place thermistor, could IC start fast charge cycle after I apply power?

Thanks!

max

over 14 years ago

0 Chris Glaser over 14 years ago

TI__Guru**** 151290 points

1. The IC still uses the TS pin to determine pack temperature to determine is charging is safe, etc. With a PVD termination IC, it simply does not use the TS pin for dT/dt termination. A resistor/thermistor is still required on TS to put the pin in the proper voltage range. If you do not want to use a thermistor, simply use a resistor. Note that there will be then be no pack safety with regards to temperature--if the pack gets too hot during fast charge, the charger will keep charging.

2. The charge current is set only by the external constant current source. The bq2002 does not set or know the charge current. There is no input on the IC for this purpose. The bq2002 simply controls the CC pin to turn on or off an external current source. This source should be set to your desired fast charge current.

3. You must have the proper voltage on the TS pin for the IC to function. This voltage can be from a simple resistive voltage divider.

0 Max Zhegulin over 14 years ago in reply to Chris Glaser

Intellectual 420 points

Chris, thank you for your quick answer.

But I have one more question.

I'm going to work with 2 batteries, so voltage after divider is always below 2V.

Should I remove divider and connect directly to Vbat pin for proper usage?

0 Chris Glaser over 14 years ago in reply to Max Zhegulin

TI__Guru**** 151290 points

If you are charging 2 series nickel cells, they will charge to around 1.5V each for a total pack voltage of 3V. You will then need the divider as specified by the datasheet.

Are your 2 cells in series or parallel?

0 Max Zhegulin over 14 years ago in reply to Chris Glaser

Intellectual 420 points

>> Are your 2 cells in series or parallel?

I have two cells in series.

0 Chris Glaser over 14 years ago in reply to Max Zhegulin

TI__Guru**** 151290 points

Yes, so then you would need the divider, since your full charge voltage would be about 3V.

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questions about bq2002G IC