| 摘要 |
<p>A switching power supply is provided in two stages with the primary of the power transformer (18) being in the first stage and the secondary in the second stage. The first stage (Stage 1) includes an EMI filter (12) connected to the input of a rectifier (14). The output of the rectifier is connected to a self oscillating, half-bridge, resonant inverter (16) operating in open loop with the primary of the transformer (18) to provide isolation from the power source (10). Feed-forward control is used to compensate for line variations, providing very small output voltage variation compared with input voltage variation. In the second stage (Stage 2), the secondary of the transformer (18) provides an input to post regulator circuitry (20) including a PWM control circuit (34) to regulate the output current using the error signal representing the differences between the current sensed and the desired value.</p> |
