US 8,659,235 B2 · Process and circuitry for controlling a load

Abstract

A current source and an associated method for supplying current to a load such as an arrangement of LEDs. The intensity of the supplied current varies as a function of the temperature of the load. The intensity of the current is temperature-dependent and limited to a predefined maximum. The temperature dependence is achieved by the component parts that are used without the help of special temperature sensors. The current source is supplied with a reference voltage derived from an integrated circuit. The reference voltage is tapped from a port of the IC and therefore it is switchable. The reference voltage is used to produce a control current, which is fed through a driver stage to produce the current of the current source. Elements in the current source limit the current's intensity and change it as a function of temperature.

Claims20

Dependent claims

A method to supply a load with current from a current source, the method comprising:

generating a reference voltage at an integrated chip;
tapping by the current source the reference voltage from a port of the integrated chip such that the reference voltage is switchable;
generating by the current source a control current as a function of the reference voltage;
feeding by the current source the control current to a driver stage of the current source for the current source to produce a supply current to be supplied from an output of the current source to the load;
and
limiting by the current source the supply current to a pre-defined maximum and changing by the current source the intensity of the supply current as a function of temperature of the load.

3 more elements

A current source with adjustable temperature response to drive a load, the current source comprising:

a reference voltage source having an integrated chip with an output port for outputting a reference voltage;
a current determining unit having a second transistor, a fifth resistor, a sixth resistor, an S-resistor (RS), and a K-resistor (RK), wherein the base of the second transistor is connected with the output port of the integrated chip through the fifth resistor for the current determining unit to tap the reference voltage from the output port of the integrated chip;
a voltage modification unit having a third transistor, a first resistor, a second resistor, a third resistor, and a fourth resistor, wherein the collector of the third transistor is connected to a supply voltage through the first resistor, wherein the fourth resistor is connected in parallel to the emitter of the third transistor and the first resistor, wherein the emitter of the third transistor is connected to the collector of the second transistor;
and
a driver stage having a first transistor and an emitter resistor, wherein the emitter of the first transistor is connected to the supply voltage through the emitter resistor, wherein the base of the first transistor is connected with the emitter of the third transistor and the second resistor.

2 more elements

Dependencies are inferred from the claim text.

Process and circuitry for controlling a load

Life of this patent

Process and circuitry for controlling a load

Life of this patent

Abstract

Claims20