To take an input voltage of 24VDC ±10% and drive 1A through as many LEDs in series as the maximum output will allow, the circuit shown in the schematic diagram below uses the ONO-based constant ripple concept.

LM3404 Constant Ripple LED Driver circuit schematic

The average current controls the luminous flux and dominant wavelength (or color temperature for white LEDs). Because the constant-ripple LED driver fixes the valley of the inductor current and also fixes the current ripple, it’s much better at controlling average LED current over changes in both input voltage and changes in output voltage. [Circuit’s schematic diagram source: National Semiconductor Application Note]