CN117811368A - Single-inductor multi-output DC-DC converter - Google Patents

Abstract

The invention provides a single-inductor multi-output DC-DC converter, which comprises: the switching circuit comprises a change-over switch assembly, an inductor, at least two output branches and a voltage detection circuit, wherein the change-over circuit is used for determining whether an overvoltage protection signal of each output branch is effective or not and determining whether a voltage too low signal of each output branch is effective or not; a logic control module and an instant switching module that control the transfer switch assembly to charge or discharge the inductor. The instant switching module immediately controls the branch switch of one output branch to be conducted when the voltage over-low signal of the output branch is effective so as to immediately charge the output branch. In this way, the energy distribution problem of each output branch can be handled faster and better in the face of a strongly varying load current.

Description

Single-inductor multi-output DC-DC converter

[ field of technology ]

The invention relates to the field of power supplies, in particular to a single-inductor multi-output direct current-direct current converter with quick response.

[ background Art ]

A single-inductor multi-output DC-DC converter (SIMO-DCDC) adopts a mode of sharing inductors, so that the number of package pins and off-chip inductors is reduced, a plurality of different output voltages are provided, the cost of off-chip components is reduced, and the power efficiency is improved. However, the single-inductor multi-output dc-dc converter cannot flexibly handle the current variation of different loads of each output branch, and unnecessary overshoot and undershoot may occur in the output voltages of different loads.

The peak current mode in the existing single-inductor multi-output DC-DC converter control mode is one of the common feedback control methods. The voltage mode control is different from the voltage mode control, taking output voltage hysteresis control and an inductor current peak-valley value fixed control mode as examples, and simultaneously feeding back an output voltage signal and an inductor current to form voltage outer loop current inner loop double feedback. The dual loop inductor current peak to valley fixed control mode has many advantages over single loop voltage mode control and is therefore widely used. The ripple of the output voltage also depends on the peak current threshold of the inductor set, which becomes a key point. If the setting is small, the ripple wave becomes small, but when the load current becomes large, the output voltage may be kept still, and especially when the load change is large, the value of the peak current threshold becomes difficult.

The existing single-inductor multi-output direct current-direct current converter mainly adopts digital circuit control based on a state machine to control the energy distribution sequence of each branch, and when the load of each branch changes, the single-inductor multi-output direct current-direct current converter cannot simply carry out round robin charging according to a specific charging sequence. If a certain branch is charged, the load jumps from heavy load to light load, and charging is not stopped in time, larger overshoot is brought. If a branch is charged, the load jumps from light load to heavy load, and a larger undershoot voltage can occur if the branch is not charged in time. Both of these situations are detrimental to the stability of the powered system.

When multiple branches need to be charged at the same time, the single-inductor multiple-output direct current-direct current converter sequentially carries out round robin charging on all the branches, and the charging sequence of the single-inductor multiple-output direct current-direct current converter is mainly determined by a state machine. When the load current of n branches jumps from light to heavy, the branches need to wait for up to n-1 charging pulses (pulses). If the system can not be switched to the branch circuit in time for chargingIt will likely result in a large undershoot voltage. Let the period of one charge pulse be T. The worst case is that the last charged branch load jumps from light load to heavy load, and the undershoot voltage is Δvundershoot=i _load *(n-1)*T/C _load ，I _load For the load current of the branch, C _load Which is the output capacitance of the branch.

Accordingly, there is a need for a new solution to overcome one or more of the above-mentioned problems.

[ invention ]

It is therefore an object of the present invention to provide a fast-response single-inductor multi-output dc-dc converter that can more quickly and better address the energy distribution problem of each output branch in the face of a strongly varying load current.

According to one aspect of the present invention, the present invention proposes a single-inductor multiple-output dc-dc converter comprising: the switching circuit comprises an input power supply end, a switching assembly, an inductor and at least two output branches, wherein each output branch comprises a branch output end and a branch switch; the voltage detection circuit is configured to determine whether an overvoltage protection signal of each output branch is effective according to the feedback voltage of each output branch, wherein the overvoltage protection signal of each output branch effectively indicates that the output branch does not need to be charged, the overvoltage protection signal of each output branch is invalid to indicate that the output branch needs to be charged, the voltage of each output branch effectively indicates that the voltage of the output branch is too low, and the voltage of each output branch is not too low; a logic control module configured to control the transfer switch assembly such that the inductor is charged or discharged; and the instant switching module is configured to immediately control the on state of the branch switch of one output branch and the off state of the branch switch of other output branches when the voltage too low signal of the output branch is valid so as to immediately charge the output branch.

Compared with the prior art, the instant switching module in the invention immediately controls the on of the branch switch of one output branch and the off of the branch switch of other output branches when the voltage too low signal of the output branch is effective so as to immediately charge the output branch, thus being capable of better and faster solving the energy distribution problem of each output branch when facing to the severe load current.

[ description of the drawings ]

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:

fig. 1 is a schematic circuit diagram of a conventional single-inductor multi-output dc-dc converter;

fig. 2 is a schematic circuit diagram of a single-inductor multi-output dc-dc converter according to the present invention;

fig. 3 is a schematic diagram illustrating an operation principle of the single-inductor multi-output dc-dc converter in fig. 2;

FIG. 4 is a schematic diagram of signals of a conventional single-inductor multiple-output DC-DC converter in an application example;

FIG. 5 is a schematic diagram of signals of the single-inductor multiple-output DC-DC converter of FIG. 2 in one example application;

FIG. 6 is a schematic circuit diagram of the instant switch module of FIG. 2 in one embodiment;

FIG. 7 is a schematic circuit diagram of the reverse current protection adaptive module in FIG. 2 in one embodiment;

fig. 8 is a schematic circuit diagram of the overcurrent protection adaptive module in fig. 2 in one embodiment.

[ detailed description ] of the invention

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic may be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Unless specifically stated otherwise, the terms connected, coupled, and connected herein denote an electrical connection, either directly or indirectly.

