CN100525035C - Switching control device with frequency hopping characteristic - Google Patents

Switching control device with frequency hopping characteristic Download PDF

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Publication number
CN100525035C
CN100525035C CNB2004100946024A CN200410094602A CN100525035C CN 100525035 C CN100525035 C CN 100525035C CN B2004100946024 A CNB2004100946024 A CN B2004100946024A CN 200410094602 A CN200410094602 A CN 200410094602A CN 100525035 C CN100525035 C CN 100525035C
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signal
pulse
switch
switching
width regulating
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CN1777007A (en
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杨大勇
洪国强
林宋宜
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Fairchild Taiwan Corp
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Fairchild Taiwan Corp
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Abstract

Being in use for reducing electromagnetic interference of power supplier, the invention includes a module generator, an oscillator, a programmable capacitance connected to the oscillator, an attenuator connected to a voltage feedback loop, and a programmable resistance connected to the attenuator. Changing digital module code modulates switching frequency so as to generate frequency hopping characteristic. Using the output of the digital module code makes procedure for controlling attenuation ratio of the attenuator. When the switching frequency is increased, attenuation ratio is also increased. Reducing width of pulse wave of the switching signal can be in use for compensating reduction of the switching cycle, and can keep fixed value of output power and output voltage of power supplier.

Description

Switching control device with frequency hopping characteristic
Technical field
The present invention relates to a kind of switching control device, particularly a kind of switching control device of switch mode power supply supply with frequency hopping characteristic.
Background technology
Power supply unit has used widely in the power supply input that will not stablize adjustment and has converted voltage or the electric current that can stablize adjustment to.Fig. 1 shows a known power supply unit.One switching control device 10 produces one and switches signal VPWM power controlling transistor 20, in order to switch a transformer 11.This switching control device 10 comes the pulse bandwidth of this switching signal of modulation VPWM according to a feedback signal VFB.Obtaining of this feedback signal VFB stems from an optical coupler (optical-coupler) 85.One operational amplifier (operational amplifier), 80 and one reference voltage (reference voltage) V REFForm an error amplifier (error amplifier), be used for driving this optical coupler 85.Resistance 72,73 and this error amplifier form a voltage feedback loop, are used for stablizing the output voltage V of adjusting power supply unit oThe primary side switch current I of this transformer 11 PSee through a sensing resistor 30 and convert a switching current signal V to sThis switch current signal V sBe used for supplying with this switching control device 10, switch signal V as this PWMPulse wave width modulation.This switches signal V PWMWork period (duty cycle) the decision power path of transmitting, the path of this power transmission is by the output of power supply input side to power supply unit.
Though the progress of high frequency handoff technique has reduced the size and the volume of power supply unit, but produced electromagnetic interference and then had influence on the power supply quality of power supply input side as the power crystal of diverter switch.One Electromagnetic interference filter (EMI filter), 15 inputs that are positioned over power supply unit are used for reducing electromagnetic interference.Yet this Electromagnetic interference filter 15 has but produced power loss (power consumption) and the cost and the volume that increase power supply unit.In the evolution in recent years, many previous technology are delivered successively, (Applied Power Electronics Conference andExposition APEC) utilizes the frequency modulation (frequency modulation) or the method for frequency hopping to reduce the problem of electromagnetic interference by M.Rahkala, T.Suntio and three propositions of K.Kalliomaki in for example the 17 power application electronic meeting of IEEE in 2002.Yet, when the shortcoming of prior art is frequency modulating, can produce undesired ripple signal (ripple signal) at the output of power supply unit.Mode by frequency modulating produces this ripple signal, can be learnt by following description.The power output of power supply unit is its output voltage V oWith output current I oProduct, known:
P o=V o×I o=η×P IN-----------------------------------------(1)
The input power P of transformer 11 INWith primary side switch current I PCan be expressed as respectively:
P IN = 1 2 × T × L P × I P 2 × η
I P = V IN L P × T ON
Wherein η is the efficient of transformer 11; V INInput voltage for transformer 11; L PInductance value for transformer 11 primary sides; T is for switching signal V PWMSwitching cycle; T ONFor switching signal V PWMON time (on-time).Equation (1) can be write as:
P O = η × V IN 2 × T ON 2 2 × L P × T - - - - - - - - - - - - - - - - - - - - ( 2 )
Switching cycle T changes according to frequency modulating.Shown in equation (2), when switching cycle T changes, power output P oWill along with change.Therefore, as power output P oDuring variation, a undesired ripple signal will generate.
