BQ24192: BQ24192

Charge can be deactivated via the I2C bus, but the system has not booted yet when the power is turned on to do this, since the default charge is on. This is the problem. In my scheme, the BQ24192 powers several tps63020, when 12 volts power is turned on without a battery, chip Inductors begin to squeak and Vsys voltage drops to 1 volt, this problem is not observed on all devices. Tell me how it can be circumvented?

I'm sorry, CE pin manages this function, thanks.

Hello Nik,

The bq24192 perform the following checks at start up:
-Poor source detection
-Power up the internal REGN after 220ms delay
-Input current detection

If the latter checks pass, and charge is enable (/CE pin pulled low), then charging will begin. If the /CE pin would be pulled high by an external pull-up, for example the SYS output, charge would be disabled after start-up, and the host then would have control to enable charge after initialization.

Having said that, if the SYS voltage at start-up is less than 2.2V (which is the case when no battery is present), the device performs its soft-start sequence and sets the input current limit to 200mA and attempts to regulate SYS. Once SYS rises above 2.2V, the device begins using the input current limit set by the application (ILIM pin/input current detection).

If there's a load on SYS (for example, several buck-boost converters), the device might enter input voltage limit or input current limit and not be able to complete the soft-start sequence. This is most likely why you are seeing the SYS output drop to 1V at start-up.

Also, if you are hearing inductor whining, the device is most likely unstable and oscillating.
Items to verify are the following:
-Have you verified the output of SYS on the scope to verify if the output is oscillating?
-What's the current rating of your inductor? Inductor might be saturating, but if the device is in start-up, current through inductor shouldn't be high enough at this point.
-Is your PCB layout following the datasheet guidelines for the high frequency loops (PMID and SW in particular)?

SYS output did not look at the oscilloscope, inductance 2.2 μH, printed circuit board with minimum lengths of conductors. I want to note that when power is applied to bq24192, its load is turned off, and excitation starts when the load is switched on. Also the CE pin is connected to the ground.