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TPS2121: Run two in parallel to double the current?

Part Number: TPS2121
Other Parts Discussed in Thread: TPS2120, TPS25947

I likely will need a little more than the 4 to 5A offered by a TPS2121.  6A should do it. 

Can I put two TPS2121 or TPS2120 in parallel and tie the outputs together?

Note: My two input voltage rails are 5V#1 and 5V#2.

I was thinking that I could share the resistor divider networks for common PR1, OV1, IN2 and OV2 inputs.  That would reduce variations for those functions.

Note sure about the CSS capacitor.  I could probably use separate "identical" resistors for the ILIM.

Also, I could use either a TPS2121 to sense the two voltages or TPS2120 and a select control line, a "PWR GD" from a previous stage 12V-to-5V regulator.

Since the these devices have internal voltage references, any differences in the voltage references and comparators between two devices would show up as slight different transition times on the outputs.
While my two 5V inputs are pretty close in value, they come from two different sources so I'm sure they are not exactly the same and therefore when the outputs are changing from one source to another I could have slightly different 5V outputs tied together for a short time.

I see a previous post "TPS2121: larger continue current solution."

I am a digital designer and FPGA programmer.  My analog skills are decades rusty.

thanks

  • Hello Jonathan,

    We don't recommend paralleling muxes. The main issue with paralleling devices is that Ron and timing characteristics may vary slightly from device to device which could cause some unexpected behavior such as one turning on before the other. If one were to turn on before the other then a single device would need to handle the load and could hit the current limit and TSD. This event could occur again during a switchover event.  

    You can use load switches with the PGOOD signal from your regulator to create a pmux. The link below (from the post you mentioned) explains more about power multiplexing with load switches and efuses, and i've also linked the product folders for both. We have numerous load switches that can operate at and above 6 A continuous output current. We also have an efuse TPS25957 that supports up to 5.5 A that can be set to pmux with the body diodes.

    Power Multiplexing Using Load Switches and eFuses (Rev. A)

    Load Switch Product Folder

    Efuse Product Folder

    Regards,

    Kalin Burnside

  • Thanks.  Looking at the TPS25947 eFuse (a pair).  Also, these can be run in parallel too if I ever needed more current.