TWI514728B - Multiphase converter controller with current balance - Google Patents

Description

Multiphase power conversion controller with current balance

The invention relates to a multi-phase power conversion controller, in particular to a multi-phase power conversion controller with current balance.

With the evolution of process technology, the integrated circuit has become more and more miniaturized. The miniaturization of the integrated circuit is accompanied by a drop in the driving voltage. However, the power consumption of the integrated circuit in some fields does not decrease proportionally with the decrease of the driving voltage, so that the operating current of the integrated circuit is inversely increased.

The driving voltage source of the integrated circuit is mainly a switching power supply circuit. The switching operation of the switching power supply circuit causes a voltage ripple (Ripple) at the output. These voltage choppings can be noticeable in low operating conditions of the operating voltage, and even cause logic errors in the integrated circuit. In order to reduce the voltage chopping of the switching power supply circuit, a multi-phase DC-to-DC conversion controller has been developed. By multi-channel time-division transmission of power to the output of the DC-to-DC converter circuit, the amount of power transmitted per time can be reduced, thereby reducing the magnitude of voltage chopping.

Please refer to the first figure, which is a circuit diagram of a conventional multi-phase power conversion circuit. The multiphase power conversion circuit includes a controller 10 and three channels 12a-12c. Each of the channels 12a-12c includes two transistor switches connected in series between the input voltage Vin and ground. The drivers in each of the channels 12a-12c receive the pulse width modulation control signals PWM1~PWM3 from the controller 10 to switch the corresponding transistor switches accordingly to provide channel currents Io1~Io3. The channel currents Io1~Io3 combine to form an output current Io to charge an output capacitor Co to generate an output voltage Vout to drive a load. The controller 10 detects the channel power through the pin pairs CSP1 and CSN1, CSP2 and CSN2, CSP3 and CSN3. The streams Io1~Io3 receive a voltage detection signal FB, thereby modulating the duty cycle of the transistor switches in the channels 12a-12c.

Due to the mismatch of the transistor switch and the inductance of each channel, for example, the parasitic resistance mismatch, the current of each phase is unbalanced, that is, the heat of each phase is not balanced. Current imbalance can affect component life and reliability. In order to make the current ripples of the channels 12a~12c similar, the controller 10 adjusts the currents Io1~Io3 of each channel according to the detection signals of the CSP1 and CSN1, CSP2 and CSN2, CSP3 and CSN3. Consistent with each other. Generally, the controller 10 first performs feedback control with an error amplifier to obtain a reference period of the duty cycle of each channel, and then transmits the data to the corresponding pulse width control circuit according to the difference between the channel currents. Perform compensation compensation for the work cycle.

Although the error amplifier works well for suppressing noise, its relative transient response capability is poor, and it cannot respond quickly to load changes. Furthermore, in addition to the complicated circuit, large area, and high cost of the plurality of pulse width control circuits, there are also matching problems between the plurality of pulse width control circuits, which affect the accuracy of current balance of each phase.

The multi-phase power conversion circuit in the prior art has a problem of poor transient response, high circuit complexity, and poor accuracy of current balance. The invention uses the fixed on-time control technology to improve the transient response of the circuit, and uses a single timing circuit to determine the on-time of each phase circuit, which reduces the complexity and cost of the circuit, and also avoids the circuit mismatch affecting the current. The problem of balancing accuracy.

To achieve the above object, the present invention provides a multi-phase power conversion controller with current balancing for controlling a plurality of conversion circuits to collectively provide an output voltage. The multiphase power conversion controller includes a feedback circuit, a fixed on time circuit, and a polyphase logic controller. The feedback circuit detects the output voltage to generate a feedback control signal. The fixed on-time circuit generates a conduction time signal according to the feedback control signal, wherein one of the on-time signals is pulsed The width is determined by a single timing circuit. The multi-phase logic controller selects a corresponding one of the plurality of conversion circuits according to the order of the feedback control signals and generates a phase signal, and controls the corresponding conversion circuit according to the on-time signal. The fixed on-time circuit determines the current correction amount of the corresponding conversion circuit according to the current of the plurality of conversion circuits, and corrects the pulse width of the corresponding on-time signal according to the phase signal.

