BQ25898: How to set the TS pin's potential to simulate a good temperature ?

Hulu

Part Number: BQ25898
Other Parts Discussed in Thread: BQ25798

Tool/software:

Hi,

We're using BQ25798 IC but facing some issues. We always get "not charging" status, even on default mode (without programming our own configuration to the chip). By dumping all registers' contents, we find that TS_HOT_FLAG = 1. and at the "STAT" pin, the signal toggles at 0.7 Hz. In order to reduce eventual problems, we tried to force the potential on the TS pin so that we're on the good range of TS, with two identical resistors of 47 K connected between VREGN and GND. We measured VREGN = 5 V and effectively got the voltage on TS pin near to 2.5 V. Please give some information on what is the corresponding voltage range for a good temperature. Can we leave 2.5 V on the TS pin? Why is the TS_HOT_FLAG set to 1 with this voltage?

Thanks a lot!

Hulu

PS: I attached the registers' value BQ_registry_read.xlsx

24 days ago

0 Wyatt Keller 23 days ago

TI__Guru** 103795 points

Hello Hulu,

We are reviewing your data and will respond by the end of the day.

Sincerely,

Wyatt Keller

0 Ning T 23 days ago in reply to Wyatt Keller

TI__Guru 51901 points

Hello Hulu,

1. Please visit https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/874557/faq-bq25890-faq-bq2589x-schematic-review-and-pcb-layout-design-tips for BQ2589X Schematic Checklist. If TS function is not used, please connect as suggested to set VTS to 50% REGN.

2. For RT1 and RT2 calculation tool, please refer to http://www.ti.com/lit/zip/slurax7. BQ25898x is similar to BQ2589x. Please plug in the thermistor information for the specified temperatures (T1 and T5) accordingly. T2 and T3 are dependent on RT1 and RT2.

Thanks,

Ning.

0 Hulu 23 days ago in reply to Ning T

Prodigy 30 points

Thanks a lot Ning.

"suggested to set VTS to 50% REGN": We already put two identical resistors to get 2.5 V on the TS pin, but we had this toggling signal at 0.7 Hz on the STAT pin. We just put a 5.1 k and a 7.5 k (7.5 k coming from the two resistors 30.1 k and 10 k NTC in parallel) and we got thus more voltage on VTS. We don't see any more STA toggling. But now the problem is that since we haven't write our own configuration on the charger, it should be in the default configuration with 1 A of charging current. However we read only 200 mA. Is it normal?

Thanks in advance.

Hulu

0 Jeff F 22 days ago in reply to Hulu

TI__Guru**** 152646 points

Hi Hulu,

V(TS) = 50% of VREGN with matching resistor divider. If battery voltage is below the LOWV threshold, the charger is in precharge which defaults to 200mA.

Regards,

Jeff

0 Ning T 3 days ago in reply to Jeff F

TI__Guru 51901 points

Hi,

We have not heard from you for a while. The thread is considered solved and closed.

Thanks,

Ning.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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BQ25898: How to set the TS pin's potential to simulate a good temperature ?