Switch mode power supply module having a hiccup mode and item of equipment powered by said module

Abstract

The invention relates to switch mode power supply modules and items of equipment powered by these modules. The power supply module comprises circuits for cyclically interrupting the switching operation, during a so-called switching operation interruption phase, if the load current of the module is less than a current threshold value and sustaining the switching operation, during a so-called switching operation phase, if the load current is greater than the load current threshold value and circuits for ending the switching operation interruption phase if the power supply voltage of the item of equipment is greater than a voltage threshold value. The item of equipment powered by the module comprises a capacitive element able to store energy from the module during the switching operation phase and to release the energy stored between the output terminals of the power supply module when it receives an activation signal.

Claims

1. Device comprising an item of equipment; a switch mode power supply module intended to supply power to said item of equipment and comprising a circuit for measuring a power supply voltage present between power supply rails, wherein: said item of equipment comprises a capacitive element connected between power supply rails and an activation circuit, said capacitive element is suitable for storing energy during a switching operation phase of the switch mode power supply module and for supplying the stored energy to said activation circuit during a switching operation interruption phase of the switch mode power supply module; said activation circuit is suitable for applying between said power supply rails the voltage present at the terminals of the capacitive element when said item of equipment is started or woken up by an activation signal, and said switch mode power supply module is suitable for ending the switching operation interruption phase as a function of the measured power supply voltage.

2. The device according to claim 1, wherein said switching operation phase has a first duration.

3. The device according to claim 1, wherein said switching operation interruption phase has a second duration.

4. The device according to claim 1, wherein said switch mode power supply module comprises a switching operation control circuit that cyclically interrupts the switching operation, during said switching operation interruption phase, and sustains the switching operation, during said switching operation, as a function of a load current flowing in said item of equipment.

5. The device according to claim 4, wherein said switching operation control circuit interrupts the switching operation when said load current is less than or equal to a load current value.

6. The device according to claim 4, wherein said switching operation control circuit sustains the switching operation when said load current is greater than a load current value.

7. The device according to claim 1, wherein said item of equipment comprises a voltage converter able to convert the voltage at the terminals of said capacitive element into a lower constant voltage supplying power to the activation circuit.

8. The device according to claim 1, wherein said item of equipment further comprises an activation input suitable for receiving said activation signal.

9. The device according to claim 1, wherein said activation signal comes from a timer.

10. Method for controlling a switching operation, to be performed in a device comprising an item of equipment; a switch mode power supply module intended to supply power to said item of equipment, said method comprising a measuring by said switch mode power supply module of a voltage between power supply rails, wherein said method comprises, in said item of equipment: storing energy in a capacitive element during a switching operation phase of the switch mode power supply module; supplying the stored energy during a switching operation interruption phase of the switch mode power supply module; applying, between said power supply rails, a voltage present at the terminals of said capacitive element when the item of equipment is started or woken up by an activation signal; and that it comprises a stopping by said switch mode power supply module of the switching operation interruption as a function of the measured voltage.

11. The method according to claim 10, wherein said switching operation phase has a first duration.

12. The method according to claim 10, wherein said switching operation interruption phase has a second duration.

13. The method according to claim 10, wherein said method further comprises, in said switch mode power supply module, cyclically interrupting the switching operation, during said switching operation interruption phase, and sustaining the switching operation, during said switching operation, as a function of a load current flowing in said item of equipment.

14. The method according to claim 13, wherein the switching operation is interrupted when said load current is less than or equal to a load current value.

15. The method according to claim 14, wherein the switching operation is sustained when said load current is greater than the load current value.

16. The method according to claim 10, wherein said method further comprises converting, by said item of equipment, the voltage at the terminals of said capacitive element into a lower constant voltage supplying power to an activation circuit.

17. The method according to claim 10, wherein said method further comprises receiving, by said item of equipment, said activation signal.

18. The method according to claim 10, wherein said activation signal comes from a timer.

19. An item of equipment comprising a capacitive element connected between power supply rails and an activation circuit, said capacitive element being suitable for storing energy during a switching operation phase of a switch mode power supply module intended to supply power to said item of equipment, and for supplying the stored energy to said activation circuit during a switching operation interruption phase of the switch mode power supply module, said activation circuit being suitable for applying between said power supply rails a voltage present at the terminals of the capacitive element when said item of equipment is started or woken up by an activation signal.

