Multiple power FET vehicle lamp switch arrangement with charge pump sharing

A vehicle multiple lamp control, the lamps being of the type having a resistance which is low when the filament is cold and increasing with filament temperature, the control comprising, in combination:

• an electric power supply having a supply voltage;
• at least two MOSFETs, each having a pair of current carrying electrodes connected in series between one of the multiple lamps and the power supply, a control electrode responsive to the voltage between the control electrode and one of the current carrying electrodes to control the current flow between the current carrying electrodes and therefore through the corresponding lamp, and a control electrode capacitance;
• a single charge pump powered by the power supply and effective to provide a current flow at a voltage larger than that of the power supply;
• an electrically controlled switch for each MOSFET control electrode for controlling connection of the control electrode to the charge pump;
• first clocked multiplexing switch control means effective to activate each switch to connect the corresponding control electrode to the charge pump in a predetermined order with a first predetermined delay between each two successive activations and further effective to disconnect each control electrode from the charge pump before the following control electrode is connected;
• discharge means for the control electrode capacitance of each MOSFET;
• second clocked multiplexing switch control means effective to activate each switch to connect the corresponding control electrode to the charge pump in a predetermined order with a second predetermined delay between each two successive activations and further effective to activate the discharge means for each MOSFET a third predetermined delay after the switch activation for the MOSFET, the third predetermined delay being longer than the second predetermined delay;
• means responsive, when activated, to the control electrode voltage of each MOSFET to disconnect the control electrode from the charge pump when the control electrode voltage exceeds a first predetermined voltage, the charge pump being effective to raise the control electrode voltage to exceed the first predetermined voltage within the second predetermined delay before the next MOSFET control electrode is connected to the charge pump;
• and
• means responsive to the voltage drop across each lamp to alternatively activate the first clocked multiplexing switch control means, when the voltage drop exceeds a first predetermined reference, and both the second clocked, multiplexing switch control means and the means responsive to the control electrode voltage, when the voltage drop does not exceed the first predetermined reference.