Step-down conversion circuit based on double-loop control digital linear voltage stabilization module

Abstract

A step-down conversion circuit based on a double-loop control digital linear voltage stabilization module comprises a pair of off-chip ceramic capacitors, a hybrid topology framework direct-current transformation module located in a high-side voltage domain, and a digital linear voltage stabilization module, an output voltage control loop and an auxiliary control loop which are connected with the hybrid topology framework direct-current transformation module and located in a low-side voltage domain. Energy is efficiently transmitted through the direct current transformation module of the hybrid topology architecture, the output voltage is adjusted through the digital linear voltage stabilization module, a fast transient response is achieved for load abrupt change, and meanwhile the system power density is also improved through the use of the digital linear voltage stabilization module. In addition, the adopted double-loop control ensures that the digital linear voltage stabilization module works in a low dropout condition, and the conversion efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a technology in the field of direct current step-down converters, in particular to a step-down conversion circuit based on a dual-loop controlled digital linear voltage stabilizing module. Background Art

[0002] The DC transformer module of the hybrid topology architecture combines the advantages of the switched capacitor DC transformer module and the inductor DC transformer module, has high power density and high efficiency, and is often used in high conversion ratio occasions. However, the load transient response speed of the DC transformer module of the hybrid topology architecture is usually slow. The digital linear voltage regulator module uses digital control to adjust the output voltage, has high power density and high load transient response speed, and is suitable for low output voltage occasions. However, the efficiency of the digital linear voltage regulator module is determined by the voltage difference between its input voltage and output voltage, and it is difficult to achieve high efficiency. When the DC transformer module of the hybrid topology architecture and the digital linear voltage regulator module are combined in a structure with input series and output parallel, their advantages of high conversion ratio, high power density and high load response speed can be combined. However, how to achieve high efficiency of this architecture under a wide input and output voltage range is also a design difficulty. Summary of the invention

[0003] The present invention aims at the shortcomings of the existing buck converters, which usually have low power density, slow load response speed, and cannot achieve voltage conversion and high-efficiency voltage conversion at high voltage conversion ratios. A buck conversion circuit based on a dual-loop controlled digital linear voltage regulator module is proposed. The DC transformer module of the hybrid topology architecture transmits energy efficiently, and the output voltage is adjusted by the digital linear voltage regulator module. There is a faster transient response to sudden load changes. At the same time, the use of the digital linear voltage regulator module also improves the system power density. In addition, the dual-loop control adopted ensures that the digital linear voltage regulator module works in a low voltage difference condition, thereby improving the conversion efficiency.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to a step-down conversion circuit based on a dual-loop controlled digital linear voltage regulator module, comprising: a pair of off-chip ceramic capacitors, a hybrid topology DC transformer module in a high-side voltage domain, and digital linear voltage regulator modules in a low-side voltage domain respectively connected thereto, an output voltage control loop and an auxiliary control loop, wherein: the off-chip ceramic capacitors and divide the input voltage into a high-side voltage domain and a low-side voltage domain, the output currents of the hybrid topology DC transformer module and the digital linear voltage regulator module are added as the total output current, the output voltage of the hybrid topology DC transformer module is fed back to the digital linear voltage regulator module with a high-frequency clock through the output voltage control loop, the input end of the auxiliary control loop is arranged between a pair of off-chip ceramic capacitors and, and a clock signal is output to the hybrid topology DC transformer module to match the size of regulation, so that the digital linear voltage regulator module works in a low voltage difference condition and achieves a high load response speed.

[0006] The hybrid topology DC transformer module includes: three capacitors, an inductor and a power switch, wherein: the second capacitor and the inductor are arranged in series between the input end and the output end, the first capacitor is arranged between the input end and the ground potential, the third capacitor is arranged between the output end and the ground potential, and power switches are respectively arranged between the input end, the output end and the ground potential and the three capacitors. Through different switch combinations, the connection mode of the inductor, the capacitor and the switch is alternately changed between the two phases. In phase 1, the third, fourth and sixth power switches are closed, the first capacitor charges the second capacitor, the third capacitor discharges, and the inductor is magnetized. In phase 2, the first, second, fifth and seventh power switches, and are closed, the first capacitor is connected between and to charge, the second capacitor charges the third capacitor, and the inductor is demagnetized. Technical Effects

