Hi Ryan
here is another question for you. Do you think it is possible to parallel both outputs of the TPS7B7702 to increase the output current capability ? If yes, how would the proposed circuit look like ?
Thanks for your help.
Best Regards
Matthias
Hi Matthias,
We have two application notes talking about general application with current sharing. Please see them here:
As for TPS7B7702, current sharing is possible. You can do the sharing with the added ballast resistors for the potential offset between the two outputs. There are a few things that need attention when doing the current sharing with this device.
1. If you parallel both outputs of TPS7B7702 together without ballast resistors, you will lose the diagnosis functions from /ERROR pin. Assuming you would like to have a total current of 400mA and set the Rlim resistors on both channels to output 250mA (leaving a 50mA margins on the output capacity), the challenging part is to balance the current. If you simply using feedback resistors to set both output to be the same voltage and then parallel them to source the 400mA current, during current ramping, you will see that /ERROR pin is asserted low due to current limit being hit by one of the channels. The output channel with higher output current will have a sense pin voltage being pulled up to 2.55V as the channel is under current limit. For this application, you will still have the reverse current protection/ reverse battery protection. The benefits of this method is to not include ballast resistors, reduced dropped out spec comparing to single channel and possible output more current that a single channel cannot provide.
2. If you think to have the ballast resistors together with the Rlim resistors, you may be able to adjust the two channels and balance your currents without hitting current limit.
More details on how to calculate the ballast resistors can be found in the application notes. Please let me know if you have any questions.
Regards,
Jason Song
