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TLV710: priority of EN

Ryoma Ohashi
Expert 5145 points
Part Number: TLV710

Hi team,

In the AM62x SK EVM's schematic, this device is used to supply both 3.3V and 1.8V selectively.

It look like EN2 is always high, and by controling EN1, it can switch the output of 3.3V or 1.8V 

Does this device have a priority in the enabling function?

In other word, does the output2 stops when both EN1 and EN2 is high?

Regards,

Ohashi

  • +1
    TI__Guru 50025 points

    Hi Ohashi-san,

    The two channels are independent, so neither output is affected by the other channel's enable signal. I haven't seen this device used like this before, but what I think is happening is that when EN1 is pulled high, channel 1 (3.3V) allows more current through its channel to bring the output up to 3.3V, and since channel 2 (1.8V) cannot sink any current, the output stays at 3.3V. In this case, channel 2 is still enabled but its channel is closed because channel 2 wants the output to come back down to 1.8V but has no way of doing so. Then when EN1 is pulled back low, channel 1 closes its channel and R99 bleeds off the extra charge until the output reaches 1.8V and channel 2 resumes regulation. 

    I think the only reason this works is that the output voltage of the two channels are separated by enough voltage. If they were both targeting roughly the same nominal output voltage then I would expect that both control loops would interact and potentially cause instability, but since the 3.3V channel is much higher than the 1.8V channel, the 1.8V channel is effectively off even while it is enabled if the 3.3V channel is enabled.

    Regards,

    Nick