Creating -24V @ 750 mA from a Variable DC lab supply

Edit - I realised you might want from 0V to +5V for -24V to 0V, so here is another NPN based option that might do the trick, and also does not need the -24V rail. I left the FET based circuit there anyway in case it is of interest. As noted below you might have to fiddle with values a bit, this was just intended to put the idea across.
I wasn't entirely sure whether the signal is analog or digital, as you mention digital in the title, but also an acquisition device (so I thought it may be possibly heading for an ADC) so I assumed either was possible, hence the attempt at linearity.

NPN circuit

NPN circuit simulation

Alternative Option

An N-channel FET source follower might work okay with a voltage divider on the input. Say something like a 10:1 divider for a range of -2.4V-0V at the gate. The source of the FET to 0V through a resistor and drain to +5V.
This won't be the most linear but shouldn't be too bad if you fiddle around with values a bit to adjust the desired ratios. You could maybe add a constant current source (e.g another N-channel FET with source to -24V through e.g a 5K resistor, gate tied to source and drain to source of upper FET) on the source to make it more linear if necessary.

Here is a circuit and simulation of the (more linear) constant current idea (the green line is +Vout as Vin is swept from -24V to 0V):

FET circuit

FET circuit simulation

If it is only necessary to drive the MOSFET for a brief moment, you can use a concept like this:

^{simulate this circuit – Schematic created using CircuitLab}

While the output of the comparator is high, the capacitor gets charged. Then when the output of the comparator switches LOW, the capacitor is still charged and the right plate will be pushed below 0V. The capacitor cannot discharge through the diode so it will stay charged for a while with only leakage current flowing.

Usability depends on exact specification of your components, but you can play with capacity, an extra pull up resistor and the cathode voltage on the diode.