BQ24296 output voltage

Krzysztof Marcinek

Other Parts Discussed in Thread: BQ24296

I have a problem with BQ24296 battery charger. Everything looks quite ok while I've got battery attached. System voltage looks ok, charging current looks ok. Device works ok with battery and no input voltage.

Strange things happen when I power on device with no battery attached. The system voltage is then only about 2V and floating. What can be the cause?

over 10 years ago

0 Krzysztof Marcinek over 10 years ago

Prodigy 210 points

When I first start the device and then detatch battery outbput volatege remaind about 4.2V so its also good.

What can be the reason I cannot start the device without battery?

0 Ryan May over 10 years ago in reply to Krzysztof Marcinek

TI__Genius 13700 points

Hello Krzysztof,

That is curious. Could you provide your schematic at the test parameters?

Also I have a few other questions.

-Is the SYS pin loaded in anyway?

-What do you mean by float? Does it simply move around and have a mean value of approximately 2V?

0 SamW2000 over 9 years ago in reply to Ryan May

TI__Intellectual 1910 points

Hi, There is a 100mA current limit when SYS is below 2.2v. This is designed to behave as soft start. If you're system demand more than 100ma input and battery is not available for supplement mode, the system may not power up. Are there components on the board that requires high current when system is below 2.2v?

0 Krzysztof Marcinek over 9 years ago in reply to SamW2000

Prodigy 210 points

I looks like that current limit is a problem. When the SYS voltage is 2V some logic pins can have invalid levels and other deviced like buck-boost converters etc. can draw some current. That way the SYS voltage cannot rise and provide valid supply volatages to other devices. Is there a way to override this limitation?

0 Krzysztof Marcinek over 9 years ago in reply to Krzysztof Marcinek

Prodigy 210 points

Can you please suggest possible solutions to solve this problem?

0 SamW2000 over 9 years ago in reply to Krzysztof Marcinek

TI__Intellectual 1910 points

Unfortunately, there is not a way to override this limit as it is part of our soft start circuit. I am surprise to know that the buck-boost does not have a high UVLO threshold.

0 Krzysztof Marcinek over 9 years ago in reply to SamW2000

Prodigy 210 points

Can you suggest other similar IC to BQ24296 that do not have this 'feature'?

Power management

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BQ24296 output voltage