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CN-122001213-A - Single inductor multiple output DC-DC converter and method of operation

CN122001213ACN 122001213 ACN122001213 ACN 122001213ACN-122001213-A

Abstract

A single inductor multiple output DC-DC converter and method of operation. A SIMO-DC converter with a modified buck topology, wherein multiple outputs are supplied from a single inductor. When the inductor discharges, the supply order of the outputs is reversed so that the inductor current at the end of the supply of the outputs can be reset to the same value it had at the beginning of the supply of the same outputs in the same cycle.

Inventors

  • M. Sulaki

Assignees

  • 商升特公司

Dates

Publication Date
20260508
Application Date
20250926
Priority Date
20241107

Claims (17)

  1. 1. A single inductor multiple output circuit with a modified buck topology in which multiple outputs are selectively and cyclically connectable to a single inductor, characterized in that when the inductors discharge, the supply order of the outputs is reversed so that the inductor current at the end of supply of an output can be reset to the same value it had at the beginning of supply of the same output in the same cycle.
  2. 2. The circuit of claim 1, wherein the first terminal of the inductor is connected to a left side switching circuit operable to inject current into the inductor from the power supply terminal or from the ground terminal, the right side switching circuit operable to connect the second terminal of the inductor to one of the plurality of output terminals, the circuit configured to generate a timing signal for connecting the first terminal of the inductor to a higher potential or a lower potential based on an error signal derived from a comparison of one of the output voltages to a reference value.
  3. 3. The circuit of claim 2, wherein the control circuit is configured to cyclically operate the left and right switching circuits such that the potential of the output terminal is stabilized to a predetermined voltage value, the operating cycle of the control circuit including a charging portion in which the left switching circuit is operated such that the current flowing in the inductor rises and a discharging portion in which the left switching circuit is operated such that the current flowing in the inductor falls, wherein the control circuit is configured to select one of the output terminals with the right switching circuit being operated at a time that follows a supply order during the charging portion and that follows a reverse order during the discharging portion, and to time the left and right switching circuits such that, at the end of each supply interval of the output terminal during the discharging portion, the current flowing in the inductor returns to a value that it has at the beginning of the supply interval of the same output terminal during the charging portion.
  4. 4. A circuit according to claim 3, the left side switching circuit comprising a half bridge having a high side switch and a low side switch, the half bridge being operable to allow current to flow between the first terminal of the inductor and the power supply, between the first terminal of the inductor and ground, respectively.
  5. 5. The circuit of claim 1, the right side switching circuit comprising a plurality of output switches, each output switch operable to connect the second terminal of the inductor to one of the output terminals.
  6. 6. The circuit of claim 1, the number of output terminals being two, three or more.
  7. 7. The circuit of claim 1, the loop of the control circuit having a fixed frequency.
  8. 8. The circuit of claim 1, comprising a zero current detector, the control circuit configured to activate a freewheel mode in which the right and left sides are set in a high impedance mode and the bypass switch is closed to short the inductor when the zero current detector signals that the inductor current reaches zero.
  9. 9. A circuit according to claim 1, comprising a feedback loop for each voltage output, the feedback loop comprising a modulator providing a timing signal to the left side switching circuit and/or the right side switching circuit, the timing signal being driven by an error signal derived from a comparison of the output voltage with a reference value.
  10. 10. The circuit of claim 9, the feedback loop comprising a PI compensator or a PID compensator.
  11. 11. A method of operating a Single Inductor Multiple Output (SIMO) DC-DC converter, comprising an operating cycle comprising a charging portion in which a first terminal of an inductor is connected to a potential higher than an output potential such that a current flowing in the inductor rises, and a discharging portion in which a first terminal of the inductor is connected to a lower potential such that a current flowing in the inductor falls, while a second terminal of the inductor is switched to one of the output terminals during the charging portion following a supply order and at a time following a reverse order during the discharging portion such that at the end of each supply interval of the output terminals during the discharging portion, a current flowing in the inductor returns to a value it had at the beginning of a supply interval of the same output terminal during the charging portion.
  12. 12. The method of claim 11, wherein at the end of supplying the output, the current flowing in the inductor in each cycle is reset to the same value it had at the beginning of supplying the same output in the same cycle.
  13. 13. The method of claim 12, the number of output terminals being two, three or more.
  14. 14. The method of claim 11, the cycle of the control circuit having a fixed frequency.
  15. 15. A method according to claim 11, comprising activating a freewheel mode when the inductor current reaches zero, wherein the inductor is not connected to the output terminal and is shorted by the bypass switch.
  16. 16. A method according to claim 11, comprising storing the value of the inductor current in the charging section at the start of supply of the output and terminating the supply of the same output in the discharging section when the inductor current reaches the stored value, or estimating the time at which the inductor current supplying the output in the discharging section will reach the same value it had at the start of supplying the same output in the charging section and terminating the supply of the output at the estimated time.
  17. 17. The method of claim 11, comprising generating a timing signal for connecting the first terminal of the inductor to a higher or lower potential based on an error signal derived from a comparison of one of the output voltages to a reference value.

