quote "So I'm guessing the driver will continue to charge until the set current is reached and then move onto the next step"
you have confused two functions of the modern stepper driver
the stepper driver uses a combination of two control systems
the first part
could be an up/down counter controlled by the step (clock) pulse and the direction ( count up / down ) control
the output of the counter is the address input to a read only memory used as a lookup table (code converter)
the output of the lookup table then controls the two H bridges that switch the currents that passes through the coils
these days the up/down counter and look up table is emulated by a micro controller
if the stepper supply voltage was equal to the motor voltage this would work for full and half step patterns
the second part
the "chopper current control" circuit has an internal clock oscillator running at a higher frequency than your maximum step frequency
a flip flop is first set by an internal clock pulse , switching on the supply to the motor coils
when the current measured as the volt drop across a fractional ohm resistor (that connects the H bridge to the negative supply)
is equal to the reference voltage that's used to set the current , the flip flop is reset , switching off the current to the coil
the duration on the on-time depends on the reference voltage, the drivers motor supply voltage & coil inductance
the current is only turned on again by the next internal clock pulse
by adjusting the reference voltage that controls the current according to the current step
you can generate the magnetic fields for micro stepping
John
PS