20. The item of equipment of claim 19 wherein said switch mode power supply is suitable for ending the switching operation interruption phase as a function of a power supply voltage present between power supply rails.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other advantages may also occur to those skilled in the art upon reading the examples below, illustrated by the annexed figures, given by way of illustration:

(2) FIG. 1 shows the diagram of a switch mode power supply module and an item of equipment in accordance with the invention;

(3) FIG. 2 shows the steps of the method for controlling the switch mode power supply module of FIG. 1; and

(4) FIG. 3 shows the steps of the method for controlling the item of equipment of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows an item of electrical or electronic equipment 2 powered by a switch mode power supply module 1, the two devices being in accordance with the invention.

(6) The switch mode power supply module 1 is connected on one hand to the electrical network, also called mains, and on the other hand to the item of equipment 2 via a power cord 3 with two conducting wires. The switch mode power supply module transforms the AC voltage supplied by the mains into a voltage useful for the proper operation of the item of equipment.

(7) According to the invention, the switch mode power supply module 1 comprises, in addition to the standard switching operation means 10, additional switching operation control means for implementing and managing a hiccup mode. During this hiccup mode, the power supply module detects the absence of load and interrupts then reactivates the switching operation of the power supply cyclically to limit the residual consumption of the module. This hiccup mode is interrupted when the item of equipment requires voltage.

(8) According to the invention, the switching operation control means comprises a load current measurement circuit 11, a circuit for comparing 12 said measured load current with a predefined load current threshold value Iref supplied by a current reference circuit 13, and a switching operation control circuit 14 cyclically interrupting the switching operation, during a so-called switching operation interruption phase of predetermined duration, if said measured load current is less than or equal to Iref and sustaining the switching operation, during a so-called switching operation phase of predetermined duration, if the measured load current is greater than Iref.

(9) The load current measurement is carried out during the switching operation phase of the module. In the case of a cycle having a duration of 30 seconds, the duration of the switching operation phase is for example 0.5 seconds and that of the switching operation interruption phase is 29.5 seconds. The load current measurement being carried out by the switch mode power supply module, this latter operates autonomously. The item of equipment does not require to transmit control messages or signals to the item of equipment to move from a so-called normal operating mode, wherein the switching operation is never interrupted, to hiccup mode or vice versa.

(10) The power supply module also comprises a voltage measurement circuit 15 for measuring the power supply voltage present between the two conductors of the power supply cable 3. These two conductors are connected to two power supply rails 20a and 20b of the item of equipment 2. It also comprises a circuit for comparing 16 the measured power supply voltage with a predefined power supply voltage threshold value Uref supplied by a voltage reference circuit 17. When the switching operation control circuit 14 detects that measured power supply voltage is greater than or equal to Uref, it stops the switching operation interruption phase.

(11) In the proposed embodiment, the output of the current comparator 12 and the output of the voltage comparator 16 are connected to the switching operation control circuit 14 via an RS flip-flop 18. The output of the current comparator 12 is connected to input S (for Set) of the flip-flop, the output of the voltage comparator 16 is connected to input R (for Reset) of the flip-flop and output Q of the flip-flop is connected to the input of the switching operation control circuit 14. Thus, if the measured load current exceeds Iref, the flip-flop activates the control circuit 14 in order to implement the hiccup mode and, if the measured voltage exceeds Uref, the flip-flop deactivates the control circuit 14 in order to end the hiccup mode.

(12) As indicated above, hiccup mode is interrupted when the voltage between the power supply rails 20a and 20b of the item of equipment exceeds a power supply voltage threshold value. The item of equipment 2 is therefore modified in order to increase the voltage between the two power supply rails when it requires the switch mode power supply module to exit hiccup mode.

(13) For this purpose, the item of equipment 2 comprises a capacitive element 21 connected between the two power supply rails for storing energy from the switch mode power supply module during the switching operation phase of the switch mode power supply module and to supply the stored energy to an activation circuit 22 during the switching operation interruption phase of the switch mode power supply module. The activation circuit 22 is supplied with power by the capacitive element 21 via a DC converter 23. This voltage converter is intended to convert the voltage at the terminals of the capacitive element, for example of the order of 12 volts, into a lower constant voltage, for example of the order of 3.3 volts. The activation circuit 22 is a low-consumption microcontroller, for example the microcontroller PD789881 manufactured by the company NEC which only consumes 18 microamperes. It is supplied with power between its two terminals VDD and VSS by the voltage delivered by the converter 23. The voltage converter can be a DC/DC converter of buck or step-down type from the TPS54x26/27 series manufactured by the company Texas Instruments which has a PFM mode (Pulse Frequency Mode) for ensuring minimal low-load losses or a linear regulator for example from the LK112xx series manufactured by the company STMicroelectronics or a combination of the two types to optimise performance both in standby mode and in normal mode.