Description

Single inductor multiple output DC-DC converter and method of operation Technical Field In an embodiment, the present invention relates to a power supply and management circuit that provides multiple power rails, and an algorithm that generates multiple independent power levels in a circuit with a single storage inductor. As complexity and integration increases, power management circuits are increasingly required to provide several different power rails for different points of load and different applications, each power rail having a particular set of requirements. A single integrated circuit or chip may be required to power both the external companion chip as well as internal functions (such as low power radios). These multi-function systems require a stable power supply for both analog and digital sections that respect the stringent EMI limitations of analog/radio circuits and provide high performance load regulation for digital circuits. Still further, in most applications, particularly in IoT hardware, energy efficiency, voltage rail adaptation, low cost BOM is expected. Meeting all of these opposite requirements is highly challenging. In the market today, PMIC (power management integrated circuit) is highly popular for meeting these requirements. These PMICs often include multiple inductive DC/DC converters, LDOs, and other auxiliary functions. These circuits offer significant advantages over older single point load (PoL) solutions and discrete converter circuits. SIMO (single inductor, multiple output) converters promise even better BOM savings by requiring only a single inductor to provide multiple voltage rails. Document EP 4387073 A1 discloses a single inductor, multiple output DC-DC converter. US 20240333155 A1 and US 9293319 B2 disclose SIMO DC-DC converters with a feedback circuit that orchestrates the commutation (orchestrate the commutation) between the outputs. The technical article "SINGLE DISCHARGE Control for Single-Inductor Multiple-Output DC-DC Buck Converters" by Tae Young Goh and 10 Wai Tung Ng, disclosed in "IEEE Transactions on Power Electronics" (Vol.33, 3, 2018, pages 2307-2316,1), discloses a SIMO converter with a zero current detector. Disclosure of Invention It is an object of the present invention to provide a multiple output voltage converter that overcomes at least some of the disadvantages and limitations of the prior art. Embodiments of the present invention provide excellent performance in terms of both efficiency and stability while remaining simple enough for easy integration into a high volume production stream. According to the present invention, these objects are achieved by the objects of the appended claims, and in particular by a single-inductor multiple-output (SIMO) circuit having a modified buck topology in which a plurality of outputs are selectively and cyclically connectable to a single inductor, characterized in that when the inductor discharges, the supply (serving) order of the outputs is reversed, so that the inductor current at the end of the supply of the outputs can be reset to the same value it had at the beginning of the supply of the same outputs in the same cycle. The dependent claims introduce important aspects of the invention, namely that, although they are advantageous, they are not essential. For example, a modified buck converter configuration in which a first inductor terminal is connected to a left side switching circuit with a half bridge between the power supply terminal and ground, and a second terminal of the inductor is linked to an array of output switches, one for each output. In an embodiment, the controller circuit determines the timing of the various switches such that in a first charging portion of each cycle, the inductor current rises while the output terminals are supplied one by one, and in a second discharging portion of each cycle, the output terminals are supplied in reverse order while the inductor current falls. The timing of the switch is such that at the end of each supply interval of the terminals during the discharge portion, the current flowing in the inductor returns to the value it had at the beginning of the supply interval of the same output terminal during the charge portion. Many valuable uses require two independent output terminals, but the number of outputs is not limited in the present invention. They may be two, three or more. As regards the switches, they can be implemented with MOS transistors. The converter may operate at a fixed frequency cycle, which is advantageous for EMI, or in a variable frequency mode if desired. In the former case, it may be advantageous to introduce a freewheel phase in each cycle, so that the converter can operate in discontinuous current mode at low loads without changing frequency. The freewheel mode may be triggered by a zero-current detector and involves isolating the inductor from the switching circuit on the right side or on both sides (the switch is placed in a high im