Fig. 1 shows a conventional single-inductor multiple-output dc-dc converter. As shown in fig. 1, the single-inductor multi-output dc-dc converter includes a conversion circuit, a voltage acquisition module 120, a voltage detection module 130, a logic control module 140, an overcurrent protection (Over Current Protection) module 150, and a reverse current protection (Reverse Current Protection) module 160. The switching circuit includes a first switch PM0 and a second switch NM0 connected between the input power supply terminal VDD and the ground terminal, an inductance L1 connected between the intermediate nodes SW1 (connection nodes of the first switch PM0 and the second switch NM 0) and SW2, and n output branches connected to the intermediate node SW 2. Each output branch comprises a branch switch M1-Mn, a branch output Vout1-Voutn and an output capacitor C1-Cn. n is 2 or more. The first transfer switch PM0 may also be referred to as a power switch tube PM0, and the second transfer switch NM0 may be referred to as a rectifying switch tube NM0.

The voltage acquisition module 120 includes a plurality of voltage dividing circuits connected between the branch output terminals Vout1-Voutn of the respective output branches and a ground terminal. Each voltage dividing circuit comprises a first voltage dividing resistor RFB1a-RFBna and a second voltage dividing resistor RFB2b-RFBnb, and the intermediate node of the first voltage dividing resistor RFB1a-RFBna and the intermediate node of the second voltage dividing resistor RFB2b-RFBnb acquire feedback voltages FB1-FBn of each output branch.

The voltage detection module 130 performs hysteresis comparison on the feedback voltages FB1-FBn of each output branch to the corresponding reference voltages Vref1-Vref2 to determine whether the overvoltage protection signal OVP (Over Voltage Protection) of each output branch is valid, e.g., valid high and invalid low. When the overvoltage protection signal OVP of one output branch is valid, it indicates that the output voltage of this output branch has reached the design requirement, and does not need to be charged, wherein the failure of the overvoltage protection signal OVP indicates that the output voltage of this output branch has not reached the design requirement, and needs to be charged. Each of the comparators CMP1-CMPn in the voltage detection module 130 performs a hysteresis comparison, each of the reference voltages Vref1-Vrefn actually includes two sub-reference voltages, and the sub-reference voltage when the over-voltage protection signal OVP is turned from low level to high level is higher than the sub-reference voltage when the over-voltage protection signal OVP is turned from high level to low level, which is related to the prior art, and will not be repeated here.

The logic control module 140 samples the overvoltage protection signals OVP1-n output by the voltage detection module, and the state machine round robin mechanism charges each output branch. When the overvoltage protection signal OVP of one output branch IS inactive, the logic control module 140 drives the first switch PM0 to be turned on through the driving signal PDRV and the driving signal NDRV, the second switch NM0 IS turned off, and the peak detection switch IS1 in the overcurrent protection module 150 and one branch switch Si (i=1, 2 … n) of the output branch to be charged are turned on.

At this time, the inductor L1 increases in current, the overcurrent protection module 150 detects the inductor current through the voltage of the intermediate node SW1, and when the inductor current is greater than the set peak current threshold, the overcurrent protection module 150 outputs an effective (e.g., low-level pulse effective) overcurrent protection signal OCP and sends the signal to the logic control module 140. The logic control module 140 turns off the first transfer switch PM0 by the driving signal PDRV and the driving signal NDRV signal, and turns on the second transfer switch NM0 and turns off the peak detection switch IS 1. The inductor IS converted from a charging state to a discharging state, i.e. the current of the inductor gradually decreases, the valley detection switch IS2 in the reverse current protection module 160 IS turned on, and when the current of the inductor IS smaller than the set valley current threshold, the reverse current protection module 160 outputs a valid (e.g. high level pulse valid) reverse current protection signal RCP. If no other output branch needs to be charged, the logic control module 140 controls the first switch PM0 to be turned off, and the second switch NM0 to be turned off. If there are other output branches to be charged, the state machine round-robin mechanism repeats the above-described charging process. It should be noted that at the same time, only one output branch can be charged through the inductor, and multiple output branches cannot be charged simultaneously. That is, when one of the branch switches is on, the other branch switch needs to be off.

Fig. 2 is a schematic circuit diagram of a single-inductor multiple-output dc-dc converter 200 according to the present invention. As shown in fig. 2, the single-inductor multi-output dc-dc converter 200 includes a conversion circuit 210, a voltage acquisition module 220, a voltage detection module 230, a logic control module 240, an overcurrent protection module 250, and a reverse current protection module 260. The switching circuit 210 includes a first switch PM0 and a second switch NM0 connected between the input power supply terminal VDD and the ground terminal, an inductance L1 connected between the intermediate nodes SW1 (connection nodes of the first switch PM0 and the second switch NM 0) and SW2, and n output branches connected to the intermediate node SW 2. Each output branch (which may be referred to as a branch) includes a branch switch M1-Mn, a branch output Vout1-Voutn, and an output capacitor C1-Cn. n is 2 or more. The first transfer switch PM0 may also be referred to as a power switch tube PM0, and the second transfer switch NM0 may be referred to as a rectifying switch tube NM0. The voltage acquisition module 220 may refer to the voltage acquisition module 120 in fig. 1, and will not be described herein. In addition, other parts that are identical to those of the single-inductor multiple-output dc-dc converter 100 of fig. 1 are not repeated here.

