bq24650 no charging current when connected 12.6 lead acid battery

ahmed elmansy

Other Parts Discussed in Thread: BQ24650

hi guys I am using the typical application in the bq24650 data sheet but i used fbq20n06 instead of 2788 mosfet also I did not use the charger enable mosfet 2n700n at all

all the input conditions are met mppset =1.3 and ts=1.9 vreg=3.3 and ts=3.3

any support here

over 10 years ago

0 Smriti B over 10 years ago

TI__Expert 5565 points

Ahmed,

Could you elaborate on the problem? Is the SMPS switching but no current is delivered to the battery? SMPS does not start up at all (no switching)? Please attach a scope capture of the following nodes: PH, HIDRV, LODRV, SRN. Also, please include the voltages of all the pins when the device is in this state.

0 ahmed elmansy over 10 years ago in reply to Smriti B

Prodigy 70 points

Sure sir i will scope the nodes and send them once i reach the lap

0 ahmed elmansy over 10 years ago in reply to ahmed elmansy

Prodigy 70 points

scope captures 7-5-2015.docx

0 ahmed elmansy over 10 years ago in reply to Smriti B

Prodigy 70 points

1376.scope captures 7-5-2015.docx

0 Smriti B over 10 years ago in reply to ahmed elmansy

TI__Expert 5565 points

Is this with the battery plugged in? What does it look like without the battery plugged in? What is your input voltage? What is your battery voltage? Can you share the schematic? You mentioned ts = 1.9V and ts = 3.3V. Which one is correct? Could you also include a scope capture of the PH node? Also, please provide LODRV signal with MOSFET connected.

Are you using the bq24650 EVM or is this on your PCB?

0 ahmed elmansy over 10 years ago in reply to Smriti B

Prodigy 70 points

All what u are asking about is in the attached word file all these scoped signal are with out connecting battery ts is 1.9 and termen is 3.3 my vcc is 21.1 v i want to know why my lowdrive signal looks good with out connecting mosfet and is messed up when connecting mosfet i also wonder there are ni high drive signal my sechmatic is just the typical application one more thing does the 20n06 fits this ic cuz i used it instead 2788

0 Smriti B over 10 years ago in reply to ahmed elmansy

TI__Expert 5565 points

I don't see the PH node scope capture in your document.

If the battery is not connected, there won't be any charging. Your SRN graph looks like Fig 20 from the datasheet. You have no battery, so the charger is in battery detection mode (discharging and charging the SRN node). What do the waveforms look like with the battery connected?

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bq24650 no charging current when connected 12.6 lead acid battery