[0007] The present invention adopts a hybrid topology architecture in which a DC transformer module and a digital linear voltage regulator module are connected in series and their outputs are connected in parallel, and an auxiliary control loop is used to adjust the voltage difference of a low-side digital linear voltage regulator module. Compared with the prior art, the present invention is superior to the ordinary DC voltage converter in terms of load mutation transient response speed, and can control the low-side digital linear voltage regulator module to always operate in a low voltage difference mode, thereby significantly improving the overall efficiency and system power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0009] Figure 2 It is a circuit diagram of a DC transformer module in a hybrid topology architecture and a schematic diagram of the charge transfer relationship;

[0010] Figure 3 It is a schematic diagram of the voltage of key nodes;

[0011] Figure 4 This is a schematic diagram of a digital linear voltage regulator module;

[0012] Figure 5 It is a schematic diagram of the effect of the embodiment;

[0013] Figure 6 This is a schematic diagram of the auxiliary control loop implementation;

[0014] Figure 7 This is the load mutation transient response test result;

[0015] Figure 8 This is the system conversion efficiency test result. DETAILED DESCRIPTION

[0016] like Figure 1 As shown, this embodiment relates to a step-down conversion circuit based on a dual-loop control digital linear voltage regulator module, including: a pair of off-chip ceramic capacitors C H and C L , in the high-side voltage domain V H The hybrid topology DC transformer module and the low-side voltage domain V connected thereto are L The digital linear voltage regulator module, output voltage control loop and auxiliary control loop, among which: the off-chip ceramic capacitor C H and C L The input voltage V in It is divided into high-side and low-side voltage domains. The output currents of the hybrid topology DC transformer module and the digital linear voltage regulator module are added as the total output current. The output voltage of the hybrid topology DC transformer module is fed back to the digital linear voltage regulator module with a high-frequency clock through the output voltage control loop. The input end of the auxiliary control loop is set at a pair of off-chip ceramic capacitors C H and C L The clock signal is output to the hybrid topology DC transformer module to coordinate the regulation of V L The size of the digital linear voltage regulator module enables it to operate in a low voltage difference condition and achieve a high load response speed.

[0017] The dual-loop control means that the output currents of the high-side and low-side voltage domains are added to obtain the total output current, forming a topology architecture with series input and parallel output.

[0018] The overall conversion efficiency of the step-down conversion circuit and the conversion efficiency of the high side and the low side η=η H *V H / V IN +η L *V L / V IN , where: low-side conversion efficiency η L =V O / V L =(V L -VDO ) / V L , η H is the high-side conversion efficiency, V DO is the voltage difference of the digital linear regulator module, V H is the high-side input voltage, V L is the low side input voltage.

[0019] The coordinated regulation refers to: by adjusting the duty cycle of the clock signal, the voltage conversion ratio of the DC transformer module of the hybrid topology architecture is changed accordingly, thereby controlling V H and V L size.

[0020] like Figure 6 As shown, the auxiliary control loop includes: a type II compensator, a sawtooth wave generator, a comparator, an SR latch and a non-overlapping clock generator, wherein: the output voltage V EA and sawtooth wave V RAMP A pulse width modulation signal is generated by a comparator, and then passes through an SR latch and a logic circuit of a non-overlapping clock generator to produce a two-phase non-overlapping clock to be provided to the high-side hybrid topology DC transformer module.

[0021] The type II compensator includes: an operational amplifier, an on-chip capacitor C C1 and C C2 , on-chip resistors R1, R F1 and R F2 , where: On-chip resistance R F1 and R F2 For input voltage V L The voltage is divided and output to the inverting input of the operational amplifier. The reference voltage V REF Input to the positive input terminal of the operational amplifier, the on-chip capacitor C C1 , C C2 The on-chip resistor R1 is set between the inverting input and output of the operational amplifier.

[0022] Under the control of the auxiliary control loop, the digital linear voltage regulator module can maintain a low voltage difference of 0.1V under different input and output voltages and load conditions, thereby improving the overall conversion efficiency.