The single-inductor multiple-output dc-dc converter 200 of the present invention is an improvement over the conventional single-inductor multiple-output dc-dc converter 100. 1) The present invention improves the voltage detection circuit 230, which can output not only the overvoltage protection signals OVP1-OVPn of each output branch, but also the voltage too low protection signals vout_low1-vout_low of each output branch. The voltage of each output branch is too low by the active (e.g., active low, inactive high) protection signal vout_low1-vout_lown indicating that the voltage of the output branch is too low, e.g., vout_low1 is active indicating that the voltage at the output of the branch Vout1 is too low. 2) An instant switching module 270 is added that can immediately control the on-state of the leg switch of one output leg when the voltage-down signal of that output leg is active, and the off-state of the leg switches of the other output legs to immediately charge that output leg without waiting. Therefore, the problem that when the load current of one output branch is jumped from light load to heavy load, the system cannot be timely switched to the output branch for charging, so that larger undershoot voltage is generated can be solved. 3) A reverse current protection adaptive module 280 is added, which outputs an actual reverse current protection signal rcp_true that is active (e.g., high pulse is active) when the inductor discharges and one of the reverse current protection signal RCP and any of the low voltage signals vout_low1-vout_low is active, and the logic control module 240 controls the transfer switch assembly to stop discharging the inductor when the actual reverse current protection signal rcp_true is active. Therefore, the valley current threshold value of the inductor can be selected in a self-adaptive mode, when the voltage of any output branch is too low, the inductor discharge of the current output branch can be stopped immediately, the inductor charge of the next output branch is started, the next output branch is charged rapidly, and the initial power supplied to the next output branch is higher. 4) The over-current adaptive module 290 is added, when the inductor is charged and one of the over-current protection signal and the over-voltage protection signal of the currently charged output branch is valid, the logic control module 240 outputs an effective (such as a low-level pulse is effective) actual over-current protection signal ocp_tune, and when the actual over-current protection signal ocp_tune is effective, the logic control module controls the change-over switch combination to stop the charging of the inductor L1 by the input power supply terminal VDD. Therefore, the peak current threshold value of the inductor can be selected in a self-adaptive mode, the problems that the peak current threshold value of the inductor is difficult to set and the light load output voltage ripple is large are solved, the peak current of the inductor can be matched with loads in all paths of output branches better, and the conversion efficiency of the DC-DC power supply is further improved.

It should be noted that in some embodiments, the single-inductor multiple-output dc-dc converter 200 of the present invention may be modified in only one or more of the four aspects described above, rather than all including the four aspects described above. For example, in some embodiments, only the improvements of the first aspect and the second aspect may be included, only the improvements of the first aspect and the third aspect may be included, only the improvements of the first aspect, the second aspect and the third aspect may be included, only the improvements of the fourth aspect may be included, and the improvements of the fourth aspect may be combined with other improvements. Modifications in various respects will be described in detail below.

As shown in fig. 2, the voltage detection circuit 230 determines whether the overvoltage protection signal OVP1-OVPn of each output branch is valid according to the feedback voltage FB1-FBn of each output branch, and also determines whether the voltage too low signal vout_low1-vout_low of each output branch is valid according to the feedback voltage FB1-FBn of each output branch. The overvoltage protection signals OVP1-OVPn of each output branch are valid, indicating that the output branch does not need to be charged, and the overvoltage protection signals OVP1-OVPn of each output branch are invalid, indicating that the output branch needs to be charged. The voltage-too-low signal vout_low1-vout_low of each output branch is active to indicate that the voltage of that output branch is too low, and the voltage-too-low signal vout_low1-vout_low of each output branch is inactive to indicate that the voltage of that output branch is not too low. For example, OVP1 is inactive (active high, inactive low), indicating that the first output branch needs to be charged, and OVP1 is active, indicating that the first output branch does not need to be charged. For another example, vout_low1 is inactive (active low, inactive high), indicating that the voltage of the first output branch is not too low, and vout_low1 is active, indicating that the voltage of the first output branch is too low.

More specifically, the voltage detection circuit 230 compares the feedback voltage FB1-FBn of each output branch with the corresponding first reference voltage Verf1-Verfn to obtain a first comparison result, and determines whether the overvoltage protection signal OVP1-OVPn of each output branch is valid according to the first comparison result. The overvoltage protection signals OVP1-OVPn of each output branch are active when the feedback voltage of that output branch is greater than or equal to the corresponding first reference voltage Verf 1-Verfn. In fact, as mentioned above, the first comparison result is a comparison result of the hysteresis comparison, the first reference voltages Verf1-Verfn of each output branch comprise two sub-reference voltages forming a group, and the sub-reference voltages effectively corresponding to the over-voltage protection signals OVP1-OVPn from the inactive transitions are higher than the sub-reference voltages effectively corresponding to the over-voltage protection signals OVP1-OVPn from the active transitions to the inactive transitions, which will not be described in detail herein. That is, the overvoltage protection signals OVP1-OVPn are changed from inactive to active only when the feedback voltages FB1-FBn are greater than the greater of the two sub-reference voltages, and from active to inactive only when the feedback voltages FB1-FBn are less than the smaller of the two sub-reference voltages.

The voltage detection circuit 230 further compares the feedback voltage FB1-FBn of each output branch with the corresponding second reference voltage verf1_2-verfn_2 to obtain a second comparison result, and determines whether the voltage too low signal vout_low1-vout_low of each output branch is valid according to the second comparison result. For example, the voltage-undershoot signal vout_low1-vout_lown of each output branch is active when the feedback voltage of the output branch is less than the corresponding second reference voltage verf1_2-verfn_2, and the voltage-undershoot signal vout_low1-vout_lown of each output branch is inactive when the feedback voltage of the output branch is greater than the corresponding second reference voltage verf1_2-verfn_2. In another example, the second comparison result may also be a comparison result of a hysteresis comparison, i.e. the second reference voltage verf1_2-verfn_2 of each output branch comprises two sub-reference voltages, which form a group. The sub-reference voltage effectively corresponding to the voltage over-low signal Vout_low1-Vout_low of the output branch from the inactive jump is lower than the sub-reference voltage effectively corresponding to the inactive jump. That is, the feedback voltages FB1-FBn are lower than the smaller sub-reference voltage of the two sub-reference voltages, the voltage-too-low signal Vout_Low1-Vout_Low changes from inactive to active, and the feedback voltages FB1-FBn are higher than the larger sub-reference voltage of the two sub-reference voltages, the voltage-too-low signal Vout_Low changes from active to inactive.

