CONVERSION UNIT

A conversion unit for decreasing an input voltage into an output voltage. The conversion unit includes a step-down converter circuit with at least two voltage inputs for the input voltage, at least two control units, wherein each control unit is assigned to a voltage input, wherein each control unit is configured, upon receipt of a time signal, to output a switch signal to apply the input voltage to the assigned voltage input, and, upon receipt of a reset signal, to reset the switch signal, to receive the switch signal of another control unit, and, upon receipt, to reset a permission signal, to output the switch signal only if the permission signal is reset, and to provide the permission signal when the switch signal is output.

CROSS REFERENCE

The present application claims the benefit under 35 U.S.C. § 119 of German Patent Application No. DE 10 2023 203 899.4 filed on Apr. 27, 2023, which is expressly incorporated herein by reference in its entirety.

FIELD

The present invention relates to a conversion unit for decreasing an input voltage into an output voltage. The conversion unit is preferably designed to be multi-phase.

BACKGROUND INFORMATION

Conversion units are described in the related art. An exemplary conversion unit1with two phases is shown inFIG.1. The conversion unit1comprises a step-down converter circuit2, which is designed to be two-phase, wherein each phase is provided for converting an input voltage VIN into an output voltage VOUT. Thus, a first voltage input4aand a second voltage input4bare present. A respective control unit3a,3bis assigned to each voltage input4a,4b. The control units3a,3bare D flip-flops, which output a switch signal ON1, ON2on the basis of a time signal CLK1, CLK2. The switch signal ON1, ON2controls an input switch unit5a,5b, by means of which the respective input voltage VIN is applicable to the voltage input4a,4b. The inversion of the switch signal ON1, ON2controls a reference switch6a,6b, by means of which a reference voltage, in particular a ground, is applicable to the voltage input4a,4b.

Per phase, the step-down converter circuit2has an inductance L1, L2as well as a capacitance COUTin order to carry out the step-down conversion. The output voltage VOUTis applicable to a load, represented here by the resistance RLOAD.

Each control unit3a,3bcan be reset by means of a respective reset signal RESET1, RESET2. The reset signals RESET1, RESET2are generated by a respective PWM comparator15a,15b, wherein the inputs of the PWM comparator15a,15bare formed by an error amplifier output VEAMP of an error amplifier gmand by an output VCSX1, VCSX2. Depending on the switch signal ON1, ON2, the output VCSX1, VCSX2is either a reset voltage VRESETor the output of a current measurement by means of a shunt resistor RSHUNT1, RSHUNT2of the output current. The error amplifier gmhas the output voltage VOUTas well as a reference voltage VREFas inputs.

With very short switch-on times of the phases, which each start with a rising edge of the respective time signal CLK1, CLK2and end with RESET1=high or RESET2=high, the switching-on of the phases can be prevented at any point in time by regulating the error amplifier output VEAMP to below a VRESETthreshold. Such short switch-on times usually occur during a soft start, i.e., the target value of the output voltage is ramped up slowly. However, even after reaching the target value, the switch-on time can be shorter than a technically specified minimum switch-on time.

As a result of beats in the time curve of the VEAMP, an imbalance can arise, in the case of which only one or no longer all phases present is/are being switched on. In the phases that are no longer switched on, the coil current can drop sharply into the negative range as a result, which must be compensated by the still active phases with increased positive coil current. This leads to a reduction in the electrical power efficiency overall. Furthermore, additional unforeseeable frequency components occur, which differ from the specification by CLK1, CLK2and may pose a problem with regard to electromagnetic compatibility.

SUMMARY

The conversion unit according to the present invention allows for reliable switching of all phases. In particular, a negative coil current is prevented from arising due to a switching of phases being skipped. Rather, it is achieved that all phases are switched in a specified order. This increases electrical power efficiency.

According to an example embodiment of the present invention, the conversion unit for decreasing an input voltage into an output voltage comprises a step-down converter circuit and at least two control units. The step-down converter circuit comprises at least two voltage inputs for the input voltage. A control unit is assigned to each voltage input. The step-down converter circuit is thus multi-phase, wherein a phase of the step-down converter circuit is controllable by a respective control unit.