Summary of the invention
Main purpose of the present invention provides a kind of switching control device, and the switching frequency of this switching control device has the characteristic of frequency hopping, makes that the frequency spectrum (spectrum) of this switching frequency is prolonged, and can be used to reduce the electromagnetic interference of power supply unit.Disclosed switching control device will can not produce undesired ripple signal at the output of power supply unit.
Have frequency hopping characteristic according to disclosed switching control device and be applied to power supply unit, comprise a clock pulse generator (clock generator) and be used for producing a clock pulse signal.One module generator is connected in this clock pulse generator, receive this time pulse signal and export a digital module sign indicating number, this module generator comprises a timer and a read-only memory, to produce one or two bit codes, this read-only memory is exported this digital module sign indicating number according to this two bit code to this timer according to this time pulse signal; One pulse-width regulating device is connected in a control end of a power switch, output one is switched signal to this control end, in order to controlling the change action of this power switch, this pulse-width regulating device comprises a comparator, a D type flip-flop and an AND and door, and this comparator is the D type flip-flop that is used for resetting.One oscillator is connected in this pulse-width regulating device, export an oscillation signal to this pulse-width regulating device, can be used to determine one of this switching signal to switch frequency, wherein this switchings signal is used for the stable output of adjusting power supply unit, and is somebody's turn to do the switching signal and time pulse signal is synchronous.But a program electric capacity is connected in this module generator and this oscillator, receives this switching frequency that this digital module sign indicating number comes this oscillator output of modulation, to produce frequency hopping characteristic.
One attenuator is connected to the voltage feedback loop in this power supply unit, receives a feedback signal and this feedback signal of decaying.This feedback signal is used for controlling the pulse bandwidth of this switching signal, and is used for controlling the power output of power supply unit.But a program resistance is connected in this attenuator, this module generator and this pulse-width regulating device, receives this digital module sign indicating number, and carries out the attenuation ratio of this attenuator of sequencing according to this digital module sign indicating number, in order to export a feedback voltage to this pulse-width regulating device.When this switching frequency increased, attenuation ratio also increased thereupon.The pulse bandwidth that reduces this switching signal can be used to compensate the reduction of switching cycle, and makes the power output of power supply unit and output voltage keep fixed value.
Being noted that above general introduction and ensuing detailed description are all exemplary in nature, is in order to further specify claim of the present invention.And about other purpose of the present invention and advantage, will in follow-up explanation and accompanying drawing, be set forth.
Description of drawings
Fig. 1 shows that known power supply unit has an Electromagnetic interference filter;
Fig. 2 shows the embodiment of the switching control device with frequency hopping characteristic;
Fig. 3 shows oscillator according to an embodiment of the invention;
Fig. 4 shows module generator according to an embodiment of the invention;
Fig. 5 shows module generator according to another embodiment of the present invention;
Fig. 6 shows pulse-width regulating device according to an embodiment of the invention.
