240 may provide an indication of when driving begins by asserting the start terminal 226, and the controller 240 may provide an indication of when driving ceases by asserting the end terminal 228. Although shown as single singles, in other cases the pulse signal sent to the controller 240, the start signal sent to the LIDAR controller 110, and the end signal sent to the LIDAR controller 110 may be low-voltage differential signals (LVDS), and thus each of the pulse terminal 224, start terminal 226, and end terminal 228 may be sets of terminals on which differential signals are received or driven.

The controller 240 may take any suitable form. For example, the controller 240 may be individual circuit components constructed on the substrate 210, an application specific integrated circuit (ASIC) constructed on the substrate 210, a microcontroller constructed on the substrate 210 (with controlling software in a memory on or off the substrate 210), a digital signal processor (DSP) constructed on the substrate, a processor constructed on the substrate 210 (with controlling software in a memory on or off the substrate 210), a field programmable gate array (FPGA) constructed on the substrate 210, or combinations thereof, configured to read inputs (e.g., from the LIDAR controller 110) and drive outputs (e.g., the control inputs of the switches) responsive thereto.

Still referring to FIG. 2, having now described the components of the example system the specification turns to describing charging the inductor, driving the inductor current to the array of diodes 102, and recirculating the inductor current in relation to the example components. Consider that the diode driver circuit 104 is initially powered up and has yet to drive any current to the array of diodes 102. In example systems, the LIDAR controller 110 communicates with controller 240 conveying information such as a current setting which sets or dictates the predetermined threshold during charging, for example a current setting of between and including 2.25 Amps to 10 Amps. The LIDAR controller 110 may communicate a pulse width which sets or dictates the predetermine period of time, such as between and including 3 nano-seconds (ns) and 20 ns. The LIDAR controller 110 may communicate a row selection. Once the example communication is complete (e.g., the bits are latched in and provided to the controller 240), the controller 240 may close the designated row switch(es), and await assertion of the pulse terminal 224.

Once the pulse terminal 224 is asserted, the controller 240 places the plurality of switches in a charge configuration. For charge configuration in the example system the controller 240 makes conductive or closes the high-side switch 242 by asserting the control input 256, makes conductive or closes the shorting switch 246 by asserting the control input 268, and makes non-conductive or opens the low-side switch 244 by de-asserting the control input 262. Thus, the voltage supply coupled to the power supply terminal 216 is coupled to the inductor 206 through the high-side switch 242, and the inductor 206 is coupled to ground through the shorting switch 246. Current is generated through the inductor 206 as the field around the windings of the inductor 206 grows. Charging of the inductor continues until the inductor current reaches the predetermined threshold. In the example system of FIG. 2, the controller 240 monitors the inductor current by way of a current sense transformer 282 having single-turn primary and a secondary winding coupled to the controller 240; however, monitoring or measuring current may take any suitable form, such as a small current sense resistor in series with the inductor current, or the controller 240 being provided value of the inductor and voltage of the voltage supply, and calculating the current without an actual measurement. In any event, when the current reaches the predetermined threshold, the controller 240 transitions to placing the plurality of electrically controlled switches in a discharge configuration that drives the inductor current through the selected portion of the array of diodes 102.

Driving the inductor current in the discharge configuration may thus comprise opening the high-side switch 242 by de-asserting the control input 256, closing the low-side switch 244 by asserting the control input 262, and opening the shorting switch 246 by de-asserting the control input 268. If not previously closed, the driving may also comprise closing the selected row switch by asserting the respective control input. Moreover, the controller 240 may signal the LIDAR controller 110 that driving has begun by asserting the start terminal 226. Because current through an inductor 206 cannot change instantaneously, the inductor 206 thus drives the inductor current to the selected portion or row of the array of diodes 102. It may be possible to drive the inductor current to the selected row while leaving the high-side switch 242 closed (and not closing the low-side switch). However, in example embodiments, and for reasons of intrinsic safety, the high-side switch is opened which disconnects the voltage supply and limits the available energy that can be driven to the devices external to the diode driver 208. Since the high-side switch 242 is opened in example embodiments, the low-side switch 244 is closed to provide a current path. The controller 240 thus drives the inductor current to the selected row for the predetermined period of time. In other example cases, driving may cease based on other variables, such as the inductor current falling below a threshold (predetermined or otherwise).

Regardless of the trigger for ceasing the driving of the inductor current, the example method then transitions to placing the plurality of electrically controlled switches in the recirculation configuration, recirculating the remaining inductor current. In particular, the controller 240 closes the shorting switch 246. Given that the low-side switch 244 is already closed or conductive from the driving step, closing the shorting switch 246 effectively shorts the leads of the inductor 206 (through the ground). Simultaneously with closing the shorting switch 246, the controller 240 may also assert the end terminal 228. Thus, the remaining inductor current circulates through the inductor 206 in anticipation of the next charging event. Because the remaining inductor current was re-circulated, during the next charging event the inductor current need only be increases to the predetermined threshold, rather than generated anew from the inductor current being zero (as is the case in the initial charging after power up). Recirculating the inductor current thus increases efficiency of the diode driver 208, and the overall diode driver circuit 104. Moreover, the rate of charging and driving may be increased relative to charging the inductor current from zero each time.

The various embodiments discussed to this point have assumed that all the switches reside within the diode driver 208, and particularly that all the switches are disposed on substrate 210. However, depending on the size of the array of diodes 102, the desired voltage/current of each pulse, the desired pulse time, number of rows simultaneously driven, and/or heat and temperature considerations, the LIDAR system may implement discreet switches (e.g., FETs) external to the diode driver