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TPS2115A: Power Sequencing with one Vin < 2.8 and one Vin>2.8

Richard Mcallister
Prodigy 30 points
Part Number: TPS2115A
Other Parts Discussed in Thread: TPS2114A, TPS2115

Hi All,

I'm looking to use a TPS2114A or TPS2115A to switch two voltage rails to some level translators, to allow me to control the levels. I need to switch 1.8V and 3.3V, which is covered by the TPS2115A's range. Per the datasheet, its all right to have an input of down to 1.5V, so long as the other Vin > 2.8V. 

My concern is that due to our power sequence, the 1.8V will come up before 3.3V. Since the device will not be fully on, what will be the effects? Will the device just remain inactive, or do I run the risk of burning the input? My first solution to this is to FET switch, connected the 1.8V to the TPS2115 and controlled by 3.3V. Its a little bit of a roundabout solution, but now the 1.8V input will only be supplied while the 3.3V is active.

Thanks,

Rich

  • 0
    TI__Genius 10855 points
    Hi Richard,

    Thanks for reaching out on E2E!

    You won't risk the device being inactive, or burning the input. As long as the inputs are within the maximum operating conditions of the device, you shouldn't have any issues or risk of causing damage to the device.

    If you're concerned about the 1.8V input being high before the 3.3V input, you could connect a resistor divider to the D0/D1 pins to ensure that the Dx pin stays low before the input is asserted. This will ensure that the device selects the 3.3V input before the 1.8V input.

    Thanks,
    Arthur Huang