The above summary and the following detailed description are exemplary in order to further illustrate the scope of the claims. Other objects and advantages of the present invention will be described in the following description and drawings.

Prior art:

10‧‧‧ Controller

12a, 12b, 12c‧‧‧ channels

Co‧‧‧ output capacitor

CSP1, CSN1, CSP2, CSN2, CSP3, CSN3‧‧‧ feet

FB‧‧‧ voltage detection signal

Io‧‧‧ output current

Io1, Io2, Io3‧‧‧ channel current

Load‧‧‧load

PWM1, PWM2, PWM3‧‧‧ pulse width modulation control signal

Vin‧‧‧Input voltage

Vout‧‧‧ output voltage

this invention:

100‧‧‧Multiphase power conversion controller

110, 210‧‧ ‧ feedback circuit

120, 220‧‧‧ fixed on-time circuit

130, 230‧‧‧Multiphase Logic Controller

150a~150c‧‧‧ conversion circuit

152a~152c‧‧‧current detection circuit

212‧‧‧ Comparator

222‧‧‧Error current generating circuit

223‧‧‧Digital error current generating circuit

224‧‧‧ analog digital conversion circuit

226‧‧‧Timekeeping Circuit

227‧‧‧Digital Timing Circuit

232‧‧‧phase number judgment circuit

234‧‧‧Multiphase drive circuit

3221‧‧‧ Current and circuit

3222‧‧‧ average circuit

3223‧‧‧Error calculation circuit

3224‧‧‧Amplification circuit

3261‧‧‧D type flip-flop

3262‧‧‧Fixed current source

3263‧‧‧ Capacitance

3264‧‧‧Adjust current source

3265‧‧‧ comparator

3266‧‧‧ Pulse Width Controller

3267‧‧‧SR flip-flop

3268‧‧‧Switch

△DI_s‧‧‧Digital adjustment current signal

△I_s‧‧‧Adjust current signal

C, D, S‧‧‧ input

Co‧‧‧ output capacitor

DIse_1~n‧‧‧ digital current detection signal

FB‧‧‧ voltage detection signal

Iavg‧‧‧Average current signal

Io1~Io3‧‧‧ channel current

Ise_1~Ise_3, Ise_1~n, Ise_s, Ise_s-1, Ise_s+1‧‧‧ current detection signal

IseX‧‧‧current amplification signal

Isum‧‧‧currents and signals

Ph_s‧‧‧ phase signal

Pon‧‧‧ feedback control signal

Q‧‧‧output

QN‧‧‧inverting output

R‧‧‧Reset end

Ron‧‧ resistance

Sa_1~Sa_3, Sb_1~Sb_3, Sa_s, Sb_s‧‧‧ control signals

Ton_s‧‧‧ On time signal

Vin‧‧‧Input voltage

Vout‧‧‧ output voltage

Vref‧‧‧reference voltage

Von‧‧‧ conduction time reference voltage

The first figure is a circuit diagram of a conventional multi-phase power conversion circuit.

The second figure is a circuit diagram of a multi-phase power conversion circuit with current balancing according to a preferred embodiment of the present invention.

The third figure is a circuit diagram of a multi-phase power conversion controller with current balancing according to a first preferred embodiment of the present invention.

The fourth figure is a circuit diagram of a multi-phase power conversion controller with current balancing according to a second preferred embodiment of the present invention.

Figure 5 is a circuit diagram of a multi-phase power conversion controller with current balancing according to a third preferred embodiment of the present invention.

Figure 6 is a circuit diagram of a timing circuit in accordance with a first preferred embodiment of the present invention.

Figure 7 is a circuit diagram of a timing circuit in accordance with a second preferred embodiment of the present invention.

Figure 8 is a circuit diagram showing an error current generating circuit in accordance with a first preferred embodiment of the present invention.

Figure 9 is a circuit diagram showing an error current generating circuit in accordance with a second preferred embodiment of the present invention.