In one embodiment, the instant switching module 270 immediately controls the on-state of the branch switch Mi of one output branch i when the voltage too low signal vout_low of the output branch i is active, and the off-state of the branch switches Mi of other output branches to immediately charge the output branch Vouti, wherein i is greater than or equal to 1 and less than or equal to n.

Normally, the logic control module 240 sequentially controls the on of the branch switches of the output branches for which the overvoltage protection signal is invalid through the state machine round robin mechanism, so as to charge the output branches for which the overvoltage protection signal is invalid. As mentioned above, only one output branch can be charged at a time. The logic control module 140 outputs a corresponding bypass switch control signal S1-Sn for each bypass switch M1-Mn.

The instant switching module 270 receives each of the branch switch control signals S1-Sn and the voltage-too-low signal vout_low1-vout_low of each of the output branches, and when the voltage-too-low signal vout_low1-vout_low of each of the output branches is invalid, outputs each of the branch switch control signals S1-Sn outputted by the logic control module 270 directly as an actual branch switch control signal s1_tune-sn_tune of each of the branch switches to control each of the branch switches M1-Mn. When the voltage too low signal vout_low of one output branch is valid, the instant switching module 270 outputs the actual branch switch control signal s1_tune-sn_tune of each output branch according to each branch switch control signal S1-Sn and the voltage too low signal vout_low of each output branch, so that the actual branch switch control signal si_tune corresponding to the output branch Vouti with the voltage too low signal is valid can immediately control the corresponding branch switch Mi to be turned on, and the other actual branch switch control signals control the branch switches of other output branches to be turned off.

Fig. 6 is a schematic circuit diagram of the instant switch module 270 in fig. 2 in one embodiment. It is apparent that other embodiments of the instant switch module 270 exist. As shown in fig. 6, the instant switching module 270 includes n instant switching units, each of which includes a first logic unit 271, a first gate 272, a second gate 273, a first nand gate 274, and a second nand gate 275.

The first logic unit 271 includes a first inverter and a second inverter connected in series, the input ends of the first inverters of the n instant switching units respectively receive the excessively low voltage signals vout_low1-vout_low of the corresponding output branches, the output ends of the first inverters of the n instant switching units respectively output the second signals DSYNB1, DSYNB2, …, DSYNBn, the input ends of the second inverters are connected with the output ends of the first inverters, and the output ends of the second inverters of the n instant switching units respectively output the first signal signals DSYN1, DSYN2, …, DSYNn. The first input terminals of the first gates 272 of the n instant switching units are respectively connected to the branch switch control signals S1, S2, …, sn of the corresponding output branches, the second input terminals are grounded, the output terminals are connected to the second input terminal of the second gate 273, and the first input terminal of the second gate 273 is connected to the power supply VDD. The first signals DSYN1, DSYN2, …, DSYNn are connected to a plurality of input terminals of the first nand gate 274 of each instant switching unit, and an output terminal of the first nand gate 274 is connected to the Set terminal Set of the first gate. One of the plurality of input ends of the second nand gate 275 of each instant switching unit i is connected to the second signal DSYNBi corresponding to the cueing switching unit i, the other input end of the second nand gate of each instant switching unit i is connected to the other first signal DSYN except the first signal DSYNi, and the output end of the second nand gate is connected to the Set end Set of the second gate. The signal output of the first input terminal a is selected when the Set of each gate 272, 273 is low and the signal output of the second input terminal B is selected when the Set of each gate is high. The output ends of the second gates of the n instant switching units respectively output actual branch switch control signals s1_true, s2_true, … and sn_true of the corresponding output branches.

When the voltage of the output branches is too low, vout_low1, vout_low2, …, vout_lown are high, DSYN1, DSYN2, …, DSYN3 are high, the Set end of the first gate is low, the outputs of the first gate are S1, S2, …, sn, and DSYNB1 are low, so the Set end of the second gate is high, s1_tune-sn_tune is the same as S1-Sn, and the output branches are charged by the state machine round-robin mechanism (i.e., the output branches to be charged are sequentially charged). When the voltage of the first output branch is too low, vout_low1 is low, DSYN1 is low, DSYNB1 is high, and the output signal s1_true of the second gate is high, which is similar to the above analysis, so that the branch switch M1 is turned on, and the rest branch switches are turned off, thereby realizing instant switching to the output branch for charging, achieving the purpose of fast load transient response, and reducing the undershoot voltage Δvundershoot1. When vout_low2 is active, s2_true is high. When vout_low is active, sn_true is high.

In one embodiment, the reverse current protection adaptive module 280 outputs an active (high pulse active) actual reverse current protection signal rcp_true when the inductor discharges and one of the reverse current protection signal RCP and any of the low voltage signals vout_low1-vout_low is active, otherwise outputs an inactive actual reverse current protection signal rcp_true. The logic control module 240 controls the second transfer switch NM0 to be turned off to stop discharging the inductor L1 when the actual reverse current protection signal rcp_true is active. Therefore, the valley current threshold value of the inductor can be selected in a self-adaptive mode, when the voltage of any output branch is too low, the inductor discharge of the current output branch can be stopped immediately, the inductor charge of the next output branch is started, the next output branch is charged rapidly, and the initial power supplied to the next output branch is higher.

Fig. 7 is a schematic circuit diagram of the reverse current protection adaptive module 280 in fig. 2 in one embodiment. As shown in fig. 7, the reverse current protection adaptation module includes a second logic unit 281 and a third logic unit 282. The input terminal of the second logic unit 281 receives the voltage-too-low signal vout_low1-vout_low of each output branch, and when any one of the voltage-too-low signals vout_low1-vout_low of the output branches is valid, the second logic unit 281 outputs a valid logic signal, otherwise, outputs an invalid logic signal. The first input terminal of the third logic unit 282 is connected to the output terminal of the second logic unit 281, the second input terminal of the third logic unit 282 receives the reverse current protection signal RCP, when one of the logic signal and the reverse current protection signal outputted from the second logic unit 281 is valid, the third logic unit 282 outputs a valid actual reverse current protection signal rcp_true, otherwise, outputs an invalid actual reverse current protection signal rcp_true.

