BQ32002 Application problems

kerr chang

Other Parts Discussed in Thread: BQ32002

Hi Sir
I will use TI RTC BQ32002. I have questions.
1 : How to choose Crystal PPM? 32.768K +/- ?PPM ?
2 : I will use CR2450 battery for Backup power. How long you can use for CR2450 on Backup power ( month or day )?
SPEC have show backup supply current : 0.9-1.5uA
3 : How many PPM for BQ32002 on one day?

Thank you so much!!

over 10 years ago

0 Arvind Sridhar over 10 years ago

TI__Mastermind 24205 points

Hi,

This device does not belong to the clock and timing product line. I have forwarded your request to the applications engineer who might be most familiar with this device.

Regards

Arvind

0 Ryan Kehr over 10 years ago

TI__Guru 55605 points

Hello!

1) We used the following crystal with specifications of +/-35PPM (pre-calibration). The device has a calibration feature as described in the datasheet.

http://www.sellcrystal.com/pdf/kds/crystal_resonators/smd_tuning_fork_crystal_resonators/sm-26f.pdf

2) Take the Amp Hour rating (there are several CR2450 batteries of different ratings on the web) of the battery and divide it by 1.5uA. This is will give you the approximate run time.

3) I am not 100% sure how to answer this. Oscillator error can be calibrated out as described in the datasheet, but temperature drift could result in error beyond this. This would be dependent on the temperature stability of the cystal chosen.

0 kerr chang over 10 years ago in reply to Ryan Kehr

Genius 4075 points

Thank you so much!!

Clock & timing

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BQ32002 Application problems