CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

This patent application claims priority from Chinese Patent Application No. 202010373974.X filed May 6, 2020. This patent application is herein incorporated by reference in its entirety.

TECHNICAL FIELD

The technical field of the present disclosure generally relates to drivers for driving loads. In particular, the present disclosure relates to a driving unit, a driver and an LED (light emitting diode) light source with a driver.

BACKGROUND

Drivers for providing an output current for driving loads are known. Further, drivers with adjustable output current are also known, such that the driver current can be set by means of external elements, such as resistors, jumpers or switches. Such drivers, however, provide only a limited selection for the output current value, while drivers with wider options for the output current settings are relatively complex, error-prone and expensive.

SUMMARY

An object of the present application is to provide a driver unit for programming an output current of a driver which is particularly robust and inexpensive.

According to a first aspect, a driver unit for programming an output current of a driver with an output stage for providing the output current and a primary control stage with a control input for controlling the output current is provided. The driver unit comprises a programmable, in particular, electrically programmable memory unit for storing data corresponding to or representing a target value or target level of the output current. The driver unit further comprises a programing signal circuit configured to provide electric signals for writing the data in the programmable memory unit and a controller circuit with a controller, or micro-controller unit operatively connected to the programmable memory unit. The controller is configured to read out the data stored in the programmable memory unit and generate a controller output signal for adjusting the output current of the driver, based on the data stored in the programmable memory unit. In particular, based on the controller output signal, a control signal for feeding in the primary control stage of the driver can be provided, such that a control loop for adjusting the output current of the driver in accordance with the data stored in the programmable memory unit can be formed.

By feeding in the control signal in the control input of the primary control stage of the driver, the driver output current can be easily set in accordance with the data stored in the programmable memory unit. Thus, the driving unit can be used for providing a programmable driver which allows to set and regulate the output current at a desired level.

The programming signal circuit may comprise a terminal connectable to the output stage of the driver or driver bus. Further, the programming signal circuit may be configured such that the electric signals for writing the data in the programmable memory unit are disableable by applying a voltage at the terminal, in particular, relative to a ground potential.

The terminal of the programming signal circuit may be connected with the output stage of the driver in such a way that when the driver is in operation, there is an electric potential at the terminal, disabling the electric signals for writing the data in the programmable memory unit. Thus, the process of programming of such a driver is only possible when the driver is “off-line” or switched off. This off-line programming feature makes the driver particularly convenient and safe for the user, since for programming such a driver, the driver must be switched off, and the user has no reason to contact the driver for programming, as long as the driver is in operation.

The programming signal circuit may comprise an enabling switch for enabling the electric signals for writing the data in the programmable memory unit. In particular, the programming signal circuit may comprise an output circuit, and the enabling switch may be configured such that closing the enabling switch closes the output circuit. Hence, in order to program the programmable memory unit, the enabling switch, which is otherwise open, must be closed. Thus, in the normal state, when the programmable memory unit is not being programmed, the output circuit is open, and the programming signal circuit is disabled. Consequently, the programming signal circuit consumes particularly low power. Besides, any unintentional writing or erasing of data in the memory by an erroneous signal can be avoided.

The programming signal circuit may further comprise a disabling switch for disabling the electric signals for writing the data in the programmable memory unit, in particular, by opening the enabling switch, when a voltage at the terminal is applied. Therefore, irrespective whether the driver is in operation or not, the programming signal circuit is always disabled, unless the programming signal circuit is used for programming the programmable memory unit. Thus, the power consumption of the programming signal circuit can be reduced.

In some embodiments, the enabling switch and the disabling switch may be transistor switches based on MOSFETs (metal-oxide-semiconductor field-effect transistor), each of the MOSFETs comprising a source, a drain and a gate, wherein the gate of the enabling switch is connected with the drain of the disabling switch and the gate of the disabling switch is electrically connected to the terminal of the programming signal circuit. MOSFETs are suitable switches because of their robustness and low power consumption.

