Tool/software:
Hello,
Hope all is well with you.
I am facing an unexpected issue on BQ24090. We are using in couple of products, so addressing this issue would be highly appreciated.
Design approach:
I have a BQ24090 to charge a single cell Li-Ion. I hooked up an NTC (10K @25C with Beta= 3380 close to battery) to TS pin. I use a BJT to short the NTC whenever I want to measure the battery voltage/presence.
Test:
1- We put the Board in a thermal chamber tested it from -5C to 65C.
2- Wrapped the battery with a heater and put the board in its housing (It's a sealed plastic) and heated up to 65C.
3- Replaced the NTC with a POT ranged from 2K to 40k.
I tried slow ramp up/down (~1C/sec) and fast ramp up/down (~10C/sec) as well as using the BJT (considered to be in fraction of seconds).
Results:
Almost same results in all tests.
Rising Temp: The IC stops charging at ~60C (TS voltage = ~160mV, NTC = ~3.2k).
Falling Temp: It resumes charging at ~30C (TS voltage = ~410mV, NTC = 9.1k).
Issue:
1- What I see in the the datasheet is that BQ24090 should be stop charging out of (0C to 45C) with a standard 10k@25C NTC with Beta 3370.
The results are contradicting this fact.
Also in the user guide available in the website (Link below), it is mentioned that BQ24090 similar to the other ones stops charging when the Voltage is ~150mV, which represents ~60C.
https://www.ti.com/lit/ug/sluu392a/sluu392a.pdf?ts=1739540985781&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ24090%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Dapp-null-null-GPN_EN-cpc-pf-google-wwe%2526utm_content%253DBQ24090%2526ds_k%253DBQ24090%2526DCM%253Dyes%2526gad_source%253D1%2526gclid%253DCjwKCAiA8Lu9BhA8EiwAag16b3Hd1BXJS3aXyKGnh3m6u9a0I4FDZB2NJbN7IlI_xCiEuK3cwM1mChoCMFsQAvD_BwE%2526gclsrc%253Daw.ds
Please verify I should expect which temp as HIGH Temp threshold. 45C or 60C?
2- The Hysteresis should be not significant. However, I see large gap down to 30C to make the charger resume charging.
Please let me know about your thoughts on this as well. Since it is considerably concerning to us.
I hope I have added all the info you need.
Any more question, would be happy to answer.
Any fast and informative response will be highly appreciated.