Each control unit is configured to output a switch signal upon receipt of a time signal. The switch signal achieves that the input voltage is applied to the assigned voltage input. Furthermore, each control unit is designed to reset the switch signal upon receipt of a reset signal. This represents the usual functionality that conventional control units carry out. Additionally, each control unit is designed to receive the switch signal of another control unit and, upon receipt, to reset a permission signal. The other control unit from which the switch signal is received is such a control unit that controls a preceding phase. Coupling the control units in this way achieves that the control units can switch only in a specified order. For this purpose, each control unit is designed to output the switch signal only if the permission signal is reset, and to provide the permission signal when the switch signal is output.

If a preceding phase is not switched, for example due to the aforementioned problems, the switch signal is not set and, as a result, the permission signal for the subsequent phase is also not reset. In other words, the control unit of the subsequent phase cannot receive the switch signal, as a result of which the subsequent phase is also not switched. The specified order is thus reliably maintainable.

Preferred developments and example embodiments of the present invention are disclosed herein.

Preferably, according to an example embodiment of the present invention, each control unit is designed to use the switch signal to cause an input switch unit to apply the input voltage to the assigned voltage input. The input switch unit is a transistor, for example. Preferably, the input switch unit is part of the step-down converter circuit. In particular, the switch signal is used to switch the input switch unit to a conductive state in order to apply the input voltage to the voltage input.

Preferably, according to an example embodiment of the present invention, each control unit is designed to use the inverted switch signal to cause a reference switch unit to apply a reference voltage to the assigned voltage input. The reference switch unit is a transistor, for example. Preferably, the reference switch unit is part of the step-down converter circuit. In particular, the inverted switch signal is used to switch the reference switch unit to a conductive state in order to apply the reference voltage to the voltage input. The reference voltage is in particular ground. Using the inverted switch signal ensures that the reference voltage is applied whenever the corresponding phase is not to be switched, which is represented by the reset switch signal. If the switch signal is reset, the inverted switch signal becomes logical 1.

Preferably, according to an example embodiment of the present invention, each control unit comprises a first D flip-flop and a second D flip-flop. It is provided that the first D flip-flop is designed to output the switch signal upon receipt of the time signal at a dynamic input. The second D flip-flop is designed to provide the permission signal upon receipt of the switch signal and to reset the permission signal upon receipt of the switch signal from another control unit. The first D flip-flop is thus used for handling the time signal and the corresponding response thereto. The second D flip-flop is used for handling the permission signal. The provision of the switch signal by the first D flip-flop can thus be prevented by the second D flip-flop even if the time signal provides for the provision of the switch signal. The second D flip-flop thus makes it possible to maintain the specified order of the switching of the phases.

Particularly preferably, according to an example embodiment of the present invention, the first D flip-flop comprises a reset input to which a resetting signal is outputtable. The resetting signal is provided by an OR gate, wherein the reset signal and an output of a NOR gate are transmittable as inputs to the OR gate. The first D flip-flop can thus be reset by the reset signal, as already possible in the related art. Additionally, the OR gate makes it possible to incorporate a further logic, which is present as a result of the NOR gate and the second D flip-flop. This further logic is based on the permission signal and has the goal of maintaining the provided order of the switching of the phases. The switch signal and the inverted permission signal are transmittable as inputs to the NOR gate. If the permission signal is present and the switch signal is reset, the output of the NOR gate is logical 1. The first D flip-flop thus remains reset. This state is only canceled by resetting the permission signal. Since this takes place by the switch signal of the preceding phase, it is ensured that the specified switching order of the phases is maintained.

Preferably, according to an example embodiment of the present invention, the second D flip-flop comprises a reset input. The switch signal of the other control unit is applicable to the reset input. The reset input of the second D flip-flop is thus connected to the output of the first D flip-flop of the other control unit. A connection between the control units is therefore provided in order to reset the permission signal for the subsequent phase at the same time as the switch signal is output.

According to an example embodiment of the present invention, the control unit is preferably designed to apply the switch signal to a dynamic input of the second D flip-flop. The provision of the permission signal thus takes place when the switch signal is present. In other words, the permission signal is always provided at the same time as the switch signal. Outputting a switch signal again is thus prevented until the permission signal is reset.

According to an example embodiment of the present invention, it is particularly advantageously provided for respective data inputs of the first D flip-flop and/or of the second D flip-flop to be logical 1. This logical 1 is thus also adopted at the respective output if this is specified by the dynamic input of the respective D flip-flop. This in particular makes it possible for the first D flip-flop to output the switch signal when the time signal is present, and for the second D flip-flop to output the permission signal when the switch signal is present. This can only be prevented by the corresponding reset inputs.