As shown in fig. 7, the second logic unit 281 includes a third nand gate 2811, a high level pulse generator 2812. The multiple input ends of the third NAND gate respectively receive the voltage too low signals Vout_low1-Vout_low of each output branch, and the output end of the third NAND gate is connected with the input end of the high-level pulse generator 2812, and the output end of the high-level pulse generator is the output end of the second logic unit 281. The third logic unit 282 includes an or gate.

In fig. 7, the high-level pulse signal generated by the excessively low voltage signal vout_low1-vout_low is logically or-ed with the reverse current protection signal RCP, so that when the trigger voltage of the output branch is excessively low vout_low before the trigger RCP is effective, the inductor discharge can be terminated in advance, and the next output branch can be charged immediately. The high-level pulse generator is a circuit for generating a high-level pulse signal according to a rising edge signal. When the inductor L1 discharges, the driving signal PDRV is at a high level, the power switch PM0 is turned off, the driving signal NDRV signal is at a low level, the rectifying switch NM0 is turned on, if the output voltage of the output branch is too high, the excessively low voltage signal vout_low generated by the output branch is at a low level (valid), a rising edge is provided to the high level pulse generator 2812 through the third nand gate 2811, the high level pulse generator outputs a high level pulse signal, the high level pulse signal and the actual reverse current protection signal rcp_true generated after the reverse current protection signal RCP are also high level pulse signals, the logic control module 240 makes the driving signal PDRV at a low level, the power switch PM0 is turned on, the driving signal NDRV signal is at a high level, the rectifying switch NM0 is turned off, the inductor discharge of the current output branch is stopped, and the inductor charge of the next output branch is started, so that the inductor charge of the next output branch is rapidly charged.

In one embodiment, the over-current adaptive module 290 outputs an active (e.g., low-level pulse active) actual over-current protection signal ocp_tune when the inductor is charged and one of the over-current protection signal OCP and the over-voltage protection signal OVP of the currently charged output branch is active, and otherwise outputs an inactive actual over-current protection signal ocp_tune. When the actual over-current protection signal ocp_tune is active, the logic control module 240 controls the first switch PM0 to be turned off and the second switch NM0 to be turned on, and the input power terminal VDD stops charging the inductor L1. Therefore, the peak current threshold value of the inductor can be selected in a self-adaptive mode, the problems that the peak current threshold value of the inductor is difficult to set and the light load output voltage ripple is large are solved, the peak current of the inductor can be matched with loads in all paths of output branches better, and the conversion efficiency of the DC-DC power supply is further improved.

Fig. 8 is a schematic circuit diagram of the overcurrent protection adaptive module 290 in fig. 2 in one embodiment. As shown in fig. 8, the overcurrent protection adaptation module 290 includes a third gating unit, a fourth logic unit 291, and a fourth gating unit 292. The third gating unit selects and outputs the overvoltage protection signal OVP of the currently charged output branch from among the overvoltage protection signals OVP1-OVPn of the respective output branches. The first input terminal of the fourth logic unit 291 is connected to the output terminal of the third gating unit to receive the over-voltage protection signal OVP of the output branch currently being charged, and the second input terminal of the fourth logic unit 291 is connected to the output terminal of the over-current protection module 250 to receive the over-current protection signal OCP. The fourth logic unit 291 outputs an active (e.g., low-level pulse active) over/over-current protection signal ovp_ocp when one of the over-current protection signal OVP and the over-current protection signal OCP (e.g., low-level pulse active) of the currently charged output branch is active, and outputs an inactive over-current/over-current protection signal otherwise. The first input terminal a of the fourth gating unit 292 is connected to the output terminal of the fourth logic unit 291 to receive the over-voltage/over-current protection signal, and the second input terminal B of the fourth gating unit 292 is connected to the output terminal of the over-current protection module to receive the over-current protection signal.

The SET end SET of the fourth gate unit 292 is connected to the driving signal NDRV. The fourth gating unit 292 selects the over-voltage/over-current protection signal received at the first input terminal as an actual over-current protection signal and outputs the over-voltage/over-current protection signal when the inductor is charged, and selects the over-current protection signal received at the second input terminal as an actual over-current protection signal and outputs the over-current protection signal when the inductor is not charged.

The overvoltage protection signal OVP is active high and the overcurrent protection signal is active low. The fourth logic unit 291 includes a low-level pulser, a nand gate, and an inverter, the input terminal of the low-level pulser is a first input terminal of the fourth logic unit 291, the output terminal of the low-level pulser is connected to one input terminal of the nand gate, the other input terminal of the nand gate is a second input terminal of the fourth logic unit, the output terminal of the nand gate is connected to the input terminal of the inverter, the output terminal of the inverter is an output terminal of the fourth logic unit, and the Set terminal Set of the fourth gate 291 is connected to the driving signal NDRV of the second transfer switch.

And generating a low-level pulse signal after the overvoltage protection signal OVP of the currently charged output branch is changed to a high level, and replacing the low-level pulse signal of the overcurrent protection signal OCP. The fourth gating unit 291 is a one-out-of-two module, and selects B when the Set terminal Set is high and selects a when the Set terminal Set is low. In a specific operation process, the overvoltage protection signal OVP of the currently charged output branch circuit generates a low level pulse after becoming high level, and the overcurrent protection signal OCP is logically and, when the inductor L1 is charged, the driving signal NDRV is low level, the fourth gating unit 291 selects a, if the signal OVP is first turned to high level, the signal ovp_ocp will generate a falling edge pulse when the signal OVP is turned to high level, meanwhile, the ocp_true will stop charging and start discharging the inductor, if the signal OVP does not become high level before the falling edge pulse of the OCP is generated or is turned to high level during the discharging process of the inductor, the falling edge pulse of the signal OCP is still used.