(14) Finally, the capacitive element 21 is a reservoir capacitor having a high value, for example twice the value of the capacitors mounted directly between the power supply rails, capacitors of the switch mode power supply included, that is for example 4700 F if the switch mode power supply has 2000 F. It is connected to power supply rail 20a via a non-return diode 24.

(15) The activation circuit 22 comprises an activation input int at which it receives an activation signal C1 and two outputs out1 and out2 at which it delivers two control signals, respectively C2 and C3.

(16) The activation signal C1 is in an ON state when the item of equipment must be started or woken up. This signal can come from a remote control, a timer or the like.

(17) As soon as the activation circuit 22 receives an ON state activation signal, it delivers an ON state control signal C2 which will control the rapid discharge of the capacitive element 21 into the power supply rails 20a and 20b. This discharge will increase the voltage between the power supply rails and initiate the cessation of hiccup mode.

(18) In the example of FIG. 1, the discharge of the capacitive element 21 is controlled via the intermediary of a transistor-based switch, itself controlled by control signal C2. In FIG. 1, the switch is formed of two transistors T25, T26 and two resistors R25, R26. Transistor T25 is a bipolar transistor and transistor T26 is a field effect transistor of MOS (or MOSFET) type. The base of transistor T25 is connected to output out1 via current limiting resistor R25, its emitter is connected to power supply rail 20b and its collector is connected to the gate of transistor T26. The gate and the source of transistor T26 are connected to each other by resistor R26. Finally, the drain of transistor T26 is connected to power supply rail 20a and its source is connected to the cathode of the capacitor 21.

(19) Thus, when the item of equipment receives an ON state activation signal C1, said activation circuit 22 controls the connection of the capacitive element 21 between the rails 20a and 20b. The voltage between the two rails then increases suddenly. This increase in voltage is detected by the voltage comparator 16 which ends hiccup mode.

(20) In order to avoid the energy stored by the capacitive element 21 being absorbed by the load of the item of equipment during the sudden discharge of the capacitive element, the item of equipment is advantageously supplemented by a second switch. In FIG. 1, this second switch is formed of two transistors T27, T28 and two resistors R27, R28. Transistor T27 is a bipolar transistor and transistor T28 is a field effect transistor of MOS (or MOSFET) type. The base of transistor T27 is connected to output out2 via current limiting resistor R27, its emitter is connected to power supply rail 20b and its collector is connected to the gate of transistor T28. Transistor T28 is arranged on power supply rail 20a, the source of transistor T28 being connected to an upstream part of rail 20a and the drain of transistor T28 being connected to a downstream part of rail 20a. The upstream part of rail 20a supplies power to the capacitive element 21 and the converter 23. The downstream part of rail 20a supplies power to the remainder of the item of equipment. The gate and the source of transistor T28 are moreover connected to each other by resistor R28.

(21) According to the invention, the activation circuit 22 delivers an ON state control signal C3 after delivering ON state control signal C2. Thus, when control signal C2 is in ON state, the capacitive element does not discharge into the upstream part of the item of equipment.

(22) The operation of the switch mode power supply module 1 and of the item of equipment 2 is shown by, respectively, FIG. 2 and FIG. 3.

(23) In reference to FIG. 2, the method for controlling the switch mode power supply module 1 comprises the following steps: E10: measurement of the load current by the measurement circuit 11, E11: comparison of said measured load current with the predefined load current threshold value Iref, E12: if the measured load current is less than or equal to Iref, cyclic interruption of the switching operation until the value of the measured load current is greater than Iref, E13: measurement of the voltage between the two power supply rails, E14: comparison of the measured voltage with the predefined power supply voltage threshold value Uref, E15: if the measured voltage is greater than or equal to Uref, cessation of the switching operation interruption.

(24) In reference to FIG. 3, the method for controlling the item of equipment 2 comprises the following steps: E20: storage of energy from the switch mode power supply module during the switching operation phase of the switch mode power supply module in a capacitive element connected between the two power supply rails, E21: application between the two power supply rails of the voltage present at the terminals of the capacitive element when the activation signal C1 is in ON state.

(25) These modifications of the power supply module and of the item of equipment make it possible to obtain a device formed of the power supply module and the item of equipment which has a very low residual consumption due to the hiccup mode while retaining a good responsiveness to the commands of the item of equipment.

(26) Though the invention has been described in relation to a specific embodiment, it is evident that this is in no way restricted and that it comprises all technical equivalents of the means described as well as their combinations if these enter into the scope of the invention.