Switching Power Supply frequency setting circuit, method and electronic equipment
Technical field
The present invention relates to power technique fields, more particularly, relate to a kind of Switching Power Supply frequency setting circuit, method and electronic equipment.
Background technology
Along with electronic equipment especially communication power rectifier module is towards the future development of high power density, low cost and low standby power loss, Overall Power Consumption requires more and more less.How effectively to reduce Switching Power Supply power consumption and become problem demanding prompt solution.
Wherein, the power consumption reduced under holding state is particularly important.Stand-by power consumption when mainly accessory power supply is standby efficiency and standby time load to determine.When load is difficult to change, efficiency when accessory power supply is standby is just extremely important, and when module is standby, accessory power supply is operated in light condition, and efficiency is generally lower; And along with the requirement of module high power density and low cost, accessory power supply switching frequency is higher, reduce further efficiency, makes module stand-by power consumption be difficult to meet customer requirement.For this reason, different electrical power producer uses various different accessory power supply scheme, meets the requirement of stand-by power consumption.
The accessory power supply scheme that current industry is commonly used is as follows:
1, adopt the controller of integrated MOS pipe, controller adjusts switching frequency according to loading condition.But adopt integrated metal-oxide-semiconductor, withstand voltage general below 800V, when module thunderbolt or surge, metal-oxide-semiconductor is difficult to meet voltage derate and reliability requirement; And the chip package of different manufacturers is different, is difficult to compatible design, when producing scarce material, without alternative scheme, impact delivery; The controller scheme cost of integrated MOS pipe is general also relatively high.
2, adopt quasi resonant control to add external metal-oxide-semiconductor, controller adjusts switching frequency according to loading condition.But the chip package of different manufacturers is different, is difficult to compatible design, when producing scarce material, without alternative scheme, impact delivery; And quasi resonant control switching frequency when load is different is different, and different switching frequency EMI is different, causes EMI debug difficulties; Different switching frequencies is also different to the interference controlling sample circuit, and frequency spectrum relative abundance, is difficult to filtering, also affects sampling.
3, lower switching frequency and the better switching device of performance is adopted.And lower switching frequency needs larger magnetic device and filtering device, cost is relatively high.
In order to meet module low cost and device all needs alternative designing requirement, the switching device scheme of fixing high switching frequency control chip and low cost poor performance can be selected during accessory power supply design, but the stand-by power consumption of this scheme is difficult to meet specification requirement.
Referring to Fig. 1, is the circuit theory diagrams of prior art breaker in middle supply frequency initialization circuit.As shown in Figure 1, this Switching Power Supply frequency setting circuit, at least comprises: power supply master chip U1, the first resistance R1 and the first electric capacity C1.Power supply master chip U1 is the control chip of design Switching Power Supply, such as, adopt current type PWM control chip, as the chip of model UC3842.This first resistance R1 and the first electric capacity C1 is connected on the reference voltage output end VREF(pin 8 of power supply master chip U1) and ground GND(pin 5) between, the node between the first resistance R1 and the first electric capacity C1 is connected to the timing end RT/CT(pin 4 of power supply master chip U1).Above-mentioned device constitutes a universal frequency initialization circuit of Switching Power Supply.According to chip data, the circuit oscillator frequency f=1.8/ (C of power supply master chip U1 inside
tr
t).Wherein, the first electric capacity C1 is as electric capacity C
t, the first resistance R1 is as resistance R
t.Therefore, the frequency of Switching Power Supply is f=1.8/ (C
1r
1), determined by the value of the first resistance R1 and the first electric capacity C1.In this universal frequency initialization circuit, no matter be holding state or open state, the frequency of this Switching Power Supply is all constant, therefore effectively cannot reduce the loss of power, especially power standby loss.
Summary of the invention
The technical problem to be solved in the present invention is, be difficult to the defect realizing low-power consumption when controlling cost when designing for existing power supply, a kind of the Switching Power Supply frequency setting circuit, method and the electronic equipment that reduce power consumption by controlling power supply master chip switching frequency are provided.