Symbol description among the figure:
10 switching controllers, 11 transformers
15 Electromagnetic interference filter, 17 DC voltage-stabilizing electric capacity
20 power transistors, 30 current sensing resistors
71 optical coupler resistance, 72 divider resistances
73 divider resistances, 74 compensating resistances
75 building-out capacitors, 80 operational amplifiers
But 85 optical couplers, 100 program resistance
200 oscillators, 210 comparators
220 comparators, 230 NAND gate logical circuits
But 240 NAND gate logical circuits, 290 program electric capacity
300 module generators, 310 timers
320 address ROM datas, 331 buffers
332 buffers, 335 buffers
339 XOR XOR gate
400 clock pulse generators, 500 attenuators
600 pulse-width regulating devices, 610 comparators
620 D type flip-flops, 630 AND and door
Embodiment
Cooperate Fig. 1, Fig. 2 shows according to the embodiment with switching control of frequency hopping characteristic of the present invention.One clock pulse generator 400 produces time pulse signal CK.One module generator 300 is connected in this clock pulse generator 400, receives this time pulse signal CK and exports a digital module sign indicating number [M nM 1].One pulse-width regulating device (PWM control circuit) 600 is connected in a control end of a power switch 20, and signal V is switched in output one PWMTo this control end, in order to control the change action of this power switch 20.One oscillator 200 is connected in this pulse-width regulating device 600, exports an oscillation signal PLS to this pulse-width regulating device 600, can be in order to determine this switching signal V PWMOne switch frequency, wherein should switch signal V PWMBe used for stablizing the output of adjusting power supply unit, and should switch signal V PWMWith time pulse signal CK be synchronous.One programmable electric capacity 290 is connected to this module generator 300 and this oscillator 200, receives this digital module sign indicating number [M nM 1] produce frequency hopping characteristic in order to this switching frequency of this oscillator output of modulation.
One resistance R AWith a resistance R BForm an attenuator 500.This resistance R of this attenuator 500 AFirst end points be connected to a voltage feedback loop, this resistance R AFirst end points receive a feedback signal V FB, and this feedback signal V that decays FBThis feedback signal V FBSee through this pulse-width regulating device 600 and be used for controlling this switching signal V PWMPulse bandwidth, thereby control power supply unit power output.This resistance R ASecond end points be connected to this resistance R BFirst end points.This resistance R BSecond end points be connected to earth terminal with reference to accurate position.One feedback voltage V BIn resistance R BFirst end points on, its voltage signal stems from this attenuator 500.One programmable resistance 100 is connected to this attenuator 500, this module generator 300 and this pulse-width regulating device 600, receives this digital module sign indicating number [M nM 1], and according to this digital module sign indicating number [M nM 1] carry out the attenuation ratio of this attenuator 500 of sequencing, in order to export this feedback voltage V BTo this pulse-width regulating device 600.No matter when switching frequency increases, and attenuation ratio also increases thereupon.Reduce this switching signal V PWMPulse bandwidth can be used to compensate the reduction of switching cycle, and make the power output of power supply unit and output voltage keep fixed value.
But program resistance 100 comprises the suitching type resistor group (switching-resistor set) that is connected in parallel mutually, and this convert resistance group is by several damping resistances R 1, R 2,, R nWith several attenuator switch S 1, S 2, S nForm.Attenuator switch S 1With damping resistance R 1For being connected in series attenuator switch S 2With damping resistance R 2For being connected in series attenuator switch S nWith damping resistance R nIt also is the form of being connected in series.Digital module sign indicating number [M nM 1] control attenuator switch S 1, S 2, S n
But program electric capacity 290 comprises the switch-capacitor group (switching-capacitor set) that is connected in parallel mutually, and this switching type capacitor group is by several oscillating capacitances C 1, C 2,, C nWith several oscillation switch X 1, X 2, X nForm.Oscillation switch X 1With oscillating capacitance C 1For being connected in series oscillation switch X 2With oscillating capacitance C 2For being connected in series oscillation switch X nWith oscillating capacitance C nIt also is the form of being connected in series.Digital module sign indicating number [M nM 1] control oscillation switch X 1, X 2, X n
Fig. 3 shows oscillator 200 according to an embodiment of the invention.One charging current source I 10Produce charging current I CHGOne discharging current source I 20Produce discharging current I DCHGOne vibration charge switch S 31Be connected in charging current source I 10And between the oscillating capacitance C, an oscillating discharge switch S 41Be connected in oscillating capacitance C and discharging current source I 20Between.The anode input of one first comparator 210 provides a critical voltage (threshold voltage) V HThe negative terminal input of this first comparator 210 is connected with oscillating capacitance C.
