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In tps65090 VSYS and VAC

I am palnning to use tps 65090 for an application 

where in I require to run the system for 1/2 hour after power off
for this I am planning to use this Ic . I am planning to use a  2s li ion battery (net voltage 7.4 V), which will be  getting charged till the main supply is available.

my requirements is to supply with  
two   5v 800mA  ,
one 5V 1.2 A
one  5v  1A  .            that is a total of 3.8A  

1) In the data sheet I found that there are two supplys required one is VAC  and Vsys  for each LDO and each DCDC .
because it is written in the description that 

The device automatically switches adapter or battery power to the system load. The battery is connected to the
system by default during power up or if the adapter power is not available.

In this above statement what is the word  system referred to ? 

Does it include  DCDC and LDO 

DO I have to supply a separate VSYS voltage ?

If no , My supply voltage is going to be I guess 12v source will that be ok .

please help me understand this .


  • Hi Noble,

    The output voltage to the "system" is often referred to as VSYS, and is the a universal output voltage from the power-path, which can be sourced by either VAC or the BAT depending on which voltage is higher. The power-path chooses which source to direct to VSYS, and from there VSYS can be used to power the DCDCs and LDOs.

    This is slightly more clear in the EVM schematic where VSYS is just a net name on the top right, used to supply VSYSC, VSYS1, VSYS2, etc. on the PMIC.