A writing current circuit (42) supplies a controlled electrical current to a laser diode (34) for recording data swiftly onto a DVD (16). A plurality of thermometer code registers (52) respectively store numerical values. A current control register (58) receives a numerical value from one of the thermometer code registers (52). Serial data specifies a sequence in which individual thermometer code registers (52) supply values to the current control register (58) thereby causing the writing current circuit (42) to supply a particular electrical current waveform to the laser diode (34). A plurality of current sources (62) respectively receive a single output signal from the current control register (52) which activates or deactivates individual current sources (62) for supplying a particular quantity of current to the laser diode (34).