The technical solution adopted for the present invention to solve the technical problems is: construct a kind of Switching Power Supply frequency setting circuit, comprise: power supply master chip, the first resistance and the first electric capacity, between the reference voltage output end being connected to power supply master chip after described first resistance and the first capacitances in series and ground, the node between described first resistance and the first electric capacity connects the timing end of power supply master chip; Described Switching Power Supply frequency setting circuit also comprises: the second electric capacity and the first on-off element; Described first electric capacity two ends are connected to after described second electric capacity and the first switch elements in series; Described first on-off element is also connected to a frequency control terminal, and disconnect described second electric capacity place branch road when receiving first frequency control signal power supply master chip is switched to the first switching frequency, when receiving second frequency control signal, described in conducting, power supply master chip is switched to the second switch frequency lower than described first switching frequency by the second electric capacity place branch road.
According in Switching Power Supply frequency setting circuit of the present invention, described frequency control terminal is connected to the Opportunity awaiting control for linear end of mainboard, receive open state signal as described first frequency control signal, receive holding state signal as described second frequency control signal.
According in Switching Power Supply frequency setting circuit of the present invention, described first on-off element is MOSFET; Described first frequency control signal is low level, and described second frequency control signal is high level.
Present invention also offers a kind of electronic equipment, comprise mainboard and power panel, described power panel has a Switching Power Supply frequency setting circuit, this Switching Power Supply frequency setting circuit at least comprises: power supply master chip, the first resistance and the first electric capacity, between the reference voltage output end being connected to power supply master chip after described first resistance and the first capacitances in series and ground, the node between described first resistance and the first electric capacity connects the timing end of power supply master chip; Described Switching Power Supply frequency setting circuit also comprises: the second electric capacity and the first on-off element; Described first electric capacity two ends are connected to after described second electric capacity and the first switch elements in series; Described first on-off element is also connected to a frequency control terminal, and disconnect described second electric capacity place branch road when receiving first frequency control signal power supply master chip is switched to the first switching frequency, disconnect described second electric capacity place branch road when receiving second frequency control signal and power supply master chip is switched to second switch frequency lower than described first switching frequency.
According in electronic equipment of the present invention, described frequency control terminal is connected to the Opportunity awaiting control for linear end of mainboard, receives open state signal as described first frequency control signal, receives holding state signal as described second frequency control signal.
According in electronic equipment of the present invention, described first on-off element is MOSFET; Described first frequency control signal is low level, and described second frequency control signal is high level.
Present invention also offers a kind of Switching Power Supply frequency setting method, comprising:
First switching frequency switch step: when receiving first frequency control signal, disconnect the first on-off element, between the reference voltage output end being connected to power supply master chip after making the first electric capacity and the first resistant series and ground, and the node between described first electric capacity and the first resistance is connected to the timing end of power supply master chip to provide the first switching frequency;
Second switch frequency switching step: when receiving second frequency control signal, conducting first on-off element, after making the second electric capacity and the first Capacitance parallel connection and the first resistant series between the reference voltage output end and ground of power supply master chip, and the node between described first resistance and two electric capacity is connected to the timing end of power supply master chip to provide the second switch frequency lower than described first switching frequency.
According in Switching Power Supply frequency setting method of the present invention, the open state signal that the Opportunity awaiting control for linear end that described first frequency control signal comprises mainboard sends, the holding state signal that the Opportunity awaiting control for linear end that described second frequency control signal comprises mainboard sends.
According in Switching Power Supply frequency setting method of the present invention, described first on-off element adopts MOSFET; Described first frequency control signal is low level, and described second frequency control signal is high level.