Fig. 3 is a schematic diagram illustrating the operation of the single-inductor multi-output dc-dc converter 200 according to the present invention.

In step 301, the overvoltage protection signal OVPi is low (invalid), which indicates that the ith branch needs to be charged, and the logic control module 240 controls the power switch PM0 to be turned on, and the rectifying switch NM0 to be turned off, so as to start charging the inductor L1.

In step 302, during charging of the inductor L1, it is determined whether the overvoltage protection signal OVPi is inverted to a high level (active). If yes, step 303 is entered, and if no, step 304 is entered.

In step 303, the actual over-current protection signal ocp_true is a low-level pulse signal (valid), the logic control module 240 controls the power switch tube PM0 to be turned off, the rectifying switch tube NM0 to be turned on, the inductor L1 stops charging, and the process proceeds to step 305 to perform the inductive discharge.

In step 304, the inductor current reaches the peak current threshold, the over-current protection signal OCP generates a low-level pulse signal (valid), the actual over-current protection signal ocp_true is the low-level pulse signal (valid), the logic control module 240 controls the power switch tube PM0 to be turned off, the rectifying switch tube NM0 to be turned on, the inductor L1 stops charging, and the process proceeds to step 305 to perform the inductor discharging.

Step 307 is then entered, at which time the logic control module 240 charges the branches that need to be charged according to the state machine round robin mechanism.

After step 301, step 306 is concurrently entered to confirm whether the voltage-too-low signal vout_low1-vout_low of each branch is low (active). If not, step 307 is entered. If so, the branch is deemed to enter a voltage too low state (triggering Vout_Low state), and step 308 is entered.

Step 308, it is determined whether the inductor L1 is discharged at the time. If yes, step 309 is entered, where the actual reverse current protection signal rcp_true generates a high level pulse, the logic control module 240 controls the power switch PM0 to be turned on, the rectifying switch NM0 to be turned off, and stops discharging the inductor L1, and the instant switching module 270 immediately controls the voltage too low signal to be the active corresponding branch switch to be turned on, and other branch switches to be turned off, so as to charge the branch.

In step 310, the current charging process is interrupted, and the instant switching module 270 immediately controls the voltage too low signal to be turned on for the corresponding branch switch, and the other branch switches are turned off to charge the branch.

Step 311, it is determined whether the branch exits the state of too low a voltage, and if so, in step 312, the state machine round robin mechanism is switched to charge, or other branches for which too low a voltage is active are switched to charge.

If not, in step 313, it is determined whether there are more than two branches triggering the state of too low a voltage, and if so, step 314 is entered, and the branches entering the state of too low a voltage are cycled. If not, the branch entering the overvoltage state is continuously charged.

It should be noted that the above procedure is described for convenience in describing the single-inductor multiple-output dc-dc converter 200 of the present invention, and is not meant to be operated in a single step.

Fig. 4 is a graph showing the output condition when the load is changed in the conventional multi-path round robin charging control method, and fig. 5 is a graph showing the output condition when the load is changed after the optimization.

As shown in fig. 4, t1, t2, t3, and t4 are each time, OVP1 is low at t1, indicating that the first branch needs to be charged, OVP2 is low at t2, indicating that the second branch needs to be charged, and if the load of the I-th branch changes from I0 to I1 suddenly at t5, OVPi becomes low at t3, and the I-th branch needs to be charged; if the load current of the ith branch is constant at I0, the OVPi becomes low level at the time t4, and the ith branch needs to be charged. It can be seen that according to the conventional multi-path round robin charging control manner, the charging sequence of each branch is the 1 st branch, the 2 nd branch and the I th branch, although at the time t5, the load current Iloadi of the I th branch jumps from I0 to I1, the speed of the output voltage Vouti undershoot of the I th branch also becomes fast, vundershoot1 is the I th branch undershoot voltage at this time, and the theoretical maximum output undershoot voltage is: delta Vundershorthi=Iload (i-1) T/Cload, which in severe cases can cause instability of the output voltage of the DC-DC converter, compromising the stability of the powered system.

As shown in fig. 5, before time t2, OVP1 is turned from low level to high level, ocp_true generated by the over-current adaptive module 290 is a new low level pulse signal, the logic control module 240 controls the inductor L1 to stop charging and start discharging, time t2, OVP2 is turned to low level, at time t3, the voltage detection module detects that the OVPi of the ith branch is turned to low level, since the load current jumps from I0 to I1 at time t5, the undershoot speed of the output voltage Vouti of the ith branch becomes fast, the voltage detection module 230 detects that the output voltage of the ith branch is smaller than the set reference voltage at time t6, the voltage over-low signal vout_low output by the voltage detection module 230 is turned to low level, and is fed into the reverse current protection adaptive module and the instant switching module, the rcp_tune output by the reverse current protection adaptive module is a high level pulse signal, the inductor is stopped discharging to the first branch, and starts to charge the inductor, at the same time, the instant switching module makes Si_TRUE become high level, the branch switch Mi of the ith branch is conducted, instant switching to the ith branch is realized to charge the ith branch, the output voltage Vouti of the ith branch starts to rise at t6, at t7, the output voltage of the ith branch is larger than the set reference voltage, the Vout_low signal is turned to high level, at this moment, si_TRUE output by the instant switching module is low level, the branch switch Mi is turned off, the branch switch M2 is conducted according to the branch switch S2 generated by the state machine round-robin mechanism in the control logic module 240 is high level, the instant switching module 270 outputs S2_TRUE to high level, the branch switch M2 is conducted, and charging is continued for the 2 nd branch, so that under the condition of balancing the output voltages of other branches, the fast load transient response is achieved, the undershoot voltage delta V undershort 1 is reduced to delta V undershort 2, the magnitude of the output voltage ripple of each branch is reduced.

