Is LSF0108 ICC 6uA(Typ)?

Hello Nakai-san,

The flow of current through the gate of any MOSFET is extremely low - usually in the fA range or less. I think the 'power consumption' of the LSF devices is very misleading since this is a passive device and doesn't actually consume very much power by itself.

The supply current for the LSF0108 is calculated from the bias current at the supply input. There's a detailed video explaining this located here:

It's best to calculate the required current based on your supply -- for example, if you are translating 1.8V to 5V, then you could expect to get:

(Vcc1-Vcc2-Vtn)/Rbias = (5-1.8-0.85)/200000 = 11.75uA

It's also important to note that the current generated into the LSF bias circuit will be coming back out of the LSF and sinking into the lower supply -- not all supplies can handle this, so it's important that it's accounted for in the system design. If there is a device on the 1.8V side that is using the 11.75uA, then the LSF is essentially not using any power (except for some very minor resistive losses).

Here's an example:

You can see in the above image that the current is not consumed in the LSF device but continues on to power the FPGA. This is an extremely common way to use the device, and will minimize system power consumption.  Note that the resistor (200kohm) will use some power, and there will be a very minor resistive loss in the bias circuit (~100 ohms max).