According to an example embodiment of the present invention, preferably, a buffer is arranged between the second D flip-flop and the first D flip-flop. The buffer delays the transmission of the switch signal to the second D flip-flop. This avoids unstable behavior of the conversion unit.

The present invention also relates to an integrated circuit. The integrated circuit comprises a conversion unit as described above. In particular, the integrated circuit is used to control driver assistance systems of vehicles.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG.2schematically shows a conversion unit1according to an exemplary embodiment of the present invention. In this example, a two-phase conversion unit1is shown. The conversion unit1differs from the conventional two-phase conversion unit shown inFIG.1only by the respective control units3a,3bof the voltage inputs4a,4bof the conversion unit. In particular, the multi-phase step-down converter circuit2is unchanged.

Each control unit3a,3bis configured to output a switch signal ON1, ON2upon receipt of a time signal CLK1, CLK2in order to apply the input voltage VIN to the assigned voltage input4a,4b, and to reset the switch signal ON1, ON2upon receipt of a reset signal RESET1, RESET2. At this point, the respective control unit3a,3bdoes not differ from the related art. Additionally, each control unit3a,3bis designed to receive the switch signal ON1, ON2of the respective other control unit and, upon receipt, to reset a permission signal M1, M2. Each control unit3a,3boutputs the switch signal ON1, ON2only if the permission signal M1, M2is reset. In addition, each control unit3a,3balso provides the permission signal M1, M2when the switch signal ON1, ON2is output. The permission signal M1, M2is only used within the respective control unit and is not output.

Through this design, it is achieved that a switch signal ON1, ON2is output only if the switch signal ON1, ON2of the other control unit3a,3bhas previously been received. In other words, it is ensured that a first switch signal ON1of a first control unit3aand a second switch signal ON2of a second control unit3bare always output alternately. If one of the switch signals ON1, ON2is skipped due to a problem described above, the permission signal M1, M2ensures that the other phase is also not switched. In this way, a drop in the coil current into the negative can in particular be avoided.

This principle can be extended to more than two phases. In this case, it must always be ensured that a control unit3a,3breceives the switch signal ON1, ON2of the other control unit3a,3bthat controls the preceding phase. In this way, an order is defined in which the individual phases are to be switched. If a phase is skipped, the control units3a,3bensure that all other phases are also skipped until the causally skipped phase is to be switched again due to the respective time signal CLK1, CLK2.

Each control unit3a,3bcomprises a first D flip-flop7a,7band a second D flip-flop8a,8b. The first D flip-flop7a,7bis designed to receive the time signal CLK1, CLK2at a dynamic input. If the time signal is received, the first D flip-flop7a,7bis used to provide the switch signal ON1at an output.

The first D flip-flop7a,7balso comprises a reset input9a,9bto which a resetting signal R1, R2is outputtable. In contrast to the related art, this resetting signal R1, R2is not the reset signal RESET1, RESET2but is generated by additional logic. The resetting signal R1, R2is provided by an OR gate10a,10b, wherein the reset signal RESET1, RESET2and an output of a NOR gate11a,11bare transmittable as inputs to the OR gate10a,10. The switch signal ON1, ON2and the inverted permission signal M1, M2are transmittable as inputs to the NOR gate11a,11b. Due to the OR gate10a,10b, resetting the first D flip-flop7a,7bby means of the reset signal RESET1, RESET2is possible, as in the related art. Additionally, the permission signal M1, M2provides an extended logic, which makes possible the alternating switching of the phases described above.

A second D flip-flop8a,8bis provided for handling the permission signal M1, M2. The second D flip-flop8a,8bis designed to provide the permission signal M1, M2upon receipt of the switch signal ON1, ON2and to reset the permission signal M1, M2upon receipt of the switch signal ON1, ON2from the other control unit3a,3b. Each control unit3a,3bis therefore designed to apply their (own) switch signal ON1, ON2to a dynamic input of the second D flip-flop8a,8band the switch signal ON1, ON2of the other control unit3a,3bto a reset input12a,12bof the second D flip-flop8a,8b. Logical 1 is permanently applied to the respective data inputs of the first D flip-flop7a,7band/or of the second D flip-flop8a,8b.

