CN104181380B - Light load current detection system - Google Patents

Abstract

A light load current detection system is used for detecting the current value of a load in a light load mode and comprises a detection processing module and a control circuit, wherein the detection processing module comprises a power energy-saving unit and a voltage detection module, the power energy-saving unit is used for transmitting a power energy-saving signal, and a period of the power energy-saving signal corresponds to a switching cut-off time or a switching state of a power switch. The voltage detection module is used for detecting an input voltage value of the input voltage source so as to generate and output a detection signal. The control circuit is provided with a data comparison table containing corresponding relations among the period, the current value and the input voltage value, and is provided with a threshold value used for receiving the power saving signal and the detection signal, obtaining the current value according to the data comparison table, judging whether the threshold value is reached or not, and turning off the switch in a light load mode when the judgment result is yes.

Description

Light load current detection system

technical field

The invention relates to a light-load current detection system, in particular to a light-load current detection system for judging whether the current value of the light-load current reaches a threshold according to a data comparison table, and then judging whether to close a switch.

Background technique

With the progress and development of the times, in recent years, the requirements for the efficiency of switching power supply devices such as mobile power supplies have gradually changed from focusing on the efficiency of full load and heavy load to equal emphasis on full load, light load and efficiency. Generally, when a user uses a power adapter to charge a mobile phone, after the battery is fully charged, the screen of the mobile phone will display that the mobile phone has been charged. inconvenient.

In the application of mobile power supply, the light load current detection can make users have better convenience and usability. Furthermore, in the mobile power supply, due to the assistance of the microcontroller (Micro Control Unit; MCU), it can The application circuit is used to detect whether the mobile phone is fully charged, and after the mobile phone is fully charged, the microcontroller will notify the application circuit to cut off the power supply, so that the system can enter a low power consumption or sleep mode.

However, in the existing application circuits for the above-mentioned light-load current detection, specific components are required to realize it. , and then provide this amplified signal to the processor, but this method has the following disadvantages: 1. Because the voltage signal is small, a precision amplifier with low offset (Low Offset) needs to be used, but using this precision amplifier will cause manufacturing The increase in cost and the waste of area are not conducive to the development of light, thin and small. 2. A sensing resistor is needed to convert the load current into a voltage, but the use of this sensing resistor will easily lead to energy loss and low conversion efficiency.

Contents of the invention

In view of the existing light-load current detection application circuits, there are generally problems of high manufacturing cost, high area waste and low conversion efficiency. Therefore, the main purpose of the present invention is to provide a light-load current detection system, which mainly stores a pre-simulated data comparison table in the application circuit, so as to detect the current value of the light-load current according to the data comparison table, To judge whether to close the switch.

Based on the above purpose, the main technical means adopted by the present invention is to provide a light-load current detection system for detecting a current value of a light-load current of a load in a light-load mode, and the load is electrically connected to a switch , The light load current detection system includes a detection processing module and a control circuit. The detection processing module is electrically connected to an input voltage source, and is electrically connected to the load through a switch. The detection processing module includes a power saving unit and a voltage detection module. The power saving unit is used for transmitting a power saving signal in the light load mode, and a cycle of the power saving signal corresponds to a switching cut-off time. The voltage detection module is electrically connected to the input voltage source for detecting an input voltage value of the input voltage source, so as to generate and output a detection signal.

The control circuit is equipped with a data comparison table including the corresponding relationship between cycle, current value and input voltage value, and has a threshold value, and is electrically connected to the power saving unit, the voltage detection module and the switch to receive the power saving signal and the detection signal , so as to obtain the current value according to the data comparison table, the period and the input voltage value, and judge whether the current value reaches the threshold value, so as to close the switch in the light load mode when the judgment result is yes.

In addition, another main technical means adopted by the present invention is to provide a light-load current detection system, which is different from the above-mentioned one in that a power saving signal is transmitted by a power switch, and one cycle of the power saving signal is equal to a switching The switching state is one of the switching time and the number of switching pulses. The above cycle is mainly determined according to the time ratio between the switching of the power switch and the stop switching state; or according to the switching pulse in the power switch It is determined by the quantity, so that the control circuit can obtain the current value according to the data comparison table, the period and the input voltage value, and judge whether the current value reaches the threshold value, so that when the judgment result is yes, the switch is turned off in the light load mode .

Among them, in the preferred embodiment of the auxiliary technical means of the above-mentioned light-load current detection system, the control circuit is a microcontroller (Micro Control Unit; MCU) or other executable processing and control, and the detection processing module further includes a start input terminal, the control circuit is electrically connected to the detection processing module through the start input terminal, so that when the control circuit judges that the current value reaches the threshold value, a shutdown signal is synchronously output to the start input terminal, so as to close the detection processing module and light load Current detection system. In addition, the payload is at least one of a mobile phone, a tablet, and a notebook computer.

