| 摘要 |
<p>A regulator controller 2 includes a hysteretic comparator 12, 30 which controls a switch such as transistor 15 for switching current into an inductor 3. The comparator 12 has upper and lower thresholds and is supplied with a signal representing the instantaneous inductor current, and a signal representing an error between a desired an actual regulator output and output. The error signal can be detected by an accurate current monitor 36, having a comparatively slow response time, averaged and applied as negative feedback to modify the comparator input voltage and thereby control the average inductor current. An integrator 42 can integrate the error signal and have a time constant of several switching cycles. Both of the current signals can be sensed by sensing resistor 5 or by separate sensing resistors (fig 13, 5,6). The current feedback can be blocked by a gate controlled by the comparator (fig 16, 57) while the switch is on. The regulator can be arranged as a buck, a boost (fig 12) or a buck-boost converter (fig 13) and have a diode 4 connecting the output to the load. The switching regulator supplies a controllable average current to a load 1, such as series-connected light emitting diodes and permits dimming controlled by varying the voltage at control input 13.</p> |