Implement Switching Power Supply frequency setting circuit of the present invention, method and electronic equipment, there is following beneficial effect: the present invention controls the frequency of operation of power supply master chip as required by setting up on-off element and electric capacity, to regulate it to be positioned at the different frequency state of height two, achieve the object reducing Switching Power Supply power consumption; And power supply master chip of the present invention is general-purpose device, has substitutability, in Switching Power Supply, the selection of metal-oxide-semiconductor is not also by the restriction of power supply power consumption, and its circuit is simple, advantage of lower cost, adapts to the requirement of module low-cost design.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described, in accompanying drawing:
Fig. 1 is the circuit theory diagrams of prior art breaker in middle supply frequency initialization circuit;
Fig. 2 is the circuit theory diagrams of the first embodiment according to Switching Power Supply frequency setting circuit of the present invention;
Fig. 3 is the circuit theory diagrams of the second embodiment according to Switching Power Supply frequency setting circuit of the present invention;
Fig. 4 is the schematic diagram of the preferred embodiment according to electronic equipment of the present invention;
Fig. 5 is the process flow diagram of the preferred embodiment according to Switching Power Supply frequency setting method of the present invention.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.
Referring to Fig. 2, is the circuit theory diagrams of the first embodiment of Switching Power Supply frequency setting circuit according to the present invention.As shown in Figure 2, the Switching Power Supply frequency setting circuit that this embodiment provides, comprising: power supply master chip U1, the first resistance R1, the first electric capacity C1, the second electric capacity C2 and the first on-off element S1.Power supply master chip U1 is that power supply master chip U1 can know for this area basic technology personnel and can be used for designing the control chip of Switching Power Supply, such as, adopt current type PWM control chip.Between the reference voltage output end that this first resistance R1 and the first electric capacity C1 is connected on power supply master chip U1 and ground, the node between the first resistance R1 and the first electric capacity C1 is connected to the timing end of power supply master chip U1.Second electric capacity C2 is connected in parallel on the first electric capacity C1 two ends after connecting with the first on-off element S1.First on-off element S1 is also connected to a frequency control terminal STB.This frequency control terminal STB can receive first frequency control signal and second frequency control signal.Wherein, the frequency that first frequency control signal is used for gauge tap power supply is in the first switching frequency f, and the frequency that second frequency control signal is used for gauge tap power supply is in second switch frequency f '.Wherein, second switch frequency f ' lower than the first switching frequency f.First on-off element S1 is used for disconnecting the second electric capacity C2 place branch road when receiving first frequency control signal from frequency control terminal STB, and then power supply master chip U1 can be switched to the first switching frequency f.First on-off element S1 is used for the conducting second electric capacity C2 place branch road when receiving second frequency control signal from frequency control terminal STB, and then power supply master chip U1 is switched to second switch frequency f '.
Referring to Fig. 3, is the circuit theory diagrams of the second embodiment of Switching Power Supply frequency setting circuit according to the present invention.As shown in Figure 3, model is adopted to be that the chip of UC3842 is as power supply master chip U1 in the Switching Power Supply frequency setting circuit that this embodiment provides.And the first on-off element S1 adopts switching tube Q1 to realize.This Switching Power Supply frequency setting circuit comprises: power supply master chip U1, the first resistance R1, the first electric capacity C1 second electric capacity C2 and switching tube Q1.This first resistance R1 and the first electric capacity C1 is connected on the reference voltage output end VREF(pin 8 of power supply master chip U1) and ground GND(pin 5) between, the node between the first resistance R1 and the first electric capacity C1 is connected to the timing end RT/CT(pin 4 of power supply master chip U1).The first electric capacity C1 two ends are connected to after second electric capacity C2 connects with switching tube Q1.This switching tube Q1 is also connected to frequency control terminal STB.Switching tube Q1 disconnects the second electric capacity C2 place branch road when receiving first frequency control signal by frequency control terminal STB, first electric capacity C1 first resistance R1 is connected between the reference voltage output end VREF of power supply master chip U1 and ground GND together, and the node between the first resistance R1 and the first electric capacity C1 is connected to the timing end RT/CT of power supply master chip U1 to provide the first switching frequency f.Now the frequency of Switching Power Supply i.e. the first switching frequency f is power supply master chip U1 internal circuit oscillator frequency, is determined, f=1.8/ (C by the value of the first resistance R1 and the first electric capacity C1
tr
t)=1.8/ (C
1r
1).Switching tube Q1 is conducting second electric capacity C2 place branch road when receiving second frequency control signal, second electric capacity C2 is connected between the reference voltage output end VREF of power supply master chip U1 and ground GND after the first electric capacity C1 parallel connection together with the first resistance R1, and the node between first resistance R1 and two electric capacity is connected to the timing end RT/CT of power supply master chip U1 to provide second switch frequency.Now the circuit oscillator frequency of power supply master chip U1 is determined by the value of the first resistance R1, the first electric capacity C1 and the second electric capacity C2, f '=1.8/ (C
tr
t)=1.8/ ((C1+C2) * R1).More known through numeric ratio, second switch frequency f ' < first switching frequency f.Therefore, the frequency of operation of power supply master chip can be controlled as required by Switching Power Supply frequency setting circuit of the present invention, to regulate it to be positioned at the different frequency state of height two, reduce Switching Power Supply power consumption when needed.
