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TPS62843: TPS628438, problem with Enable specifications

Part Number: TPS62843


I use the buck TPS628438 to transform a 5.4V input to 3.0V. Input comes from a 0.47F super capacitor, so rises very slowly. I would like to enable the buck when I reach around 3.3V/3.5V, to be sure to have 3.0V at the buck output, so I put a resistor between input voltage and the EN pin.

What I observed is not in concordance with the specification. It is written that the rising threshold is 0.8V, and the internal pull down resistor is between 425 and 500 Kohm.

What I observe is the threshold level is around 0.6V and not 0.8V, and the internal resistor is around 900kohm and not 500K.

I had calculated that I should put a 1.5Mohm resistor to obtain an input enable threshold between 3.2 and 3.6V, but I had to put 3Mohm to obtain a 3.5V threshold.

So what is wrong ?