Preferably, a buffer13a,13bis arranged between the dynamic input of the second D flip-flop8a,8band the output of the first D flip-flop7a,7bin order to transmit the switch signal ON1, ON2to the second D flip-flop7a,7bin a delayed manner. This reduces a risk of unstable behavior of the conversion unit1.

The resulting functionality of the control units is shown schematically inFIG.3.FIG.3schematically shows a representation of various signals during operation of the conversion unit1according to the exemplary embodiment of the present invention, wherein a third phase is present for better understanding. This means that the conversion unit1comprises three control units3a,3band three voltage inputs4a,4bas described above.

FIG.3shows the respective time signals CLK1, CLK2and CLK3in a first row. They are used to give a switching command to the individual phases of the step-down converter circuit2. The switching of the phases is carried out by the respectively assigned control unit3a,3bby means of the switch signal ON1, ON2, ON3. It is provided that the phases are to be switched sequentially in ascending numbering, i.e., first the first phase, then the second phase, then the third phase, and then again restarting with the first phase.

In a second row,FIG.3shows the relevant signals of the first control unit3a, the relevant signals of the second control unit3bin a second row, and the relevant signals of a third control unit (not shown) in a third row. The relevant signals are the switch signal ON1, ON2, ON3, the permission signal M1, M2, M3, the reset signal RESET1, RESET2, RESET3, and the resetting signal R1, R2, R3.

Initially, all permission signals M1, M2, M3are reset. If the first time signal CLK1is present, i.e., the corresponding curve inFIG.3shows logical 1, the D flip-flop7aof the first control unit3aprovides the first switch signal ON1, and switching takes place by step-down converter circuit2, in particular the first input switch unit5aand the first reference switch unit6a. At the same time, due to the second D flip-flop8aof the first control unit3a, the switch signal ON1is received and, as a result, the first permission signal M1is provided, which is shown by the rising edge inFIG.3. The first reset signal RESET1received by the step-down converter circuit2resets the first switch signal ON1since, due to the first OR gate10a, the first reset signal RESET1causes the first resetting signal R1, which is applied to the reset input9aof the first D flip-flop7aof the first control unit3a.

As a result of resetting the first switch signal ON1, the first switch signal is no longer applied to the input of the first NOR gate11a. Furthermore, the inverted first permission signal M1is applied to the input of the first NOR gate11a, whereby the inputs of the first NOR gate11aare each logical 0 so that an output of the first NOR gate11ais logical 1. Due to the first OR gate10a, the first resetting signal R1is thus always provided, even if the first reset signal RESET1is reset again. As a result, logical 1 is applied to the reset input9aof the first D flip-flop7aof the first control unit3a, and outputting of the first switch signal ON1is prevented independently of the first time signal CLK1.

The first phase is to always be switched after the third phase. Therefore, the third switch signal ON3is applicable to a reset input12aof the second D flip-flop8aof the first switch unit3a. As shown inFIG.3, when the third switch signal ON3is present, the first permission signal M1is reset. The first resetting signal R1is thus equal to the first reset signal RESET1.

It is shown inFIG.3that the first switch signal ON1is output as soon as the first time signal CLK1is present on one hand and the first reset signal RESET1, and thus the first resetting signal R1, is reset on the other hand. Through the first switch signal ON1, the first permission signal M1is simultaneously also provided again, and the process described above is repeated.

The same principle also applies to the other phases. As shown inFIG.3, the first switch signal ON1causes a reset of the second permission signal M2. Likewise, the second switch signal ON2causes a reset of the third permission signal M3. In this case, the functional principles of the control units3a,3bare identical; only the corresponding switch signal ON1, ON2, ON3of the preceding phase is to be applied to the reset input12a,12bof the second D flip-flop8a,8bof the respective switch unit3a,3b. If the switching of a phase is skipped, no switch signal ON1, ON2, ON3is output, and the permission signal M1, M2, M3for the subsequent phases is thus also not reset. Switching of the subsequent phases is thus also prevented until the originally skipped phase is first switched again. The specified order for switching the phases is thus reliably maintained.

FIG.4schematically shows an integrated circuit14according to an exemplary embodiment of the present invention. The integrated circuit14is in particular used to control driver assistance systems of vehicles and comprises a conversion unit1according to the exemplary embodiment of the present invention.