Hi, I am using MP2720A. My circuit needs a 5V. So I am thinking to get it from IN pin. What I want is that when input USB source is available, it charges the battery as well as outputting from SYS and I get 5V directly from IN. When input USB source is absent, I want the battery to power SYS as well as the internal booster so it can output 5V at IN too.
So I enabled booster. But it doesn’t work as expected. What I have seen is that when input source is connected, the battery is not charged. And if I removed the battery, there is also no SYS. Does that mean when the booster is enabled, external input USB is always no use?
Thanks.
Jionghao
Hello Jionghao,
Are you able to send a schematic to review on this issue?
From what it sounds like, you are expecting the booster to provide power from SYS but the battery doesn’t charge when the input source (USB) is connected, and the booster is enabled. Also SYS doesn’t seem to output 5V when the battery is removed.
Here are a few possible causes worth investigating:
- If the battery is disconnected and the booster is enabled, SYS should ideally output regulated power. There could be misconfigured control settings for the booster. Measure voltages at IN, SYS, and BATT under different conditions. Then confirm whether USB power is properly supplying internal circuitry.
- There could conversely be an issue with the power path where the booster or SYS isn’t properly enabled in the absence of the battery. Check and ensure that the booster enable signal is set correctly as per the datasheet and verify if the booster needs any additional configuration to operate alongside the USB input.
- Run tests without external loads from SYS and test functionality again. Check for shorting as that would prevent SYS from further operation.
Hopefully this provided some insight. I look forward for your response.
Best,
Krishan