With the light-load current detection system adopted in the present invention, since there is no need to use precision amplifiers and sensing resistors, the detection of light-load current can be completed only through the data comparison table, so there will be no problems existing in the prior art. The problems of high manufacturing cost, high area waste and low conversion efficiency.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1 shows the schematic block diagram of the light-load current detection system of the first preferred embodiment of the present invention;

Fig. 2 shows the circuit diagram of the light load current detection system of the first preferred embodiment of the present invention;

Fig. 3 shows the schematic diagram of the data comparison table of the present invention;

FIG. 4 shows a schematic block diagram of a light-load current detection system according to a second preferred embodiment of the present invention; and

FIG. 5 shows the corresponding diagram of the power saving signal and the waveform of the power switch in the present invention.

Among them, reference signs

1. 1a light load current detection system

11, 11a detection processing module

111, 111a power saving unit

112, 112a voltage detection module

113, 113a Start input

114, 114a power switch

115 comparator

116 Compensator

117 Compensation comparator

12, 12a control circuit

2, 2a load

3, 3a switch

4. 4a Input voltage source

S1, S1a power saving signal

S2, S2a detection signal

S3, S3a close signal

S4a Power switching detection signal

I, Ia light load current

t1, t2 time interval

detailed description

In the light-load current detection system provided by the present invention, there are too many combination implementations, so it is not repeated here, and only two preferred embodiments are listed for specific description.

Please refer to FIG. 1 and FIG. 2 together. FIG. 1 shows a schematic block diagram of a light-load current detection system according to a first preferred embodiment of the present invention, and FIG. 2 shows a schematic diagram of a light-load current detection system according to a first preferred embodiment of the present invention. Circuit schematic. As shown in the figure, the light-load current detection system 1 provided by the first preferred embodiment of the present invention is used to detect a current value of a light-load current I of a load 2 in a light-load mode, and the load 2 Electrically connected to a switch 3, wherein the load 2 is at least one of a mobile phone, a tablet, and a notebook computer, but not limited thereto, any device that can be used for charging can be the load described in the present invention.

The light-load current detection system 1 includes a detection processing module 11 and a control circuit 12, the detection processing module 11 is electrically connected to an input voltage source 4, and is electrically connected to the load 2 through a switch 3, wherein the detection processing module 11 For example, it may be a direct current to direct current (DC to DC) processing circuit, but in other embodiments, it is not limited thereto.

The detection processing module 11 is electrically connected to the switch 3 via an inductor (not shown in the figure), a diode (not shown in the figure), a capacitor (not shown in the figure) and two electric groups (not shown in the figure). Varies depending on usage in actual application. The detection processing module 11 includes a power saving unit 111 , a voltage detection module 112 , a start input 113 , a power switch 114 , a comparator 115 , a compensator 116 and a compensation comparator 117 .

The power saving unit 111 can be implemented with a general circuit, the voltage detection module 112 can be implemented with an existing voltage detection circuit, and the voltage detection module 112 is electrically connected to the input voltage source 4 . The start input terminal 113 is, for example, an input pin (pin) of the detection processing module 11 . In addition, the power switch 114 (same as the power switch 114 a in FIG. 4 ) will be described in the second embodiment. The comparator 115 receives a feedback voltage related to the load 2 from the voltage division of the above-mentioned two resistors, and the comparator 115 is provided with a voltage comparison value for comparing with the above-mentioned feedback voltage. The compensator 116 is electrically connected to the comparator 115, and the compensator 116 can be an existing compensation circuit, so it will not be described in detail, and the compensation comparator 117 is electrically connected to the comparator 115 and the compensator 116, and the compensation comparator 117 can be an existing comparator, so it will not be described again.

The control circuit 12 is electrically connected to the power saving unit 111 , the voltage detection module 112 and the switch 3 . In addition, in the first preferred embodiment of the present invention, the control circuit 12 is electrically connected to the detection processing module 11 through the start input terminal 113, and the control circuit 12 is a microcontroller (Micro Control Unit; MCU), and In other embodiments, the control circuit 12 may be a control circuit composed of one of a complex programmable logic device (Complex Programmable Logic Device; CPLD) and an application-specific integrated circuit (Application-Specific Integrated Circuit; ASIC).