The negative terminal input of one second comparator 220 provides a critical voltage V L, the positive input of this second comparator 220 is connected with oscillating capacitance C, and critical voltage V HVoltage quasi position be higher than critical voltage V LThe output of one first NAND gate logical circuit 230 produces an oscillation signal PLS, is used for conducting or by this oscillating discharge switch S 41, the first input end of this first NAND gate logical circuit 230 is driven by the output of first comparator 210.Two inputs of one second NAND gate logical circuit 240 are connected respectively to the output of the first NAND gate logical circuit 230 and the output of second comparator 220.The output of this second NAND gate logical circuit 240 is connected to the input of the first NAND gate logical circuit 230, and can be used for conducting or by this vibration charge switch S 31
Fig. 4 shows module generator 300 according to an embodiment of the invention.One timer (timer), 310 outputs according to time pulse signal CK produce one or two bit codes (binary code) [b nB 0].One read-only memory (read-only-memory) 320 is according to this two bit code [b nB 0] output produce digital module sign indicating number [M nM 1].The address input (addressinput) of this read-only memory 320 is driven by the output of this timer 310.
Fig. 5 shows module generator 300 according to another embodiment of the present invention.Several buffers 331,332335 and an XOR XOR gate 339 are formed a linear displacement buffer (linearshift register), and produce a linear code (linearcode) according to the output of time pulse signal CK.The input of this XOR XOR gate 339 determines the multinomial (polynomials) of this linear displacement buffer, and determines the output of this linear displacement buffer.In addition, digital module sign indicating number [M nM 1] can adopt the part that stems from linear code to carry out optimized application.
Fig. 6 shows pulse-width regulating device 600 according to an embodiment of the invention.Pulse-width regulating device 600 comprises a comparator 610, a D type flip-flop 620 and an AND and door 630.This comparator 610 is to be used for replacement (reset) D type flip-flop 620.This feedback voltage V BStem from attenuator 500 and the anode input of supply comparator 610.Switch current signal V SSupply with the negative terminal input of comparator 610.By a supply power voltage V CCDraw (pullhigh) to the accurate position of supply power voltage on the D input with D type flip-flop 620.The clock pulse input (clock input) of D type flip-flop 620 is supplied with by oscillation signal PLS.AND is supplied with by oscillation signal PLS with the first input end of door 630.Second input of AND and door 630 is connected to the output of D type flip-flop 620.AND produces switching signal V with the output of door 630 PWM
Take a broad view of the above, as shown in Figure 3, the capacitance of this oscillating capacitance C of this oscillator 200 determines this switching signal V PWMSwitching frequency, can obtain by following equation:
f S = 1 t on + t off = 1 C × ΔV × I CHG I DCHG I CHG + I DCHG - - - - - - - - - - - - - - - - - - - - ( 3 )
Wherein △ V is critical voltage V HWith V LBetween voltage difference, this switches signal V PWMON time and deadline be expressed as respectively:
t on = C × ΔN I CHG
t off = C × ΔV I DCHG
This programmable electric capacity 290 as shown in Figure 2 receives this digital module sign indicating number [M nM 1] control, this digital module sign indicating number [M nM 1] control those oscillation switch X 1, X 2, X nMake those oscillating capacitances C 1, C 2,, C nIn parallel with this oscillating capacitance C of this oscillator 200, produce frequency hopping characteristic in order to this switching frequency of these oscillator 200 outputs of modulation.
Main purpose of the present invention provides a kind of switching control device, and the switching frequency of this switching control device has the characteristic of frequency hopping, makes that the frequency spectrum of this switching frequency is prolonged, and can be used to reduce the electromagnetic interference of power supply unit.Disclosed switching control device will can not produce undesired ripple signal at the output of power supply unit.
Be familiar with this skill person when carrying out various corrections and change at structure of the present invention at following departing from spirit of the present invention and category not.By aforementioned sight, as long as various correction and change conform with following claim and equivalence is explained, all can be considered a part of the present invention.