The programmable memory unit may comprise a single-wire programmable memory device. For programming a single-wire programmable memory device, one electric line is required. Hence, any complex interface for programming the programmable memory unit can be avoided. In particular, any wireless interface, e.g. based on an NFC (near field communication), BLE® (Bluetooth Low Energy), or WiFi® protocol, can be avoided. Moreover, the wireless interfaces require antennas which are unsuitable for metal housing applications, cause additional costs for waterproof design and standby power loss during programming. Moreover, for programming communication between programming device and the programmable memory unit, a connection wire connecting the output stage of the driver to the load can be used. Thus, the single-wire programmable memory unit allows to keep the circuitry of the programmable driver simple and compact.

The programmable memory unit may comprise an EEPROM (electrically erasable programmable read-only memory), in particular a one-wire-programmable EEPROM, which is an easily available low-cost commodity component.

The output circuit of the programming signal circuit may comprise an inductive element configured to inductively couple the electric signals for writing the data to the programmable memory unit. The inductive coupling between the programming signal circuit and the programmable memory unit can serve as a low-pass filter or surge arrester for suppressing interference signals.

The controller circuit may be operatively connectable to the output stage of the driver, such that the data communication between the controller and the programmable memory unit is disabled when the driver is off. In particular, the controller may comprise a terminal connectable with the output stage of the driver, and the controller may be configured such that the data communication between the controller and the programmable memory unit is disableable by applying a voltage on the terminal. By disabling the data exchange between the programmable memory unit and the controller, power dissipation, in particular, caused by the data communication between the programmable memory unit and the controller, in a stand-by regime, can be avoided.

The driver unit may comprise an output section connectable to the output stage of the driver and configured to form the control signal based on the controller output signal and a current value of the output current. In particular, the output section of the driver unit can be configured such that the output signal is formed in accordance or suitable to the control input of the driver.

The output stage may comprise an error amplifier or differential amplifier with a first input connectable to the output stage of the driver for sampling the output current and a second input electrically connected to the controller output for providing a reference for the error amplifier. The output signal of the error amplifier reflects the difference between the current value of the output current and the target level of the output current. The differential signal at the output of the error amplifier can be used for keeping the output current of the driver essentially at the target level.

In some embodiments, the controller is configured such that the controller output signal is a PWM (pulse-width modulation) signal with a duty cycle depending on the data stored in the programmable memory unit. Controllers or microcontroller units providing a PWM signal with variable duty cycles are easily available low-cost commodity components.

The driver unit may comprise a controller output circuit with an RC filter for providing a DC (direct current) reference voltage for the error amplifier. In particular, the RC filter filters the controller output signal such that the reference voltage level at the second input of the error amplifier reflects the characteristics, in particular the duty cycle, of the controller output signal, and hence the data stored in the memory unit. Thus, when a voltage reflecting the current value of the output current is applied at the first input of the error amplifier, the error amplifier can provide a correction signal as an input for the control input of the driver, adjusting the output current at the target level. Hence an analog controlling for adjusting the output current, in particular, without PWM flickering, can be achieved.

According to another aspect a driver comprising a driver output stage or driver bus for providing an output current, a primary control stage with a control input for controlling the output current and a driver unit according to the first aspect for programming the output current of the driver is provided. The output stage of the driver unit is connected to the control input of the driver such that the output current is adjustable essentially at the target level, based on the data stored in the programmable memory unit of the driver unit. The driver is particularly reliable, inexpensive, and easy to program.

The programming signal circuit of the driver unit may be connected to the output stage of the driver, such that the programming signal circuit is disabled when the driver is on. By disabling the programming signal circuit, the programming of the driver is not possible when the driver is on. Thus, such a driver is also safe for the user.

According to a third aspect an LED light source is provided. The LED light source comprises at least one LED for generating light and a driver according to the above aspect, connected to the at least one LED such that the at least one LED can be driven by the driver. Due to the programmable output current of the driver, the current flowing through the at least one LED and hence the light output of the light source can be easily programmed by the user. Besides, such a programmable light source is particularly inexpensive and safe for the user.