Please refer to the second figure, which is a circuit diagram of a multi-phase power conversion circuit with current balance according to a preferred embodiment of the present invention. The multi-phase power conversion controller 100 controls a plurality of conversion circuits 150a to 150c to collectively provide an output voltage Vout. In this embodiment, the plurality of conversion circuits are DC-to-DC buck conversion circuits. Each of the conversion circuits includes an upper transistor, a lower transistor, and an inductor. The upper transistor is coupled to an input voltage Vin, and the power of the input voltage Vin is transmitted to an output according to the control of the multi-phase power conversion controller 100. Capacitor Co is stored. The multi-phase power conversion controller 100 includes a feedback circuit 110, a fixed on-time circuit 120, and a multi-phase logic controller 130. The feedback circuit 110 is coupled to an output voltage Vout for detecting the level of the output voltage Vout, and receives a voltage detection signal FB representing the output voltage Vout to generate a feedback control signal Pon accordingly. The multi-phase logic controller 130 selects a corresponding one of the plurality of conversion circuits 150a-150c according to the order of the feedback control signals Pon, and generates a phase signal Ph_s. The plurality of current detecting circuits 152a-152c detect the channel currents Io1~Io3 of the inductors in the plurality of converting circuits 150a-150c to generate current detecting signals Ise_1~Ise_3 representing the channel currents Io1~Io3. The fixed on-time circuit 120 generates an on-time signal Ton_s according to the feedback control signal Pon, wherein the pulse width of one of the on-time signals Ton_s is determined according to a single timing circuit (refer to the following embodiment). The fixed on-time circuit 120 receives the current detecting signals Ise_1~Ise_3, determines the corresponding conversion circuit to be controlled in the period corresponding to the phase signal Ph_s, and determines a correction amount of the current corresponding to the conversion circuit according to the This correction turns on the pulse width of the time signal Ton_s. The multi-phase logic controller 130 determines the on-time of the current period according to the on-time signal Ton_s, and generates corresponding control signals corresponding to the control signals Sa_1~Sa_3, Sb_1~Sb_3 to control the corresponding conversion circuit according to the corresponding conversion circuit to be controlled, wherein the control The signals Sa_1~Sa_3 are used to control the upper transistor of the corresponding conversion circuit, and the control signals Sb_1~Sb_3 are used to control the lower transistor of the corresponding conversion circuit.

Since the fixed on-time circuit 120 of the present embodiment has only a single timing circuit, the complexity and cost of the circuit are lower than those of the conventional circuit, and the use of a single timing circuit also avoids the problem of mismatch between multiple circuits. Therefore, the current of each conversion circuit is more consistent, and the problem of the current life of the components can be avoided by avoiding current unevenness.

Referring to the third figure, there is shown a circuit diagram of a multi-phase power conversion controller with current balancing according to a first preferred embodiment of the present invention. The multiphase power conversion controller includes a feedback circuit 210, a fixed on time circuit 220, and a polyphase logic controller 230. The feedback circuit 210 includes a comparator 212. A non-inverting input terminal of the comparator 212 receives a reference voltage Vref, and an inverting input terminal receives a voltage detection signal FB, and outputs a feedback control signal Pon according to the comparison result. . When a level of the voltage detection signal FB is lower than the reference voltage Vref, the feedback control signal Pon is at a high level. The multiphase logic controller 230 includes a phase number determination circuit 232 and a polyphase drive circuit 234. The phase number judging circuit 232 receives and counts the number of times the feedback control signal Pon is high level to determine which phase of the conversion circuit is scheduled to be controlled in the current cycle according to the result of the counting, and simultaneously outputs a phase signal Ph_s. The fixed on-time circuit 220 includes an error current generating circuit 222 and a timing circuit 226. The error current generating circuit 222 receives the current detecting signals Ise_1~n representing the currents of the respective channels to determine a target value. The error current generating circuit 222 also receives the phase signal Ph_s to determine the difference between the current detecting signal corresponding to the switching circuit to be controlled in the cycle and the target value, and accordingly generates an adjusted current signal ΔI_s. The timing circuit 226 receives the feedback control signal Pon, and accordingly starts the timing program to generate an on-time signal Ton_s, and simultaneously adjusts a pulse width of the on-time signal Ton_s according to the adjustment current signal ΔI_s. The multi-phase driving circuit 234 receives the phase signal Ph_s and the on-time signal Ton_s, generates control signals Sa_s, Sb_s according to the phase-control signal Ph_s corresponding to the conversion circuit to be controlled, and determines the on-time of the cycle according to the on-time signal Ton_s (ie, control) The pulse width of the signal Sa_s).