Claims (12)

1. switching control device with frequency hopping characteristic is used for controlling the change action of a power switch in a power supply unit, it is characterized in that, includes:
One clock pulse generator is in order to export a clock pulse signal;
One module generator, be connected in this clock pulse generator, receive this time pulse signal in order to export a digital module sign indicating number, this module generator comprises a timer and a read-only memory, to produce one or two bit codes, this read-only memory is exported this digital module sign indicating number according to this two bit code to this timer according to this time pulse signal;
One pulse-width regulating device, be connected in a control end of this power switch, output one switch signal to this control end in order to controlling the change action of this power switch, this pulse-width regulating device comprise a comparator, a D type flip-flop and an AND and, this comparator is the D type flip-flop that is used for resetting;
One oscillator is connected in this pulse-width regulating device, exports an oscillation signal and switches frequency to this pulse-width regulating device in order to determine one of this switching signal, and this switches signal and this time pulse signal is synchronous;
But a program electric capacity is connected to this module generator and this oscillator, receives the control of this digital module sign indicating number, in order to this oscillation signal of this oscillator output of modulation, makes this pulse-width regulating device produce frequency hopping characteristic;
One attenuator is connected to the voltage feedback loop in this power supply unit, receives a feedback signal and this feedback signal of decaying; And
But a program resistance is connected to this attenuator, this module generator and this pulse-width regulating device, receives the control of this digital module sign indicating number, to carry out the attenuation ratio of this attenuator of sequencing, in order to export a feedback voltage to this pulse-width regulating device.
2. the switching control device with frequency hopping characteristic as claimed in claim 1 is characterized in that this feedback signal is used for controlling the pulse bandwidth of this switching signal.
3. the switching control device with frequency hopping characteristic as claimed in claim 1, it is characterized in that, but should program electric capacity form by at least one switching type capacitor group institute that is connected in parallel mutually, this switching type capacitor group is made up of an oscillation switch and the oscillating capacitance institute that is connected in series, and the conducting of this oscillation switch or end and to be controlled by this digital module sign indicating number.
4. the switching control device with frequency hopping characteristic as claimed in claim 1, it is characterized in that, but should program resistance form by at least one suitching type resistor group institute that is connected in parallel mutually, this suitching type resistor group is made up of an attenuator switch and the damping resistance institute that is connected in series, and the conducting of this attenuator switch or end and to be controlled by this digital module sign indicating number.
5. switching control device with frequency hopping characteristic is used for controlling the change action of a power switch in a power supply unit, it is characterized in that, includes:
One clock pulse generator is in order to export a clock pulse signal;
One module generator, be connected in this clock pulse generator, receive this time pulse signal in order to export a digital module sign indicating number, this module generator comprises a timer and a read-only memory, to produce one or two bit codes, this read-only memory is exported this digital module sign indicating number according to this two bit code to this timer according to this time pulse signal;
One pulse-width regulating device, be connected in a control end of this power switch, output one switch signal to this control end in order to controlling the change action of this power switch, this pulse-width regulating device comprise a comparator, a D type flip-flop and an AND and, this comparator is the D type flip-flop that is used for resetting;
One oscillator is connected in this pulse-width regulating device, export an oscillation signal and switch frequency to this pulse-width regulating device in order to determine one of this switching signal, and this switches signal and this time pulse signal is synchronous; And
But a program electric capacity is connected to this module generator and this oscillator, receives the control of this digital module sign indicating number, in order to this oscillation signal of this oscillator output of modulation, makes this pulse-width regulating device produce frequency hopping characteristic.
6. the switching control device with frequency hopping characteristic as claimed in claim 5, it is characterized in that, but should program electric capacity form by at least one switching type capacitor group institute that is connected in parallel mutually, this switching type capacitor group is made up of an oscillation switch and the oscillating capacitance institute that is connected in series, and the conducting of this oscillation switch or end and to be controlled by this digital module sign indicating number.
