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Battery Management - Chargers Forum
BQ24103A - Only works with at least 14V VIN.
So far, I don't find the problem on the schematic. But, I don't know your test condition also. Let me summarize your test condtion. And please give more info.
1. Vin=12V, input current is about 30mA~250mA. What is the battery voltage? Is it lower than pre-charge threshold?
2. When Vin=13V~14V, Vbat will be approx. 12.5V. This is not right. Does IC get damage or bad soldering?
bq24103 is pin to pin compatible as bq24103A. The performance should be same. They both don't need a zener after 2008.
We've tracked down a couple of issues.
1. Suspecting transients on VCC that breaks the internal LDO. VTSB is either ~9V or 0.7V.
2. Suspecting transients on PG, STAT1 and STAT2 as these pins are not pulled up during initial testing.
I'll swap the BQ chip and pull-up PG,STAT1 and STAT2. Also I'll add a 15V Zener to VIN and VCC.
If we have the batteries connect they will clamp the voltage and after a while the over-voltage protection in the batteries will disconnect the batteries.
First step in testing is to apply +12V and see that we've pulsing on OUT pin. Battery detection.
Second is to check wave form on Cttc.
After that we connect the batteries. Usually around ~7V.
Charging begins and everything is ok.
Next step is to remove the +12V and remove the batteries and do the testing again.
After this step all our BQs broke. So we suspect that transients is the problem.
I'll let you know the outcome of the tests.
I added a BZX84C15 diode, 15V zener to VIN/VCC, made sure that PG, STAT1 and STAT2 is always pulled up and swapped the 27uH inductor to a 22uH to increase the margin to Isat.
Now it works as expected.
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