BQ25703A: Application issues with BQ25703A

Hi tiger,

Does the inductance of BQ25703A require a freewheeling diode? Taking BQ25703A operating in buck as an example, as shown in Figure 1, if a freewheeling diode is not added, will the reverse electromotive force generated by the inductance damage the MOS transistor of Q2 when Q1's MOS is turned off? If Q2 is not damaged, what is the reason? Thank you.

Hi, Susan,

the MOSFET has a body diode, which can serve as that purpose. 

Regards,

Tiger

ok,thanks

Hi Tiger

BQ25703A is only used to charge the battery and not for system power supply. Can MOS transistor Q7 in the schematic be removed

Hi Tiger

The design of this schematic does not include Q7, so it is uncertain whether there will be any unknown risks

Hi Tiger

I would also like to ask, what is the function of the CHRG_OK pin on the BQ25703A chip? According to the manual, when there is no input voltage at the input terminal of BQ25703a, the CHRG_OK pin is at a low level. When there is voltage at the input terminal of BQ25703a and it is between 3.5V and 24.5V, and other conditions are met, the CHRG_OK pin will become high level. However, I have found that the CHRG_OK pin remains at a high level during testing. Please note that the CHRG_OK pin is externally pulled up to 3.3V through a 10k resistor

Hello,

Due to the U.S. holiday our responses will be delayed, sorry for the inconvenience.

Sincerely,

Wyatt Keller

Hi tiger

May I ask if BQ25703A can automatically reduce power when the temperature of BQ25703A or its surrounding MOS tubes is high during battery charging? What is the schematic diagram for achieving power reduction? Is it done through the PROCHOT pin, Thank you very much

Hi, Susan,

There is no such a function inside the chip, you will need to implement by external circuitry. 

Thank you, 

Regards,

Tiger

Hi tiger

ok, thank you very much

Hi Tiger

I have another question to ask, When debugging BQ25703A, I found that there was a high overshoot on the SW waveform as shown in Figure 1. Then I tried to add an RC filter circuit to the SW pin as shown in Figure 2 to reduce this overshoot, but I found that the overshoot became more severe after adding the RC filter circuit. I don't understand why

Hi Tiger

I have another question to ask, When debugging BQ25703A, I found that there was a high overshoot on the SW waveform as shown in Figure 1. Then I tried to add an RC filter circuit to the SW pin as shown in Figure 2 to reduce this overshoot, but I found that the overshoot became more severe after adding the RC filter circuit. I don't understand why

Hi Tiger

zhong susan said:

Then I tried to add an RC filter circuit to the SW pin as shown in Figure 2 to reduce this overshoot, but I found that the overshoot became more severe after adding the RC filter circuit. I don't understand why

Is this situation related to the value of RC, the grounding of RC to PGND, and the size of the area connected to the ground by RC?

Hi tiger

thank you very much