Wherein, please refer to FIG. 3 further. FIG. 3 shows a schematic diagram of the data comparison table of the present invention. The power saving unit 111 is used to transmit a power saving signal S1 in the light load mode. A cycle of the power saving signal S1 is the same as Corresponding to the switching cut-off time. Specifically, as shown in FIG. 3 , the cycle referred to in the first preferred embodiment of the present invention is the duty cycle of the power saving signal S1, and its ratio can correspond to the switching cut-off time of the light-load current detection system 1 , in other embodiments may correspond to the cut-off time when the power switch 114 is turned off, but is not limited thereto. The above-mentioned relationship between the cycle and the switching cut-off time can be pre-simulated by simulation software, for example.

In addition, it is worth mentioning that in the first preferred embodiment of the present invention, the power saving signal S1 is related to the load, which is compensated by comparing the feedback voltage with the voltage comparison value of the comparator 115 The power saving signal S1 is determined based on the settings of the comparator 116 and the compensation comparator 117 .

The voltage detection module 112 is used to detect an input voltage value of the input voltage source 4, so as to generate and output a detection signal S2, and the detection signal S2 represents the above-mentioned input voltage value. In the control circuit 12, a data comparison table (as shown in FIG. 3 ) including the corresponding relationship between the period, the current value of the light-load current I and the input voltage value is provided, and a threshold value is provided, and the above-mentioned data comparison table 9 can be It is pre-simulated by simulation software, and the above-mentioned threshold can be set according to the requirements in practical applications.

After receiving the power saving signal S1 and the detection signal S2, the control circuit 12 obtains the current value of the light-load current I according to the data comparison table, the period and the input voltage value, and judges whether the current value reaches the set threshold value, Therefore, when the judgment result is yes, the switch 3 is turned off in the light load mode, and the method of turning it off is, for example, sending a signal (not shown in the figure).

Among them, as shown in Figure 3, the curve 100 is the corresponding relationship between the current value of 5mA and the cycle and the input voltage value, the curve 200 is 10mA, the curve 300 is 20mA, and the curve 400 is 50mA, therefore, the control circuit 12 can be based on this data Check the table to determine the current value of the light load current I. For example, when the input voltage value is 4V, and the control circuit 12 detects that the period is lower than 7.5%, the current value of the corresponding light-load current I is determined to be 10mA. Therefore, when the threshold value is 10mA, the control circuit 12 is to close the switch 3 and enter the low power consumption or dormancy mode.

In addition, when the control circuit 12 determines that the current value reaches the set threshold, it synchronously outputs a shutdown signal S3 to the start input terminal 113, thereby shutting down the detection processing module 11, and then shutting down the light-load current detection system 1, so as to further Reduce power consumption.

Please also refer to FIG. 4 . FIG. 4 shows a block diagram of a light-load current detection system according to a second preferred embodiment of the present invention. As shown in the figure, the difference from the first preferred embodiment is that the detection processing module 11a in the light load current detection system 1a only uses the power saving unit 111a, the voltage detection module 112a and a start input terminal 113a, A power switch 114a is used to detect the light-load current, and the power switch 114a is electrically connected to the power saving unit 111a and the control circuit 12a. In addition, the power switch 114a has the same function as the power switch 114 in the first preferred embodiment. Therefore, only in the second preferred embodiment, the function of the power switch 114a is further described.

Please refer to FIG. 4 and FIG. 5 together. FIG. 5 shows a corresponding diagram of the waveforms of the power saving signal and the power switch in the present invention. As shown in the figure, the power saving unit 111a is used to transmit the power saving signal S1a through the power switch 114a in the light load mode. The period of the power saving signal S1a corresponds to a switching state of the power switch 114a, and the control circuit After receiving the power saving signal S1a, 12a knows the above switching state. In addition, the switching state is one of a switching time and a switching pulse number. In addition, the power saving unit 111a can send the power switching detection signal S4a to the power switch 114a so that the power switch 114a sends the power saving signal S1a, and the operations of other components are the same as those in the first preferred embodiment, so in This will not be repeated here.

For example, when the switching state is the switching time, the switching time refers to the time ratio between the switching of the power switch and the time of stopping switching. Further, as shown in FIG. 5, the time interval t1 is the time interval of the power switching detection signal S4a Operating time (high level), at this time the power switch 114a will stop switching, and the time interval t2 is when the power switching detection signal S4a is at the low level, at this time the power switch 114a will start switching, therefore, the power switch 114a can save energy according to the power The switching time of the power switching detection signal S4a sent by the unit 111a and the switching stop time send out the power saving signal S1a whose cycle corresponds to the switching time. Therefore, the control circuit 12a can use the power saving signal S1a and the detection signal S2a, Find the current value of the current light-load current Ia according to the data comparison table. When the control circuit 12a judges that the current value reaches the threshold value, it synchronously outputs a shutdown signal S3a to the start input terminal 113a, thereby closing the detection processing module 11a. All are the same as those in the first preferred embodiment, and will not be repeated here.

