LSF0108-Q1: Higher Output Voltage than Supply Reference Voltage of Level Shifter

I have some more info. I noticed how finicky the EN pin can be. I earlier had a GPIO driving EN as a push pull. The currents from GPIO to the EN were significant enough to make the output drive to 1.779V. After I switched the EN to a open-drain, I saw the output of the A channel go up to 1.429V.

Better, but still unclear to me why it's not regulating at 1.2V.

Hey Phillip,

Do you have any load on that pin? Or are you just measuring with an open circuit?

The voltage can drift up a bit from the normal operating voltage if there's nothing connected.

You are right, that if there is a load the voltage drifts down to about 1.34-1.35V. Even then that is quite high, right?

Hey Phillip,

Can I get a schematic of your circuit to make sure we are on the same page. Also have you probed the Vref_A supply? 

Hey Phillip,

That is higher than I would expect - I agree with Dylan -- it's likely that the Vref_A supply is increasing some.

Here's a simulation of the circuit with a very light load (1pF):

I'm not usually an advocate of 'betting the ranch' on a simulation, but I've found that I can see this type of 'drift up' behavior using this simulation model in the past. If the part would drift up to 1.34V with a stable 1.2V VrefA, I would expect to see it here.

If the two supplies are stable, I would expect your output not to exceed ~1.24V, even without any pull-up or pull-down resistor.

I've included the Tina-TI file here in case you want to mess around with the simulation yourself:

LSF0101_1V2_to_5V0_typical.TSC