TPS54531: EN enable pin voltage

Rod Brick

Part Number: TPS54531

Does a voltage appear at a floating EN pin of the TPS54531? Are the internal current sources simply blocked with nowhere to go? If the EN pin is tied through a diode (anode on the pin) and a resistor to ground would the 1uA to 4uA current sources somehow create a voltage that would exceed the diode Vf so the current flows through the diode and resistor to ground? Or with the diode and resistor connecting EN to ground would EN still be floating with no voltage on the pin?

Thanks for any help.

over 4 years ago

0 Sam(MPAA) Zhang over 4 years ago

TI__Mastermind 19080 points

Hi,

Yes, a voltage will appear if EN is floating. The floating pin will eventually reach the same voltage to which the current source is tied to on the "upper side". Then there will be no current flow at all.

If a diode is connected, the situation depends on the I-V curve of the diode. Usually a few micro-amperes is really a small current for the diode. I think Vf will be a low voltage, then the device may not be enabled by EN floating.

Regards,

Hao

0 Rod Brick over 4 years ago in reply to Sam(MPAA) Zhang

Intellectual 580 points

Thanks, Hao

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TPS54531: EN enable pin voltage