The driving and control device according to the present invention provides
a desired switched current to a load including a string of one or more
electronic devices, and comprises one or more voltage conversion means,
one or more dimming control means, one or more feedback element and one
or more sensing means. The voltage conversion means may be a DC-to-DC
converter for example and based on an input control signal converts the
magnitude of the voltage from the power supply to another magnitude that
is desired at the high side of the load. The dimming control element may
comprise a switch such as a FET, BJT, relay, or any other type of
switching device, for example, and provides control for activation and
deactivation of the load. The feedback means is coupled to the voltage
conversion element and a current sensing element and provides a feedback
signal to the voltage conversion element that is indicative of the
voltage drop across the current sensing element which thus represents the
current flowing through the load. The current sensing element may
comprise a fixed resistor, variable resistor, inductor, or some other
element which has a predictable voltage-current relationship and thus
will provide a measurement of the current flowing through the load based
on a collected voltage signal. Based on the feedback signal received, the
voltage conversion means can subsequently adjust its output voltage such
that a constant switched current is provided to the load.