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Tool/software:
Hi,
Setup:
we have used BQ24296MRGER as the BMS of a portable device. There is an MCU in the device which is the host device controlling the BMS.
The MCU and other peripherals in the device runs on the a power supply powered by SYS output of BMS.
We also have a switch at the QON pin of the BMS which turns the device ON.
We have added a gating using the firmware to disable BATFET, if a USB source is plugged IN and the QON was not pressed, the MCU forces to disable the BATFET.
Issue Condition:
Now the issue we have is that, when the device(with battery) is OFF, and a USB is plugged IN and QON not triggered. The device turn ON and then disables BATFET as in the firmware and turns OFF.
But then upon triggering the QON, the device is not turning ON. With and without USB connected, it wont turn ON again.
It turn ON only if battery is unplugged and plugged back. After this it works normally?
I have measured the voltage at SYS and it shows 3.6V.
Question:
Why is the device not turning ON even after QON is triggered?
even after the BATFET is disabled, why is the SYS showing 3.6V?
Hello Arjun,
We are looking into this now and will respond by the end of the day.
Sincerely,
Wyatt Keller
Hi Arjun
Checking on the BATFET OFF condition and QON not triggering, will try to get you and update tomorrow.
SYS showing 3.6V -- This would be minimum SYS voltage with a discharged battery. What is the battery during this condition, discharged or BATFET OFF?
Hi Arjun
Why is the device not turning ON even after QON is triggered?
The BATFET OFF condition could be caused by the I2C, a couple of things to looks at:
1.) I2C command to turn off BATFET - Disable Watchdog then Disable BATFET -- verify that there is no other I2C communications after this, the I2C need to be quite.
2.) Source voltage for SCL and SDA pull up - does the pull up voltage drop or glitch after BATFET turns off?