| 摘要 |
A switching regulator 300 comprises a tank circuit 120, a comparator 102 that generates an error signal Vc, a second comparator 104 that generates a pulse signal and a gate driver 106, and an over-current protection circuit 310. Over current circuit 310 counts the number of times that the error signal Vc rises above a preset voltage (fig 5, Vs) and enables a control signal that influences the driving signal to tank circuit 120 when the count exceeds a preset number, whereupon transistor switch 108a may be turned off to reduce the output current IL to load 130. The number of times that the error signal exceeds the preset voltage may be counted over a preset time period (fig 4A, Ta). The time period for which the error signal exceeds the preset voltage (fig 4B, Tb) can also be counted and, when greater than a threshold value may also enable the control signal. Comparator and over-current protection circuitry 350 may be embedded on a control chip that may also include switching transistor unit 108, the circuit allows over-current protection without using a series resistor (figs 2A, 2B, R) to detect the load current IL. |
