Abstract: A current-driven load such as LEDs or laser diodes is driven by a current driver having a two stages (or phases), the outputs of which have ripple which is forced to be out-of-phase with one another. In analog embodiments, an output (ripple or switching) of a master stage hysteresis controller is phase-shifted and scaled, and modulates the input of a slave stage hysteresis controller so that the slave stage pulls into a ripple-canceling phase. In digital embodiments, a faster of the two phases is designated “master”, maximum and minimum thresholds are set, and the slave phase's on time is based on a previous cycle's slave phase ON time, the master stage OFF time and an offset. The slave controller may “lock” to the anti-phase of the master stage (or phase). The ripple currents at the summed output of the master and slave stages substantially cancel.

Abstract: A current-driven load such as LEDs or laser diodes is driven by a current driver having a two stages (or phases), the outputs of which have ripple which is forced to be out-of-phase with one another. In analog embodiments, an output (ripple or switching) of a master stage hysteresis controller is phase-shifted and scaled, and modulates the input of a slave stage hysteresis controller so that the slave stage pulls into a ripple-canceling phase. In digital embodiments, a faster of the two phases is designated “master”, maximum and minimum thresholds are set, and the slave phase's on time is based on a previous cycle's slave phase ON time, the master stage OFF time and an offset. The slave controller may “lock” to the anti-phase of the master stage (or phase). The ripple currents at the summed output of the master and slave stages substantially cancel.

Abstract: A current-driven load such as LEDs or laser diodes is driven by a current driver having a two stages (or phases), the summed outputs of which have ripple which is forced to be out-of-phase with one another. In analog embodiments, an output (ripple or switching) of a master stage hysteresis controller is phase-shifted and scaled, and modulates the input of a slave stage hysteresis controller so that the slave stage pulls into a ripple-canceling phase. In a digital embodiment, a faster of the two phases is designated “master”, maximum and minimum thresholds are set, and the slave phase's on time is based on a previous cycle's slave phase ON time, the master stage OFF time and an offset. The slave controller preferentially “locks” to the anti-phase of the master stage (or phase) and the ripple current at the summed output substantially cancels.

Abstract: In a pulsed laser diode driver an energy storage capacitor is continuously being charged to a supply voltage Vr. When a pulse is initiated, energy stored in the capacitor is delivered to the laser diode load. The capacitor voltage Vd at the end of a pulse is used to control Vr to ensure that Vd is maintained above a minimum voltage Vm required to ensure operation of a current control device (such as FET) just above saturation. Test pulses (such as with attenuated currents or reduced pulsewidth) may be fired to determine an initial optimum value for Vr. After a test pulse, a slightly high estimate for Vr may be used and may be iterated (incremented) down to an optimum value Vm during a firing burst. A digital processor may be used to calculate and store data to optimize the performance. Various embodiments are disclosed.

Abstract: In a pulsed laser diode driver an energy storage capacitor is continuously being charged to a supply voltage Vr. When a pulse is initiated, energy stored in the capacitor is delivered to the laser diode load. The capacitor voltage Vd at the end of a pulse is used to control Vr to ensure that Vd is maintained above a minimum voltage Vm required to ensure operation of a current control device (such as FET) just above saturation. Test pulses (such as with attenuated currents or reduced pulsewidth) may be fired to determine an initial optimum value for Vr. After a test pulse, a slightly high estimate for Vr may be used and may be iterated (incremented) down to an optimum value Vm during a firing burst. A digital processor may be used to calculate and store data to optimize the performance. Various embodiments are disclosed.

Abstract: A current-driven load such as LEDs or laser diodes is driven by a current driver having a two stages (or phases), the summed outputs of which have ripple which is forced to be out-of-phase with one another. In analog embodiments, an output (ripple or switching) of a master stage hysteresis controller is phase-shifted and scaled, and modulates the input of a slave stage hysteresis controller so that the slave stage pulls into a ripple-canceling phase. In a digital embodiment, a faster of the two phases is designated “master”, maximum and minimum thresholds are set, and the slave phase's on time is based on a previous cycle's slave phase ON time, the master stage OFF time and an offset. The slave controller preferentially “locks” to the anti-phase of the master stage (or phase) and the ripple current at the summed output substantially cancels.

Abstract: A pulse forming and delivery system 10 is disclosed for forming and deliverying a pulse of electrical energy to a flashlamp 38. System 10 includes a capacitor 14 which is adapted to selectively store electrical energy from a power supply 16 and to transfer this electrical energy to flashlamp 38 when the gate portion of thyristor 12 is open. This gate portion is opened by controller 28. The total amount of light energy emanating from the laser and/or provided to flashlamp 38 is monitored by detector 42 and communicated to controller 22 by means of bus 44. When this total amount has exceeded a desired energy level, controller 22 prevents further electrical energy to be impressed upon switch controller 28 thereby, closing the gate portion of thyristor 12 and preventing any further transfer of energy to flashlamp 38.