Patent ID: 7504746

Claim:
A differential load driving circuit comprising: a plurality of power switches coupled to a load and for transferring power to said load, wherein each power switch of said plurality of power switches is either fully on or fully off; a plurality of power switch driving circuits for controlling switching states of said plurality of power switches respectively and for selectively coupling at least one power switch of said plurality of power switches to a PWM (pulse width modulation) signal so as to enable a PWM powering mode, said power switch driving circuits comprising a first switch driving circuit comprising: a first switch that couples and decouples a first current source from said load; a second switch coupled in parallel with said first switch and that couples and decouples a first power switch to Vcc; a third switch coupled in parallel with said second switch and that couples and decouples said first power switch to said PWM signal; a fourth switch coupled in parallel with said first switch and that couples and decouples a second power switch to ground; and a fifth switch coupled in parallel with said fourth switch and that couples and decouples said second power switch to said PWM signal; and a controller for controlling said plurality of power switch driving circuits and for either selecting said PWM powering mode in which said PWM signal controls said at least one power switch or selecting a linear powering mode in which said first current source supplies current to said load, and for controlling a switchover point between said PWM powering mode and said linear powering mode according to a predetermined threshold to achieve a specified ripple current of said load.