| 摘要 |
Disclosed is an electrical control circuit (10) for controlling current through a plurality of resistive loads (14(1), 14(2) . . . 14(N)). The control circuit includes a plurality of current control stages (12(1), 12(2), . . . 12(N)), a comparator circuit (18), and a plurality of diodes D1, D2. . . DN-1 in serial connection with the current control stages. The comparator circuit controls the current that is drawn collectively through the loads. The diodes ensure that all preceding current control stages in the series are conducting a predetermined level of current before the next current control stage begins to source current through its respective load. Each current control stage includes an operational amplifier (30), a pass transistor (34), a sense resistor (Rs), and a feedback resistor (Rf). The operational amplifiers are a pre-drive to the pass transistors to allow smaller sense resistors to be used, thereby providing greater efficiency. The feedback resistors (Rf) provide feedback to the operational amplifiers.
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