According to the above description, the fixed on-time circuit 220 of the present invention The conversion circuit corresponding to the scheduled control of the cycle is determined, and the adjustment amount required for the channel current of the conversion circuit to be controlled is determined according to the current detection signal Ise_1~n, and the pulse width of the on-time signal Ton_s is adjusted in the period. For example, if the current of the channel is too small, the pulse width of the corresponding on-time signal Ton_s is longer; if the current of the channel is too large, the pulse width of the corresponding on-time signal Ton_s is shorter. When entering the next cycle of the multi-phase power conversion controller to control the next conversion circuit, the fixed on-time circuit 220 will re-adjust the on-time signal of the next conversion circuit according to the phase signal Ph_s and the current detection signal Ise_1~n. The pulse width of Ton_s. Since the on-time of the conversion circuits of the phases is staggered and non-overlapping, the fixed on-time circuit 220 can provide the information of the on-time required by each phase-converting circuit by using a single timing circuit, thereby avoiding the conventional use of multiple The circuit of the timing circuit does not match the problem.

Please refer to the fourth figure, which is a circuit diagram of a multi-phase power conversion controller with current balance according to a second preferred embodiment of the present invention. Compared with the embodiment shown in FIG. 3 , the fixed on-time circuit 220 of the embodiment additionally adds an analog-to-digital conversion circuit 224 for converting the adjusted current signal ΔI_s generated by the error current generating circuit 222 into a digital adjustment. The current signal ΔDI_s causes the digital timing circuit 227 to digitally adjust the pulse width of the on-time signal Ton_s. Referring to FIG. 5, a circuit diagram of a multi-phase power conversion controller with current balancing according to a third preferred embodiment of the present invention. Compared with the embodiment shown in FIG. 4, before the position of the analog digital conversion circuit 224 is changed to the digital error current generating circuit 223, the current detecting signal Ise_1~n is received first, and converted into a digital current detecting signal DIse_1. ~n. The digital error current generating circuit 223 generates the digital adjustment current signal ΔDI_s according to the digital current detecting signal DIse_1~n and the phase signal Ph_s, so that the digital timing circuit 227 can digitally adjust the pulse width of the on-time signal Ton_s.

6 is a circuit diagram of a timing circuit according to a first preferred embodiment of the present invention. The timing circuit includes a D-type flip-flop 3261, a current source, a capacitor 3263, a pulse width controller 3266, and a switch 3268. An input terminal D of the D-type flip-flop 3261 receives the logic signal of "1", an input terminal C receives the feedback control signal Pon, and a reset terminal R is coupled to the pulse width controller 3266. Please also refer to the third figure. When the level of the voltage detection signal FB is lower than the reference voltage Vref, the feedback control signal Pon is at a high level. At this time, the D-type flip-flop 3261 is triggered to make an output terminal Q and the input terminal D have the same logic state of "1", and an inverting output terminal QN is the opposite logic state (ie, "0"). Thus, switch 3268 is turned off, causing the current source to begin charging capacitor 3263. The current source includes a fixed current source 3262 and an adjusted current source 3264. The fixed current source 3262 provides a fixed current, and the regulated current source 3264 generates an adjustment current according to the adjusted current signal ΔI_s or the digital adjustment current signal ΔDI_s of the above embodiment. Therefore, the current supplied by the current source is the sum of the currents supplied by the fixed current source 3262 and the adjusted current source 3264, and is determined according to the phase signal Ph_s and the current detection signals Ise_1~n of the plurality of conversion circuits. The pulse width controller 3266 includes a comparator 3265 and an SR flip-flop 3267. An input terminal S of the SR flip-flop 3267 receives the feedback control signal Pon. When the feedback control signal Pon is at a high level, the high-level on-time signal Ton_s is outputted at an output terminal Q. That is to say, the feedback control signal Pon determines the starting time point of one of the on-time signals Ton_s. At this time, the multi-phase logic controller 230 starts to conduct the corresponding conversion circuit, so that the level of the voltage detection signal FB rises above the reference voltage Vref, and the feedback control signal Pon turns to the low level signal. One of the comparators 3265 receives an on-time reference voltage Von, and a non-inverting terminal is coupled to the capacitor 3263. When a voltage of the capacitor 3263 is higher than the on-time reference voltage Von, the comparator 3265 outputs a high-level signal to the reset terminal R of the SR flip-flop 3267, so that the SR flip-flop 3267 stops outputting the on-time signal Ton_s. That is to say, an end time point of the on-time signal Ton_s is determined by the on-time reference voltage Von and the voltage of the capacitor 3263. At this time, the D-type flip-flop 3261 is simultaneously reset, so that the inverted output terminal outputs the high-level signal of the logic state "1". Therefore, the switch 3268 is turned on to zero the voltage of the capacitor 3263 to wait for the next cycle (ie, the feedback control signal Pon returns to the high level).

