I was looking for a PMIC with battery charger and built-in power path when I came across one of TI's new chip. BQ25601 http://www.ti.com/product/BQ25601. while I was trying its performance and doing some tests I noticed that it cannot withstand load steps when it's working without battery and enabled charger. as long as the charger is enabled and there is no battery connected, the chip works in suspend mode and cannot respond to transient currents. although it can provide the magnitude of the current, significant deeps appear in the output at the beginning of the load step. However, the chip works perfectly with battery irrespective of how much discharge is.
Because I don't know when he is about to connect I'm after something that can work perfectly even with no battery.