Control circuit and method for a fly-back voltage converter
In a fly-back voltage converter that includes a transformer to transform a primary current to a secondary current and a switch serially coupled to the primary winding to switch the primary current in response to a control signal, a detection signal is produced by comparing the secondary current with two threshold values after the primary current is switched off to trigger the next on-time cycle of the switch. Once the secondary current is detected to be greater than a first threshold value, it is determined that the secondary current has been switched on, and until the secondary current is detected to be lower than a second threshold value, it is determined that the secondary current is to be switched off. The hysteresis range of the threshold values prevents error detection of the secondary current.
Richtek Technology Corp.
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inventional additional additional
Chung-Lung Kwan-Jen Jing-Meng Yuan-Huang
Pai Chu Liu Cheng