In addition to adjusting the magnitude of the charging current to adjust the pulse width of the on-time signal Ton_s, the present invention can also achieve the same effect by adjusting the level of the on-time reference voltage Von. Referring to the seventh figure, there is shown a circuit diagram of a timing circuit according to a second preferred embodiment of the present invention. Compared with the embodiment shown in FIG. 6, the adjustment current source 3264 is coupled to the on-time reference voltage Von through a resistor Ron, so the voltage received by the inverting terminal of the comparator 3265 varies with the voltage drop of the resistor Ron. The voltage drop of the resistor Ron is caused by the adjustment current flowing through the adjustment current source 3264.

Referring to the eighth figure, there is shown a circuit diagram of an error current generating circuit according to a first preferred embodiment of the present invention. The error current generating circuit includes a current sum circuit 3221, an averaging circuit 3222, and an error calculating circuit 3223. The current and circuit 3221 receives the current detection signals Ise_1~n of the currents of the respective channels to calculate the sum of the currents of the respective channels and output a current and a signal Isum accordingly. The averaging circuit 3222 receives the current and the signal Isum, and calculates a current average value and a corresponding output-average current signal Iavg as a target value. The error calculation circuit 3223 receives the average current signal Iavg and a current detection signal Ise_s corresponding to the conversion circuit to be controlled in the current cycle, and calculates the current of the corresponding conversion circuit and the average current of all the conversion circuits of the multi-phase power conversion circuit. The difference output adjusts the current signal ΔI_s. When the current detecting signal Ise_s is higher than the average current signal Iavg, the adjusting current signal ΔI_s controls the adjusting current source 3264 in the above embodiment, so that the adjusting current source 3264 outputs a positive current to increase the charging current magnitude or modulation of the current source. The voltage received by the inverting terminal of the low comparator 3265. In this way, the on-time of the corresponding conversion circuit can be shortened to reduce the channel current. In contrast, when the current detection signal Ise_s is lower than the average current signal Iavg, the adjustment current signal ΔI_s controls the adjustment current source 3264 in the above embodiment, so that the adjustment current source 3264 outputs a negative current to reduce the charging current of the current source. The voltage received or inverted by the inverting terminal of comparator 3265 is increased. In this way, the on-time of the corresponding conversion circuit can be increased to increase the channel current.

Referring to FIG. 9, a circuit diagram of an error current generating circuit according to a second preferred embodiment of the present invention. Error current generation circuit pack A current and circuit 3221, an amplifying circuit 3224, and an error calculating circuit 3223 are included. The current and circuit 3221 receives the current detection signals Ise_1~s-1 and Ise_s+1~n corresponding to the currents of the respective channels other than the conversion circuit to calculate the sum of the currents of the other channels and output a current and a signal Isum accordingly. The amplifying circuit 3224 receives the current detecting signal Ise_s corresponding to the conversion circuit to be controlled in the current cycle, and amplifies (n-1) times and outputs a current amplifying signal IseX, where n is the total number of channels of the multi-phase power conversion control. The error calculation circuit 3223 receives the average current signal Iavg and the current amplification signal IseX, and outputs an adjustment current signal ΔI_s accordingly. Compared with the embodiment of the eighth embodiment, the embodiment can make the adjustment current signal ΔI_s more reflect the difference between the corresponding channel current and other channel currents.

In summary of the above embodiments, the multiphase power conversion controller of the present invention uses a fixed on-time control technique to improve the transient response of the multi-phase power conversion circuit. Moreover, the multi-phase power conversion controller uses a single timing circuit to determine the on-time of each phase circuit, which reduces the complexity and cost of the circuit, and also avoids the problem that the circuit mismatch affects the accuracy of the current balance.