7. switching control device with frequency hopping characteristic is used for controlling the change action of a power switch in a power supply unit, it is characterized in that, includes:
One clock pulse generator is in order to export a clock pulse signal;
One module generator, be connected in this clock pulse generator, receive this time pulse signal in order to export a digital module sign indicating number, this module generator comprises several buffers and an XOR XOR gate, several buffers according to time pulse signal to produce a linear code, the input of this XOR XOR gate determines the multinomial of this linear code, and determines the output of this module generator;
One pulse-width regulating device, be connected in a control end of this power switch, output one switch signal to this control end in order to controlling the change action of this power switch, this pulse-width regulating device comprise comparator, D type flip-flop and AND and, this comparator is the D type flip-flop that is used for resetting;
One oscillator is connected in this pulse-width regulating device, exports an oscillation signal and switches frequency to this pulse-width regulating device in order to determine one of this switching signal, and this switches signal and this time pulse signal is synchronous;
But a program electric capacity is connected to this module generator and this oscillator, receives the control of this digital module sign indicating number, in order to this oscillation signal of this oscillator output of modulation, makes this pulse-width regulating device produce frequency hopping characteristic;
One attenuator is connected to the voltage feedback loop in this power supply unit, receives a feedback signal and this feedback signal of decaying; And
But a program resistance is connected to this attenuator, this module generator and this pulse-width regulating device, receives the control of this digital module sign indicating number, to carry out the attenuation ratio of this attenuator of sequencing, in order to export a feedback voltage to this pulse-width regulating device.
8. the switching control device with frequency hopping characteristic as claimed in claim 7 is characterized in that this feedback signal is used for controlling the pulse bandwidth of this switching signal.
9. the switching control device with frequency hopping characteristic as claimed in claim 7, it is characterized in that, but should program electric capacity form by at least one switching type capacitor group institute that is connected in parallel mutually, this switching type capacitor group is made up of an oscillation switch and the oscillating capacitance institute that is connected in series, and the conducting of this oscillation switch or end and to be controlled by this digital module sign indicating number.
10. the switching control device with frequency hopping characteristic as claimed in claim 7, it is characterized in that, but should program resistance form by at least one suitching type resistor group institute that is connected in parallel mutually, this suitching type resistor group is made up of an attenuator switch and the damping resistance institute that is connected in series, and the conducting of this attenuator switch or end and to be controlled by this digital module sign indicating number.
11. the switching control device with frequency hopping characteristic is used for controlling the change action of a power switch in a power supply unit, it is characterized in that, includes:
One clock pulse generator is in order to export a clock pulse signal;
One module generator, be connected in this clock pulse generator, receive this time pulse signal in order to export a digital module sign indicating number, this module generator comprises several buffers and an XOR XOR gate, several buffers according to time pulse signal to produce a linear code, the input of this XOR XOR gate determines the multinomial of this linear code, and determines the output of this module generator;
One pulse-width regulating device, be connected in a control end of this power switch, output one switch signal to this control end in order to controlling the change action of this power switch, this pulse-width regulating device comprise a comparator, a D type flip-flop and an AND and, this comparator is the D type flip-flop that is used for resetting;
One oscillator is connected in this pulse-width regulating device, export an oscillation signal and switch frequency to this pulse-width regulating device in order to determine one of this switching signal, and this switches signal and this time pulse signal is synchronous; And
But a program electric capacity is connected to this module generator and this oscillator, receives the control of this digital module sign indicating number, in order to this oscillation signal of this oscillator output of modulation, makes this pulse-width regulating device produce frequency hopping characteristic.
12. the switching control device with frequency hopping characteristic as claimed in claim 11, it is characterized in that, but should program electric capacity form by at least one switching type capacitor group institute that is connected in parallel mutually, this switching type capacitor group is made up of an oscillation switch and the oscillating capacitance institute that is connected in series, and the conducting of this oscillation switch or end and to be controlled by this digital module sign indicating number.
CNB2004100946024A 2004-11-16 2004-11-16 Switching control device with frequency hopping characteristic Active CN100525035C (en)

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US7567066B2 (en) * 2006-10-04 2009-07-28 Power Integrations, Inc. Integrated switch with internally adjusted conduction time
CN101997541B (en) * 2009-08-17 2014-01-01 通嘉科技股份有限公司 Frequency jitter device and method and power management device
CN102082517B (en) * 2009-11-30 2014-03-26 产晶集成电路股份有限公司 Signal converter and method thereof

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