Active-Low enable input driven by high voltage signal

[mspider65]

Due to the chip shortage I am trying to adapt a circuit to use what is available.
In particular, I have to replace a Step-Down which, starting from the voltage of an e-bike battery, should generate 5V.
The doubt concerns the Enable signal of the new DC-DC which is now active low.
What I have is an output (PSU_ON) which in case of ON is at battery voltage while in case of OFF it is at GND or floating.
The EN input must be less than 0,8V to enable the chip and must be above 1,8V to disable the chip.
Max Voltage at enable pin is 7V.
I thought of using the circuit you see below but I ask those who have more experience than me for an opinion if it can be good or if there is a better way to go.
In particular i have a very small footprint to accommodate everything and any suggestion to lower the number of needed component is welcome.

[iMo]

Doublecheck the max Vgs of your mosfet. With Vin=60V the Vgs will be 15V.
Otherwise zeners (for example 5.1V one) instead of the R3 and R4 would be a more rugged solution, imho.

[T3sl4co1l]

Yeah, replacing R4 with a zener is a good idea, and one in parallel with R3.  Note that you should leave R3 in circuit, not replace it -- a floating EN might take a long time indeed to turn off, if it ever does.  (Maybe this situation never occurs so it's justified to leave out; but it's a good idea otherwise.)  Its value can then be somewhat larger, so the zener takes most of the EN current and the R3 just serves to discharge the capacitance of the zener and gate.

Dual zeners in SOT-23 are common, and offer TVS ratings as well; Comchip CPDT-5V0U-HF comes to mind.

Tim

[iMo]

A potential issue with zeners could be they would need a bit larger current, imho.
I do not know what is the lowest current to see their knees nicely
Here is a sim with it.
With 60V the loss in the resistors will be 90/110mW.

[T3sl4co1l]

Leakage is not bad for 5V zeners.  I wouldn't go any lower in voltage rating, or I'd look for another method (shunt regulator, clamp into LV supply?) if needed.  But with the 7V+ ratings here this is a fine combination.

Note that current consumption can be saved by using a depletion mode MOSFET as a current source.  This draws the same current for any Vin > 5V say, rather than having to choose a resistor for Vin(min) which then passes excess current at higher Vin.  (Probably doesn't matter from a battery, where Vin won't vary much.)

Tim