As described above, the present invention fully complies with the three requirements of the patent: novelty, advancement, and industrial applicability. The invention has been described above in terms of the preferred embodiments, and it should be understood by those skilled in the art that the present invention is not intended to limit the scope of the invention. It should be noted that variations and permutations equivalent to those of the embodiments are intended to be included within the scope of the present invention. Therefore, the scope of the invention is defined by the scope of the following claims.

100‧‧‧Multiphase power conversion controller

110‧‧‧Return circuit

120‧‧‧Fixed on-time circuit

130‧‧‧Multiphase Logic Controller

150a~150c‧‧‧ conversion circuit

152a~152c‧‧‧current detection circuit

Co‧‧‧ output capacitor

FB‧‧‧ voltage detection signal

Io1~Io3‧‧‧ channel current

Ise_1~Ise_3‧‧‧current detection signal

Ph_s‧‧‧ phase signal

Pon‧‧‧ feedback control signal

Sa_1~Sa_3, Sb_1~Sb_3‧‧‧ control signals

Ton_s‧‧‧ On time signal

Vin‧‧‧Input voltage

Vout‧‧‧ output voltage

Claims (7)

A multi-phase power conversion controller with current balance for controlling a plurality of conversion circuits to jointly provide an output voltage, the multi-phase power conversion controller comprising: a feedback circuit for detecting the output voltage to generate a return a control signal; a fixed on-time circuit, based on the feedback control signal to generate an on-time signal, wherein a pulse width of the on-time signal is determined according to a single timing circuit; and a multi-phase logic controller Retrieving the order of the control signals to select a corresponding one of the plurality of conversion circuits and generating a phase signal, and controlling the corresponding conversion circuit according to the on time signal; wherein the fixed on time circuit is based on the plurality of conversions The current of the circuit determines the correction amount of the current of the corresponding conversion circuit for the phase signal, and corrects the pulse width of the corresponding on-time signal accordingly. The multi-phase power conversion controller with current balance according to claim 1, wherein the single timing circuit comprises: a capacitor; a current source for charging the capacitor, the current source is based on the phase signal And detecting a current of the plurality of conversion circuits to determine a charging current provided; and a pulse width controller determining, according to the feedback control signal, the charging current to charge the capacitor and a start time of the on time signal And determining an end time point of the one of the on-time signals according to an on-time reference voltage and a voltage of the one of the capacitors. The multi-phase power conversion controller with current balance according to claim 2, wherein the current source comprises a fixed current source and an adjustment current source, the fixed current source provides a fixed current, and the adjustment current The source determines the magnitude of one of the adjusted currents according to the difference between the current of the corresponding conversion circuit and the average current of the current of the plurality of conversion circuits. The multi-phase power conversion controller with current balance according to claim 2, wherein the current source comprises a fixed current source and an adjustment current source, the fixed current source provides a fixed current, and the adjustment current The source adjusts the current according to the current of the corresponding conversion circuit and one of the other conversion circuits of the plurality of conversion circuits. The multi-phase power conversion controller with current balance according to claim 1, wherein the fixed on-time circuit comprises: a capacitor; a current source that provides a fixed charging current to charge the capacitor; and a pulse width The controller determines, according to the feedback control signal, the charging current to charge the capacitor and a start time point of the on-time signal, and determines an end time of the on-time signal according to an on-time reference voltage and a voltage of the capacitor a point, wherein the on-time reference voltage is determined according to the phase signal and the detection result of the current of the plurality of conversion circuits. The current-balanced multi-phase power conversion controller according to claim 5, wherein the on-time reference voltage is a fixed basic voltage and a regulated voltage, and the adjusted voltage source is corresponding to The difference between the current of the conversion circuit and the average current of one of the plurality of conversion circuits is determined. The multi-phase power conversion controller with current balance according to claim 5, wherein the on-time reference voltage is a voltage sum of a fixed basic voltage and an adjusted voltage, and the adjusted voltage is according to a corresponding conversion circuit. The current is determined by the current sum of one of the other conversion circuits of the plurality of conversion circuits.