Led driver circuit

A circuit for operating at least one LED, comprising:

• a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit,
• further comprising a unit for registering the battery-discharge current which is functionally connected to the control unit, wherein for the purpose of regulating the battery-discharge current the current through the LED is adjustable, in a manner depending on the registered battery-discharge current, by adjustment of the switching behavior of the switch of the driver circuit.

A circuit for operating at least one LED, comprising:

• a driver circuit with a coil and with a switch connected in series with the coil and clocked at a high frequency,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit,
• the control unit carrying out a test measurement of electrical parameters at start-up, in order to determine whether an LED or which LED is connected to the driver circuit.

A circuit for operating at least one LED, comprising:

• a driver circuit with a coil and with a switch which is connected in series with the coil and clocked at a high frequency,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal to a control unit,
• the control unit increasing the LED current at start-up, by appropriate triggering of the switch of the driver circuit, from a low value to a stationary operating value.

A process for ascertaining the current through an LED which is operated by a circuit that comprises:

• a coil and a switch connected in series with the coil,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal,
• wherein the temporally averaged value of the current through the LED is ascertained on the basis of the value of the registering signal at the end of the on-time cycle and also on the basis of the value at the end of the demagnetizing phase.

A process for operating an LED with a circuit that comprises:

• a coil and a switch which is connected in series with the coil,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal,
• wherein the LED is operated from a battery,
• wherein the battery-discharge current is registered and for the purpose of regulating the battery-discharge current the current through the LED is adjusted, in a manner depending on the registered battery-discharge current, by adjustment of the switching behavior of the switch of the driver circuit.

A process for operating an LED with a circuit that comprises:

• a coil and a switch which is connected in series with the coil,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal,
• wherein the LED is operated from a battery,
• wherein the battery voltage is registered and the current through the LED is adjusted, in a manner depending on an output signal of the circuit for registering the battery voltage, by adjustment of the switching behavior of the switch of the driver circuit.

A process for operating an LED with a circuit that comprises:

• a coil and a switch which is connected in series with the coil,
• wherein when the switch is closed the coil is magnetized and when the switch is open the coil demagnetized in the form of a current through the LED,
• wherein in the demagnetizing-current path when the switch is open a current-registering means is provided which supplies a current-registering signal,
• wherein the LED voltage is increased at start-up of the circuit, by appropriate triggering of the switch of the driver circuit, from a low value to a stationary operating value.