BQ24707A: The buck converter will stop oscillating. what's happening.

user4012620

Part Number: BQ24707A
Other Parts Discussed in Thread: BQ40Z50

Hi Team,

I made a prototype of a lithium-ion battery charging circuit using BQ24707A,

but it does not work well. It only works for 14.5ms after ChargeVoltage (), ChargeCurrent () is sent from the smart battery.

Please tell me what is happening.

Please refer to the attached oscilloscope waveform.

The gas gauge of the battery is BQ40Z50.

Best regards,

Tanaka

CH1: SCL

CH2: SDA

CH3: High-side MOSFET Gate

CH4:Low-side MOSFET Gate

over 4 years ago

0 Kedar Manishankar over 4 years ago

TI__Mastermind 24075 points

Hi,

Do you have watchdog timer disabled? Run through section 8.4.1 of the datasheet as well to make sure all conditions are met.

0 user4012620 over 4 years ago in reply to Kedar Manishankar

Prodigy 30 points

Hi Kedar Manishankar,

Thank you for your reply.

The watchdog timer remains active.

Review section 8.4.1.

This board stopped working just by changing the GND pattern from the prototype board with the charger running.

Since the pattern of lowside MOSFET and GND has become a little longer, it seems that the operation does not continue like the above waveform.

Why is this happening?

Best Regards,

Tanaka

0 Kedar Manishankar over 4 years ago in reply to user4012620

TI__Mastermind 24075 points

Hi Tanaka,

The ground return of the LSFET is the most critical loop of a switching charger. The high frequency loop of the input capacitor, HSFET, LSFET loop is extremely critical and must take priority over everything else.

+1 user4012620 over 4 years ago in reply to Kedar Manishankar

Prodigy 30 points

Hi Kedar Manishankar,

Thank you for your advice.

I will use it as a reference.

Best Regards,

Tanaka

Power management

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BQ24707A: The buck converter will stop oscillating. what's happening.