Aforementioned frequencies control end STB can be connected to the Opportunity awaiting control for linear end of mainboard, to receive open state signal that mainboard sends as first frequency control signal, receives holding state signal as second frequency control signal.Therefore, the present invention can keep higher switching frequency when open state, and when standby, reduce switching frequency, achieves the object reducing stand-by power consumption.
In a preferred embodiment of the invention, frequency control terminal STB can also be connected to the signal port beyond the Opportunity awaiting control for linear end of mainboard.A level signal can be sent to frequency control terminal STB under open state as second frequency control signal as required by the signal port beyond Opportunity awaiting control for linear end, even if like this under non-standby state, the state that also can control to make power supply master chip U1 be in low switching frequency by signal improves the efficiency of Switching Power Supply.
In the present invention, the first on-off element S1 can be MOSFET(metal-oxide half field effect transistor as previously mentioned), or the bilateral switching element of other type.As being described for MOSFET in the present embodiment, the drain electrode of switching tube Q1 connects one end of the second electric capacity C2, and the source electrode of switching tube Q1 connects the ground GND(pin 5 of power supply master chip U1), the grid of switching tube Q1 meets frequency control terminal STB.Aforementioned first frequency control signal is low level, and second frequency control signal is high level.Such as, when frequency control terminal connects the Opportunity awaiting control for linear end of mainboard, the holding state signal that the Opportunity awaiting control for linear end of mainboard sends is high level, and open state signal is low level.Switching tube Q1, when receiving high level, is in conducting state, now the second electric capacity C2 is accessed switching frequency initialization circuit, makes the frequency error factor of Switching Power Supply be second switch frequency f '.Switching tube Q1, when receiving low level, is in cut-off state, now disconnects, the second electric capacity C2 place branch road by the frequency error factor of Switching Power Supply to the first higher switching frequency f.In a preferred embodiment of the invention, also high level signal can be sent to frequency control terminal STB under open state by the signal port beyond Opportunity awaiting control for linear end as required, even if Master control chip U1 also can be controlled like this be in lower second switch frequency to improve the efficiency of Switching Power Supply under non-standby state.
Carry out detecting contrast to the power of circuit of the present invention by experiment, when employing universal frequency initialization circuit, namely before not setting up the first on-off element S1 and the second electric capacity C2, complete machine stand-by power consumption is 4.6W, do not meet the specification requirement that complete machine stand-by power consumption is less than 4W, increase the first on-off element S1 and the second electric capacity C2 and after adopting Opportunity awaiting control for linear end to carry out start and Opportunity awaiting control for linear, stand-by power consumption is 3.8W, meets specification requirement.And power supply master chip of the present invention is general-purpose device, has substitutability, in Switching Power Supply, the selection of metal-oxide-semiconductor is not also by the restriction of power supply power consumption, and its circuit is simple, advantage of lower cost, adapts to the requirement of module low-cost design.
