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TPS62142: TPS62142

Nikolai Nikolov
Prodigy 160 points
Part Number: TPS62142

Hi,

I would like to enquire about the threshold levels for the TPS62142RGTT (DC/DC converter)  EN input.  It is not clearly specified in the "TPS6214x3-V to 17-V 2-A Step-Down Converter in 3 × 3 QFN Package" document.

What I gather from the table in Chapter 7.5 of this document,  the input is considered high if the applied voltage Vh is 0.65V (typical) to 0.9V (minimum)?!  And is considered low if Vl is 0.45V (typical) to 0.3 (minimum)?! 

So how to interpreted this?  What the EN input voltage should be to Enable the DC/DC converted and what it should be to Disable the converter?

My problem is that my external 15V power supply, after being switched off, still holds about 5V for a while and causes incorrect shutting down of my device which uses internally TPS62142RGTT and TPS62143RGTT DC/DC converters.

The two DC/DC converters are so good that they could keep my device ON. even when the external power supply is OFF for quite some time.  As a consequence I also experience HW reset, when the external power supply is switched off instead of full shut-down.

As a potential solution I would like to connect the EN inputs of the DC/DC converters to a voltage resistor divider, so when the external power drops below certain level (5V for example), the DC/DC converters to be disabled.

Please, advise!

Thank you for your help!

Best regards,

Nick

  • 0
    TI__Genius 14876 points

    Hi Nick,

    You need to interpret those values like the following. In the system is implemented an hysteresis on the EN pin to avoid switching from one state to another when the  voltage applied on the EN pin is slow enough.

    VL typical: .0.45V means that the typical value found in tests is the following.

    I think you should have a look at this App Note, it also works for shutdown: precise EN pin threshold

    What you could use as a resistor divider for EN is a divider by 15. When VIN=15V then EN=1V, then you will have your system on. When VIN=5V, then VEN=0.33V the system will be off.

    Thank you very much!

    Best Regards,


    Dorian

  • 0 in reply to Dorian Brillet de Cande
    Prodigy 160 points
    Hi Dorian,

    Thank you very much for the quick response!

    Best regards,
    Nick