Part Number:BQ25895
Hi there
I have a question regarding the suitability of the BQ25895 in an application that may have repetitive switching between supplying power from the battery and VBUS.
The following setup is the worst case:
1/ VBUS is an AC supply that is rectified and unsmoothed. This supply can provide any current drawn and a has a peak voltage of 14V. The frequency may be between 1Hz and 200Hz.
2/ VBATT is a very low impedance cell at between 3.5 - 4.2V
3/ VSYS has a load that may be between 0mA and 2000mA.
4/ VINDPM is set so that it will charge the battery when there there is power available, up to a maximum of the charge current limit that is set. For example VINDPM = 5.5V.
In the above scenario, with a VSYS load of 2000mA, VSYS will be supplied some of the time by VBUS (and spare power used to charge the battery) when the part of the VBUS cycle is above the VINDPM threshold. The rest of the time the power will be supplied by the battery.
My testing so far shows that with 20uF or so of output capacitance, there is a small dip in the output when internally is it switching between supplies. Adding extra capacitance on the output resolves this issue.
My question:
Is there any particular issue with running the BQ25895 in this configuration, given the ORing occurring internally will be repetitive and continuous, instead of much more infrequently. I was thinking that this would create slightly more stress on the internal FETs due to the repetitive nature.