Aiming at the defects of the traditional peak current control mode and the energy distribution mode of state machine round robin charging in the background, the invention provides a single-inductor multi-output direct current-direct current converter with the self-adaptive and quick response of the peak-valley current threshold value of the inductive current, which not only can keep the advantages of the peak current control mode, but also can realize the output voltage with low ripple, and simultaneously can more flexibly and rapidly process the energy distribution of each output branch when facing to the changed load current.

According to the invention, an inductive current peak-valley threshold self-adaptive mode is adopted in combination with output voltage hysteresis control, an inductive current peak value capable of meeting the maximum requirement of each branch load is set according to the load condition of each output branch, meanwhile, inductive current and output voltage are detected, and when judging conditions are met, the power switch tube is conducted and closed, so that overshoot voltage is reduced. When a load of a certain branch is jumped from light load to heavy load, the electricity consumption of the branch is increased, the descending speed of the output voltage of the branch is increased, and when the output voltage of the branch triggers a set threshold value, the branch is immediately switched to charge, so that the undershoot voltage is reduced, and the serious voltage power failure problem is avoided. And if the output voltages of the multiple branches trigger the set threshold value at the same time, the charge is cycled in the output branch which triggers the set threshold value. The energy distribution of each output branch is flexibly and rapidly processed, the upper punch and lower punch voltages of each output branch are reduced, the quick response of load transient change is realized, the ripple wave of the output voltage is reduced, and the system stability is improved.

In the present invention, "connected," "coupled," and the like, refer to electrical connection, either direct or indirect, unless otherwise indicated.

It should be noted that any modifications to the specific embodiments of the invention may be made by those skilled in the art without departing from the scope of the invention as defined in the appended claims. Accordingly, the scope of the claims of the present invention is not limited to the foregoing detailed description.

Claims (12)

1. A single inductor multiple output dc-dc converter comprising:

the switching circuit comprises an input power supply end, a switching assembly, an inductor and at least two output branches, wherein each output branch comprises a branch output end and a branch switch;

the voltage detection circuit is configured to determine whether an overvoltage protection signal of each output branch is effective according to the feedback voltage of each output branch, wherein the overvoltage protection signal of each output branch effectively indicates that the output branch does not need to be charged, the overvoltage protection signal of each output branch is invalid to indicate that the output branch needs to be charged, the voltage of each output branch effectively indicates that the voltage of the output branch is too low, and the voltage of each output branch is not too low;

A logic control module configured to control the transfer switch assembly such that the inductor is charged or discharged;

and the instant switching module is configured to immediately control the on state of the branch switch of one output branch and the off state of the branch switch of other output branches when the voltage too low signal of the output branch is valid so as to immediately charge the output branch.

2. The single inductor multiple output dc-dc converter of claim 1 wherein,

the voltage detection circuit compares the feedback voltage of each output branch with a corresponding first reference voltage to obtain a first comparison result, determines whether the overvoltage protection signal of each output branch is effective according to the first comparison result,

and comparing the feedback voltage of each output branch with a corresponding second reference voltage to obtain a second comparison result, and determining whether the voltage too low signal of each output branch is effective or not according to the second comparison result.

3. The single-inductor multiple-output DC-DC converter of claim 1 wherein said logic control module sequentially controls the conduction of the branch switches of each output branch for which the overvoltage protection signal is inactive via a round robin mechanism,

Each branch switch is controlled such that the inductor can charge only one output branch at a time,

the single-inductor multi-output direct current-direct current converter further comprises a voltage acquisition module, wherein the voltage acquisition module is used for acquiring the voltage of the output end of each branch to obtain the feedback voltage of each output branch.

4. The single inductor multiple output dc-dc converter of claim 1 wherein,

the logic control module outputs a corresponding branch switch control signal for each branch switch,

the instant switching module receives the control signals of each branch switch and the low voltage signals of each output branch, and when the low voltage signals of each output branch are invalid, the control signals of each branch switch output by the logic control module are directly output as actual branch switch control signals to control each branch switch;

when the voltage of one output branch is effective, the instant switching module outputs an actual branch switch control signal of each output branch according to each branch switch control signal and the voltage of each output branch, so that the actual branch switch control signal corresponding to the output branch with the effective voltage of the voltage is capable of immediately controlling the corresponding branch switch to be conducted, and other actual branch switch control signals control the branch switches of other output branches to be disconnected.

5. The single inductor multiple output dc-dc converter of claim 4 wherein,

the instant switching module comprises n instant switching units, each instant switching unit comprises a first logic unit, a first gating device, a second gating device, a first NAND gate and a second NAND gate,

the first logic unit comprises a first inverter and a second inverter which are connected in series, the input ends of the first inverters of the n instant switching units respectively receive the excessively low voltage signals of the corresponding output branches, the output ends of the first inverters of the n instant switching units respectively output second signals DSYNB1, DSYNB2, … and DSYNB, the input ends of the second inverters are connected with the output ends of the first inverters, the output ends of the second inverters of the n instant switching units respectively output first signals DSYN1, DSYN2, … and DSYNN, n are the number of the output branches,

the first input end of the first gate of the n instant switching units is connected with branch switch control signals S1, S2, … and Sn of corresponding output branches respectively, the second input end is connected with the ground, the output end is connected with the second input end of the second gate, the first input end of the second gate is connected with the power supply VDD,

The first signals DSYN1, DSYN2, … and DSYNN are all connected to a plurality of input ends of a first NAND gate of each instant switching unit, the output end of the first NAND gate is connected with the setting end of a first gating device, one of a plurality of input ends of a second NAND gate of each instant switching unit i is connected with a second signal DSYNBI corresponding to the queue switching unit i, the other input ends of the second NAND gate of each instant switching unit i are connected with other first signals except the first signal DSYNI, the output end of the second NAND gate is connected with the setting end of the second gating device, i is more than or equal to 1 and less than or equal to n,

the signal output of the first input terminal is selected when the set terminal of each gate is at a low level, the signal output of the second input terminal is selected when the set terminal of each gate is at a high level,

the output ends of the second gates of the n instant switching units respectively output actual branch switch control signals s1_true, s2_true, … and sn_true of the corresponding output branches.