[0023] like Figure 2As shown, the hybrid topology DC transformer module includes: three capacitors C1-C3, an inductor and 7 power switches S1-S7, wherein: the second capacitor C2 and the inductor are arranged in series between the input end and the output end, the first capacitor C1 is arranged between the input end and the ground potential, the third capacitor C3 is arranged between the output end and the ground potential, and power switches are respectively arranged between the input end, the output end and the ground potential and the three capacitors C1-C3. Through different switch combinations, the connection mode of the inductor, capacitor and switch is alternately changed between the two phases. In phase 1, the third, fourth and sixth power switches S3, S4 and S6 are closed, the first capacitor C1 charges the second capacitor C2, the third capacitor C3 discharges, and the inductor L is magnetized. In phase 2, the first, second, fifth and seventh power switches S1, S2, S5 and S7 are closed, and the first capacitor C1 is connected to V IN and V L The second capacitor C2 charges the third capacitor C3, and the inductor L is demagnetized.

[0024] The first capacitor C1 forms a buffer stage, transferring the charge from C H The inductor is transferred to the ground reference plane and provided to the second capacitor C2 and the third capacitor C3 to form a 2:1 switched capacitor DC transformer. The SW node at the left end of the inductor is connected to the positive plate of the third capacitor C3 in phase 1 and is grounded in phase 2.

[0025] like Figure 3 As shown in FIG. 1 , the voltage C1P of the positive plate of the first capacitor C1 in the hybrid topology DC transformer module is connected to the input voltage V IN , in phase 1 it is equal to V IN -V L , C1 continuously transfers charge from C H The SW node on the left side of the inductor is equal to (V IN -V L ) / 2, grounded in phase 2, and the duty cycle of phase 1 is D. Therefore, according to the volt-second balance principle, the input-output relationship of the high side can be obtained as V OUT =D(V IN -V L ) / 2.

[0026] like Figure 4 As shown, the digital linear voltage regulator module includes: a dynamic comparator, a shift register array and a plurality of power tubes connected in sequence, wherein: the shift register array controls the on or off state of the plurality of power tubes, the dynamic comparator outputs instructions to the shift register array to determine the moving direction of the shift register, and when the output voltage V OUT Lower than the input voltage V REFWhen the shift register moves in the positive direction to turn on more PMOS power tubes, otherwise the shift register moves in the negative direction to turn off more PMOS power tubes. The control clock CLK of the digital linear voltage regulator module LS A high frequency clock.

[0027] The shift register array is preferably a 128-bit bidirectional shift register array, and the corresponding power tubes are 128 groups of PMOS.

[0028] After specific practical experiments, such as Figure 7 As shown in the figure, when the input voltage is 5V, the output voltage is 0.85V, and the load current jumps between 0.1A and 2A, when the load current jumps from 0.1A to 2A, the voltage drops to 36mV and the voltage recovery time is 1.6μs. When the load current jumps from 2A to 0.1A, the voltage rises to 124mV and the recovery time is 7.2μs.

[0029] like Figure 8 As shown in the figure, when the input voltage is in the range of 4V to 5V and the output voltage is in the range of 0.6V to 1V, the circuit achieves a peak conversion efficiency of 92% and can achieve a maximum load current of 5A. When the voltage difference of the low-side digital linear regulator module is reduced from 0.25V to 0.1V by the auxiliary control loop, the peak conversion efficiency of the system is improved by 6.1%. Calculating the volume of the chip, flyback capacitor and inductor, the total volume of this system is 11.56mm 3 , thus achieving 346W / cm 3 system power density.

[0030] like Figure 5 As shown in Figure 1, it is a schematic diagram of the current and voltage response when the load current changes suddenly. When in a stable working state, the output current I OH =I OUT V H / V IN , the low-side output current I OL =I OUT V L / V IN When the load current suddenly increases, the output voltage V OUT When a voltage drop occurs, the digital linear voltage regulator module can quickly detect the change in output voltage and generate a large output current to respond to the change in load current. However, the output current of the high-side DC transformer module can only increase the current at a slower rate due to the current change slope of the inductor. As the output current of the DC transformer module increases, the output current of the digital linear voltage regulator module gradually decreases and eventually returns to a stable working state. The fast response capability of the digital linear voltage regulator module enables the system to have a better load response speed and reduce the voltage drop when the load current changes suddenly.

