| 摘要 |
A power supply for point-of-sale (POS) devices. The power supply comprises a transformer with first through fourth windings. An AC input is connected through a backfeed relay to the first winding. An AC output is also connected to the first winding. A battery and an inverter are connected to the second winding. A charger is connected to the third winding. A rectifier, DC/DC regulator and a DC output are connected to the fourth winding. When AC power is received at the AC input, the AC output and the transformer receive the AC power through the backfeed relay. The DC output receives DC power through the DC/DC regulator and the rectifier, which receives AC power through the transformer. When AC power is not received at the AC input, the battery and the inverter provide AC power to the transformer, and the AC output and the rectifier receive AC power from the transformer. The DC output receives DC power through the DC/DC regulator and the rectifier.
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