AVERAGE CURRENT CONTROL FOR A SWITCHED POWER CONVERTER

摘要

A circuit for controlling a switch in a power converter in which peak current is regulated to achieve a specified average current through a load. The circuit can include a first input to receive a voltage corresponding to a pre-specified target average current through the load, and a second input to receive a voltage corresponding to a voltage across a sensing resistor immediately after the switch turns ON. The circuit generates a threshold value that is approximately equal to twice the voltage corresponding to the pre-specified target average current through the load, minus the voltage corresponding to a non-zero voltage across the sensing resistor just after the switch turns ON. Control logic is operable to monitor a voltage across the sensing resistor such that when the voltage across the sensing resistor reaches or exceeds the threshold value, the control logic generates a signal that causes the switch to be turned OFF.

主权项

1. A switched power converter in which peak current is regulated to achieve a specified average current through a load, the switched power converter comprising:
a load; a sensing resistor; a switch having a first terminal coupled to the load, a second terminal coupled to the sensing resistor, and a third terminal operable such that a signal applied to the third terminal controls turning ON and OFF of the switch; control logic operable to monitor a voltage across the sensing resistor, wherein when the voltage across the sensing resistor exceeds a threshold value, the control logic generates a signal that causes the switch to be turned OFF, the control logic including a circuit to generate the threshold value based, at least in part, on a pre-specified value corresponding to a target average current through the load, wherein the control logic is operable to generate the signal to cause the switch to be turned OFF so that the average current flowing through the load is about equal to the target average current value.