For another example, when the switching state is the number of switching pulses, within the unit time interval (for example, t1+t2 in the second preferred embodiment of the present invention), when the load 2a is light, the time interval t2 will be decrease, so the number of pulses per unit time will also decrease; on the contrary, when the load 2a becomes heavier, the time interval t2 will increase, and the number of pulses per unit time will also increase. Therefore, in practical applications, it can output one cycle corresponding to The power saving signal S1a of the number of pulses enables the control circuit 12a to find out the current value of the current light-load current Ia according to the data comparison table through the power saving signal S1a and the detection signal S2a, and the rest are the same as the above and the first The preferred embodiments are the same and will not be repeated here.

Based on the above, after adopting the light-load current detection system 1 and the method adopted in the present invention, since there is no need to use precision amplifiers and sensing resistors, the light-load current detection can be completed only by using the data comparison table. Therefore, there will be no problems of high manufacturing cost, high area waste, and low conversion efficiency that exist in the prior art, and then achieve the effects of low cost, simplification, and high conversion efficiency, which is in line with industrial applicability.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (9)

1. a kind of underloading current detecting system, in order under a light-load mode, a light current-carrying electric current of detection one load Value, this load is electrically connected at a switch it is characterised in that this underloading current detecting system comprises：

One detection process module, is electrically connected at an input voltage source, and is electrically connected at this load via this switch, this inspection Survey processing module to comprise：One power energy-saving unit, in order under this light-load mode, to send out a power energy-saving signal, this power One cycle of energy-conservation signal is corresponding for deadline with a switching of this underloading current detecting system；And a voltage detection module, It is electrically connected at this input voltage source, in order to detect an input voltage value of this input voltage source, use and produce and export an inspection Survey signal；And

One control circuit, is provided with the data synopsis of a corresponding relation comprising this cycle, this current value and this input voltage value, And be provided with a threshold value, and it is electrically connected at this power energy-saving unit, this voltage detection module and this switch, in order to receive this power Energy-conservation signal and this detection signal, use according to this data synopsis, this cycle and this input voltage value, draw this current value, And judge whether this current value reaches this threshold value, in order to when judged result is to be, to close this under this light-load mode and to open Close.

2. underloading current detecting system according to claim 1 is it is characterised in that this control circuit is a microcontroller.

3. underloading current detecting system according to claim 1 is it is characterised in that this detection process module further includes one and opens Dynamic input, this control circuit is electrically connected at this detection process module via this startup input, uses in this control circuit When judging that this current value reaches this threshold value, synchronism output one shutdown signal, to this startup input, is closed at this detection according to this Reason module.

4. underloading current detecting system according to claim 1 is it is characterised in that this load is a mobile phone, flat board, notes At least one of type computer.

5. a kind of underloading current detecting system, in order under a light-load mode, a light current-carrying electric current of detection one load Value, this load is electrically connected at a switch it is characterised in that this underloading current detecting system comprises：

One detection process module, is electrically connected at an input voltage source, and is electrically connected at this load via this switch, this inspection Survey processing module to comprise：One power energy-saving unit, is electrically connected at a power switch, in order under this light-load mode, by this Power switch sends out a power energy-saving signal, a switching state phase of a cycle of this power energy-saving signal and this power switch Corresponding；And a voltage detection module, it is electrically connected at this input voltage source, in order to detect an input electricity of this input voltage source Pressure value, uses and produces and export a detection signal；And

One control circuit, is provided with the data synopsis of a corresponding relation comprising this cycle, this current value and this input voltage value, And be provided with a threshold value, and it is electrically connected at this power switch, this voltage detection module and this switch, in order to receive this power energy-saving Signal and this detection signal, use according to this data synopsis, this cycle and this input voltage value, draw this current value, and Judge whether this current value reaches this threshold value, in order to when judged result is to be, to close this switch under this light-load mode.

6. underloading current detecting system according to claim 5 it is characterised in that this switching state be a switching time with One of one switching umber of pulse.

7. underloading current detecting system according to claim 5 is it is characterised in that this control circuit is a microcontroller.

8. underloading current detecting system according to claim 5 is it is characterised in that this detection process module further includes one and opens Dynamic input, this control circuit is electrically connected at this detection process module via this startup input, uses in this control circuit When judging that this current value reaches this threshold value, synchronism output one shutdown signal, to this startup input, is closed at this detection according to this Reason module.

9. underloading current detecting system according to claim 5 is it is characterised in that this load is a mobile phone, flat board, notes At least one of type computer.