6. The single-inductor, multiple-output dc-dc converter of claim 1, further comprising:

the reverse current protection module is configured to detect the current of the inductor, output an effective reverse current protection signal when the inductor current is smaller than or equal to a valley current threshold value, and output an ineffective reverse current protection signal otherwise;

A reverse current protection adaptive module configured to output a valid actual reverse current protection signal when the inductor discharges and one of the reverse current protection signal and any undervoltage signal is valid, and otherwise, output an invalid actual reverse current protection signal,

and the logic control module controls the transfer switch assembly to stop discharging the inductor when the actual reverse current protection signal is effective.

7. The single inductor multiple output dc-dc converter of claim 6 wherein,

the reverse current protection adaptive module comprises a second logic unit and a third logic unit,

the input end of the second logic unit receives the voltage too low signal of each output branch, and when the voltage too low signal of any output branch is valid, the second logic unit outputs a valid logic signal, otherwise, outputs an invalid logic signal,

the first input end of the third logic unit is connected with the output end of the second logic unit, the second input end of the third logic unit receives the reverse flow protection signal, when one of the logic signal output by the second logic unit and the reverse flow protection signal is effective, an effective actual reverse flow protection signal is output, and otherwise, an ineffective actual reverse flow protection signal is output.

8. The single inductor multiple output dc-dc converter of claim 7 wherein,

the second logic unit comprises a third NAND gate and a high-level pulse generator, wherein a plurality of input ends of the third NAND gate respectively receive the low-voltage signals of each output branch, the output end of the third NAND gate is connected with the input end of the high-level pulse generator, the output end of the high-level pulse generator is the output end of the second logic unit,

the third logic unit includes an or gate.

9. The single inductor multiple output dc-dc converter of claim 1 wherein,

the overcurrent self-adapting module is configured to output an effective actual overcurrent protection signal when the inductor is charged and one of the overcurrent protection signal and the overvoltage protection signal of the currently charged output branch is effective, otherwise, output an ineffective actual overcurrent protection signal,

and the logic control module is configured to control the change-over switch combination to stop the input power supply end from charging the inductor when the actual overcurrent protection signal is effective.

10. The single inductor multiple output dc-dc converter of claim 9 wherein,

The overcurrent protection self-adaptive module comprises a third gating unit, a fourth logic unit and a fourth gating unit,

the third gating unit selects and outputs the overvoltage protection signal of the currently charged output branch from the overvoltage protection signals of the respective output branches,

the first input end of the fourth logic unit is connected with the output end of the third gating unit to receive the overvoltage protection signal of the output branch which is currently charged, the second input end of the fourth logic unit is connected with the output end of the overcurrent protection module to receive the overcurrent protection signal,

the fourth logic unit outputs a valid overvoltage/overcurrent protection signal when one of the overvoltage protection signal and the overcurrent protection signal of the currently charged output branch is valid, otherwise outputs an invalid overvoltage/overcurrent protection signal,

the first input end of the fourth gating unit is connected with the output end of the fourth logic unit to receive the overvoltage/overcurrent protection signal, the second input end of the fourth gating unit is connected with the output end of the overcurrent protection module to receive the overcurrent protection signal,

the fourth gating unit selects the overvoltage/overcurrent protection signal received by the first input end as an actual overcurrent protection signal and outputs the overvoltage/overcurrent protection signal when the inductor is charged, and selects the overcurrent protection signal received by the second input end as an actual overcurrent protection signal and outputs the overcurrent protection signal when the inductor is not charged.

11. The single inductor multiple output dc-dc converter of claim 10 wherein,

the overvoltage protection signal is active high, the overcurrent protection signal is active low,

the fourth logic unit comprises a low-level pulser, a NAND gate and an inverter, wherein the input end of the low-level pulser is used as the first input end of the fourth logic unit, the output end of the low-level pulser is connected with one input end of the NAND gate, the other input end of the NAND gate is used as the second input end of the fourth logic unit, the output end of the NAND gate is connected with the input end of the inverter, the output end of the inverter is used as the output end of the fourth logic unit,

and the setting end of the fourth gating unit is connected with a driving signal of a second change-over switch in the change-over switch assembly.

12. The single inductor multiple output dc-dc converter of claim 1 wherein,

the transfer switch assembly includes: a first transfer switch connected between the input power source terminal and the intermediate node SW1 and a second transfer switch connected between the intermediate node SW1 and the ground terminal; the inductance is connected between the intermediate node SW1 and the intermediate node SW2,

The input of each output branch is connected to an intermediate node SW2,

the reverse current protection module is used for comparing the voltage of the intermediate node SW1 with a valley current threshold value and outputting a reverse current protection signal according to a comparison result;

the overcurrent protection module is used for acquiring the voltage of the intermediate node SW1, comparing the voltage with a peak current threshold value, outputting an overcurrent protection signal according to the comparison result,

each output branch comprises: an output capacitor connected between the branch output terminal and the ground terminal;

when the overvoltage protection signal of at least one output branch is invalid, the logic control module controls the first transfer switch to be turned on, the second transfer switch to be turned off, at the moment, the input power supply end starts to charge the inductor, the inductor current is gradually increased, the logic control module controls the branch switch of the output branch, of which the overvoltage protection signal is invalid, to be turned on, and the inductor charges the output branch, which is turned on by the branch switch;

when the actual overcurrent protection signal is effective, the logic control module controls the first transfer switch to be turned off, the second transfer switch to be turned on, at the moment, the input power supply end stops charging the inductor, the inductor is discharged, and the inductor current is gradually reduced;

And when the actual reverse current protection signal is valid, the logic control module controls the second transfer switch to be turned off.