| 摘要 |
A low cost load sensing technique that is suitable for use in sensing batteries in a battery charging circuit is disclosed. The circuit is adapted to be utilized in conjunction with a power supply which may include a primary converter and a voltage feedback circuit. A transformer with a dual secondary winding is connected between the primary converter and the output terminals of the charging circuit. When no load or battery is present, a first feedback loop is utilized with both of the secondary transformer windings in series, which supplies a constant output voltage at the output terminals. When a load is present, a second feedback loop is utilized which includes one of the secondary windings to provide the voltage of the output terminals. A capacitor is connected in parallel with the other secondary winding. When a load is present, a step increase in voltage occurs across the capacitor due to the fact that the both secondary windings are in phase when a load is present. The voltage across the capacitor is used to drive an indicating circuit which provides an indication of a battery when the voltage across the capacitor exceeds a predetermined value. The indicating circuit may include a voltage divider and a Zener diode, configured to drive a transistor. The configuration of the indicating circuit as well as the feedback loops enable the circuit to detect a load, such as a battery, over a relatively wide dynamic range.
|