The present invention is also corresponding provides a kind of electronic equipment, comprises mainboard and power panel.This power panel has foregoing Switching Power Supply frequency setting circuit.Electronic equipment of the present invention like this can control the frequency of operation of power supply master chip as required, to regulate it to be positioned at the different frequency state of height two, reduces Switching Power Supply power consumption.Referring to Fig. 4, is the schematic diagram of the preferred embodiment of electronic equipment according to the present invention.As shown in Figure 4, this electronic equipment comprises mainboard 20 and power panel 10.This power panel 10 has foregoing Switching Power Supply frequency setting circuit, namely comprises power supply master chip U1, the first electric capacity C1, the second electric capacity C2, the first resistance R1 and the first on-off element S1.Mainboard 20 has Opportunity awaiting control for linear end 21, for sending standby signal and open state signal.Switching Power Supply frequency setting circuit medium frequency control end STB is connected to the Opportunity awaiting control for linear end 21 of mainboard 20, to receive open state signal that mainboard 20 sends as first frequency control signal, receives holding state signal as second frequency control signal.In the standby state, power supply master chip U1 is switched to second switch frequency f by the first on-off element S1 conducting second electric capacity C2 place branch road when receiving holding state signal ', when making standby, the frequency of Switching Power Supply is in lower value.Under open state, disconnect the second electric capacity C2 place branch road when the first on-off element S1 receives open state signal and power supply master chip U1 is switched to the first switching frequency f, make the frequency of Switching Power Supply during start be in high value.Therefore, the Switching Power Supply of this electronic equipment can keep higher switching frequency when open state, reduces switching frequency when holding state, reduces stand-by power consumption.
In a preferred embodiment of the invention, frequency control terminal STB can also be connected to the signal port beyond the Opportunity awaiting control for linear end 21 of mainboard 20.A level signal can be sent to frequency control terminal STB under open state as second frequency control signal as required by the signal port beyond this Opportunity awaiting control for linear end 21, even if like this under non-standby state, the state that also can control to make Master control chip U1 be in low switching frequency by signal improves the efficiency of Switching Power Supply.Preferably, the first on-off element S1 can be the two-way switch of MOSFET or other types.When the first on-off element S1 selects MOSFET, first frequency control signal is low level, and second frequency control signal is high level.Such as, open state signal is low level, and holding state signal is high level, under open state, also can send high level signal to reduce the frequency of Switching Power Supply to frequency control terminal.
The present invention is also corresponding provides a kind of Switching Power Supply frequency setting method, comprises first frequency switch step and second frequency switch step.This Switching Power Supply frequency setting method can be applied in aforementioned switches supply frequency initialization circuit.Referring to Fig. 5, is the process flow diagram of the preferred embodiment of Switching Power Supply frequency setting method according to the present invention.As shown in Figure 5, the Switching Power Supply frequency setting method that this embodiment provides comprises the following steps:
In first frequency switch step shown in step 501, the first on-off element S1 is disconnected when receiving first frequency control signal, be connected to after first electric capacity C1 is connected with the first resistance R1 between the reference voltage output end VREF of power supply master chip U1 and ground GND, and the node between the first electric capacity C1 and the first resistance R1 is connected to the timing end RT/CT of power supply master chip U1 to provide the first switching frequency f.
In second frequency switch step shown in step 502, the conducting first on-off element S1 when receiving second frequency control signal, after making the second electric capacity C2 in parallel with the first electric capacity C1 and the first resistance R1 be connected on power supply master chip U1 reference voltage output end VREF and ground GND between, and the node between first resistance R1 and two electric capacity is connected to the timing end RT/CT of power supply master chip U1 to provide second switch frequency f '.
Wherein, the open state signal that first frequency control signal can send for the Opportunity awaiting control for linear end of mainboard, the holding state signal that second frequency control signal can send for the Opportunity awaiting control for linear end of mainboard.The level signal that second frequency control signal can also send under open state for the signal port beyond Opportunity awaiting control for linear end, even if like this under non-standby state, the state that also can control to make Master control chip U1 be in low switching frequency by signal improves the efficiency of Switching Power Supply.Preferably, the first on-off element S1 can be the two-way switch of MOSFET or other types.When the first on-off element S1 selects MOSFET, first frequency control signal is low level, and second frequency control signal is high level.
The present invention is described according to specific embodiment, but it will be understood by those skilled in the art that when not departing from the scope of the invention, can carry out various change and equivalent replacement.In addition, for adapting to specific occasion or the material of the technology of the present invention, can many amendments be carried out to the present invention and not depart from its protection domain.Therefore, the present invention is not limited to specific embodiment disclosed herein, and comprises all embodiments dropping into claims.