I need the function of "automatic transition between two input sources", so I am considering to use LTC3126.
However, its output current is just up to 2.5A. Is it possible to connect the output of 2pcs of LTC3126 in parallel to double output current to 5A? Thanks.
Current sharing is difficult in LTC3126 as it doesn't have an external Vc pin like LTC3118. We can control the inductor current level with this pin.
Paralleling LTC3126 with additional current…
LTC3126 can be paralleled but you will have to adjust the feedback signal to balance the load current between the converters, so that will require additional external current sense circuitry.
LTC3118 is also a dual input part with 2A output current and could be a better solution if you want to parallel the converters. It will not require any additional current sense circuitry when paralleled. Also if dual input is a requirement then you could also use a prioritizer such as LTC4417 with the converter of higher output current capability. If you let us know your design requirements we would be able to suggest some possible solutions.
Thanks for your reply.
The input of LTC3118 is up to 18V and does not fit to my application. But may I know why it can be connected in parallel without external current sense circuitry?
How complicate the external current sense circuitry for LTC3126 will be?
In my application, the power circuit will be used in vehicle, the input requirement is 9-36VDC and output is 5VDC/ 5A.
There willl be two input sources, namely i.) a 9-36V automotive battery and ii.) 4 - 6 pcs of super-capacitors connected in series.
The automotive battery will have higher priority to supply power to a 5V system and the super-capacitors are used as a backup power, they can last for about 1 minute to let system shut down gratefully.
Seems LTC4418 + LTC8612 can be ok, Any other good choices?
Paralleling LTC3126 with additional current sensing and load sharing circuitry might not be a cost effective solution as well.
LTC4418+LT8612/LT8640 should work well for your design.