[0031] Compared with the existing technology, the device adopts a hybrid topology DC transformer module and a digital linear voltage regulator module with series input and parallel output in the circuit architecture, achieving a voltage recovery time of 1.6μs under a 2A load surge. At the same time, due to the combined use of two high power density modules, the hybrid topology DC transformer module and the digital linear voltage regulator module, a maximum output current of 5A and a power of 346W / cm 3 Due to the use of the auxiliary control loop, the low-side digital linear regulator module works in low dropout mode, allowing the overall system to achieve a peak system conversion efficiency of 92%.

[0032] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A step-down conversion circuit based on a dual-loop controlled digital linear voltage regulator module, characterized in that: include: A pair of off-chip ceramic capacitors, a hybrid topology DC transformer module in a high-side voltage domain, and a digital linear voltage regulator module in a low-side voltage domain respectively connected thereto, an output voltage control loop, and an auxiliary control loop, wherein: the off-chip ceramic capacitors and divide the input voltage into a high-side voltage domain and a low-side voltage domain, the output currents of the hybrid topology DC transformer module and the digital linear voltage regulator module are added as the total output current, the output voltage of the hybrid topology DC transformer module is fed back to the digital linear voltage regulator module with a high-frequency clock through the output voltage control loop, the input end of the auxiliary control loop is set between a pair of off-chip ceramic capacitors and, and a clock signal is output to the hybrid topology DC transformer module to match the size of the regulation, so that the digital linear voltage regulator module works in a low voltage difference condition and achieves a high load response speed; The dual-loop control means that the output currents of the high-side and low-side voltage domains are added to obtain the total output current, forming a topology architecture of input series and output parallel connection; The coordinated regulation refers to: adjusting the duty cycle of the clock signal to correspondingly change the voltage conversion ratio of the hybrid topology DC transformer module, thereby controlling the high-side input voltage and the low-side input voltage.

2. The step-down conversion circuit based on the dual-loop controlled digital linear voltage regulator module according to claim 1 is characterized in that: The hybrid topology DC transformer module comprises: three capacitors, an inductor and a power switch, wherein: the second capacitor and the inductor are arranged in series between the input end and the output end, the first capacitor is arranged between the input end and the ground potential, the third capacitor is arranged between the output end and the ground potential, and power switches are arranged between the input end, the output end, the ground potential and the three capacitors respectively, and the connection mode of the inductor, the capacitor and the switch is alternately changed between the two phases through different switch combinations; In phase 1, the third, fourth and sixth power switches are closed, the first capacitor charges the second capacitor, the third capacitor discharges, and the inductor is magnetized; In phase 2, the first, second, fifth and seventh power switches, and are closed, the first capacitor is connected between and charges, the second capacitor charges the third capacitor, and the inductor is demagnetized.

3. The step-down conversion circuit based on the dual-loop controlled digital linear voltage regulator module according to claim 1 is characterized in that: The auxiliary control loop includes: a type II compensator, a sawtooth wave generator, a comparator, an SR latch and a non-overlapping clock generator, wherein: the output voltage V EA and sawtooth wave V RAMP A pulse width modulation signal is generated by a comparator, and then passes through an SR latch and a logic circuit of a non-overlapping clock generator to produce a two-phase non-overlapping clock to be provided to the high-side hybrid topology DC transformer module.

4. The step-down conversion circuit based on the dual-loop controlled digital linear voltage regulator module according to claim 3 is characterized in that: The type II compensator includes: an operational amplifier, an on-chip capacitor C C1 and C C2 , on-chip resistors R1, R F1 and R F2 , where: On-chip resistance R F1 and R F2 For input voltage V L The voltage is divided and output to the inverting input of the operational amplifier. The reference voltage V REF Input to the positive input terminal of the operational amplifier, the on-chip capacitor C C1 , C C2 The on-chip resistor R1 is set between the inverting input and output of the operational amplifier.

5. The step-down conversion circuit based on the dual-loop controlled digital linear voltage regulator module according to claim 1 is characterized in that: The digital linear voltage regulator module comprises: a dynamic comparator, a shift register array and a plurality of power tubes connected in sequence, wherein: the shift register array controls the on or off state of the plurality of power tubes, the dynamic comparator outputs instructions to the shift register array to determine the moving direction of the shift register, and when the output voltage V OUT Lower than the input voltage V REF When the shift register moves in the positive direction to turn on more PMOS power tubes, otherwise the shift register moves in the negative direction to turn off more PMOS power tubes. The control clock CLK of the digital linear voltage regulator module LS A high frequency clock.

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