BQ24773: BQ24773 will not enable charging

Owen

Part Number: BQ24773
Other Parts Discussed in Thread: BQ24770, , BQ25730, BQ25723

Hello,

We have a design that uses the BQ24773 and it is almost identical to the EVM that uses the BQ24770.

We are using the 2.2uH Inductor (L1) and we have found that charging does not work when the frequency is at 1.2MHz and only works at 600kHz.

And charging also does not work at voltages below 12V when setting the switching frequency to 600kHz, where the inductor begins ringing.

Does TI have any suggestions on how to mitigate this issue?

We would like to be able to use the whole voltage range of 4.5-24V, with a 3S battery.

Thanks,

Owen

over 3 years ago

0 Khalid Bairuti over 3 years ago

TI__Expert 4780 points

Hello Owen,

When you say charging doesn't work, do you see any possible OVP conditions occurring that could be shutting down the charger? You may need to increase capacitance at the output and input in order to resolve this.

Khalid

0 Owen over 3 years ago in reply to Khalid Bairuti

Prodigy 175 points

Hey Khalid,

I do not see any OVP conditions. I do see the BATDRV go low for split second and then high and does not initiate charging.

And adding more capacitance to the input and output did not change results.

0 Tiger Zhou over 3 years ago in reply to Owen

TI__Mastermind 34775 points

Hi Owen,

Please note that BQ24773 is a buck charger, it can charge a 3S battery from an adapter voltage higher than 12V. There is no way to charge the battery if the input voltage is low.

Alternatively, you can use our buck-boost charger, such as BQ25723, or BQ25730.

I²C 1-4 cell NVDC buck-boost battery charge controller with power path and USB-C® PD OTG

https://www.ti.com/product/BQ25723

Regards,

Tiger

0 Owen over 3 years ago in reply to Tiger Zhou

Prodigy 175 points

Hi Tiger,

Understood, didn't catch that. So do guys have any reasoning for why charging would only work at 600kHz and not 1.2MHz?

Thanks,

Owen

0 Tiger Zhou over 3 years ago in reply to Owen

TI__Mastermind 34775 points

Hi Owen,

Theoretically, it should work at both frequencies. However, due to fixed deadtime, the duty cycle is reduced. The 1.2MHz takes more hit than 600kHz. Thus it is reasonable for 1.2MHz not working but 600kHz working.

Regards,

Tiger

Power management

Power management forum

BQ24773: BQ24773 will not enable charging

I²C 1-4 cell NVDC buck-boost battery charge controller with power path and USB-C® PD OTG