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CN-112532036-B - Soft start method for single-inductor multi-output power supply

CN112532036BCN 112532036 BCN112532036 BCN 112532036BCN-112532036-B

Abstract

A method for a soft start Single Inductor Multiple Output (SIMO) power supply is provided. The method includes selecting operation in a Pulse Width Modulation (PWM) mode. A first Pulse Frequency Modulation (PFM) mode is enabled to supply a first voltage to a first load, and the power supply begins to ramp up an output voltage. After the output voltage has reached a desired value in the PFM mode, the PFM mode is disabled. Subsequently, operation is enabled in the PWM mode. The SIMO power supply then supplies current to one or more loads in the PWM mode.

Inventors

  • Christian Vincent sores
  • Nicholas Patrick vantalon

Assignees

  • 恩智浦有限公司
  • 恩智浦有限公司

Dates

Publication Date
20260421
Application Date
20200828
Priority Date
20190919

Claims (6)

  1. 1. A method for soft start single inductor multiple output SIMO power supply, the method comprising: Selecting a Pulse Width Modulation (PWM) mode; Enabling a first pulse frequency modulated PFM mode in the SIMO power supply; Supplying a first voltage to a first load while in the first PFM mode; disabling the first PFM mode; Enabling the PWM mode in the SIMO power supply, and Operating the SIMO power supply in the PWM mode, Wherein operating the SIMO power supply in the PWM mode further comprises: Selecting a second PFM mode after disabling the first PFM mode and before operating the SIMO power supply in the PWM mode, and Supplying the first voltage to the first load and supplying a second voltage to a second load while in the second PFM mode, And wherein supplying the first voltage to the first load and supplying a second voltage to a second load in the second PFM mode further comprises: charging the single inductor in the second PFM mode; Discharging the single inductor through the first load in the second PFM mode; recharging the single inductor in the second PFM mode, and The single inductor is discharged in the second PFM mode by the second load.
  2. 2. The method of claim 1, further comprising controlling the SIMO power supply using a finite state machine.
  3. 3. A method according to any of the preceding claims, wherein the second voltage is higher than the first voltage.
  4. 4. The method of claim 3, wherein the second voltage is higher than a supply voltage provided to the SIMO power supply and the first voltage is lower than the supply voltage.
  5. 5. The method of claim 4, further comprising providing the supply voltage from a battery.
  6. 6. The method of any of the preceding claims, wherein operating the SIMO power supply in the PWM mode further comprises providing a clock in PWM mode.

Description

Soft start method for single-inductor multi-output power supply Technical Field The present disclosure relates generally to electronic circuits, and more particularly, to a soft start method for a Single Inductor Multiple Output (SIMO) power supply. Background Integrated circuits require at least one DC voltage source and typically more than one DC voltage source. Single Inductor Multiple Output (SIMO) is a switched mode power supply that uses only one inductor and a feedback control circuit to generate two or more regulated DC output voltages. Various modulation techniques are used in the design of the switched mode power supply. One approach uses Pulse Width Modulation (PWM). The PWM scheme uses a clock with a fixed frequency that is applied to the switches of a switch mode power supply to power a load. In general, PWM converters are used for applications requiring high efficiency under heavy load. During the SIMO startup sequence, the inrush current may be high enough to cause an over-current or over-voltage condition and damage components powered by the SIMO power supply. To prevent high inrush currents at the start-up of the SIMO power supply, various soft start circuits are used that require additional components to limit the inrush current, prevent over-currents in the inductor and over-voltages on the output. The additional components add complexity, increase cost, and increase area to the integrated circuit implementation of the PWM switch-mode power supply. Thus, there is a need for a soft start technique for PWM switched mode power supplies that does not require additional components. Disclosure of Invention According to a first aspect of the present invention there is provided a method for soft start Single Inductor Multiple Output (SIMO) power supply, the method comprising: Selecting a Pulse Width Modulation (PWM) mode; enabling a first Pulse Frequency Modulation (PFM) mode in the SIMO power supply; Supplying a first voltage to a first load while in the first PFM mode; disabling the first PFM mode; Enabling the PWM mode in the SIMO power supply, and The SIMO power supply is operated in the PWM mode. In one or more embodiments, the method further includes controlling the SIMO power supply using a finite state machine. In one or more embodiments, operating the SIMO power supply in the PWM mode further comprises: Selecting a second PFM mode after disabling the first PFM mode and before operating the SIMO power supply in the PWM mode, and The first voltage is supplied to the first load and a second voltage is supplied to a second load while in the second PFM mode. In one or more embodiments, the method further comprises simultaneously supplying the first voltage to the first load and the second voltage to the second load in the first PFM mode further comprises charging a single inductor through the first load and the second load. In one or more embodiments, supplying the first voltage to the first load and supplying a second voltage to a second load in the second PFM mode further comprises: charging the single inductor in the second PFM mode; Discharging the single inductor through the first load in the second PFM mode; recharging the single inductor in the second PFM mode, and The single inductor is discharged in the second PFM mode by the second load. In one or more embodiments, the second voltage is higher than the first voltage. In one or more embodiments, the second voltage is higher than a supply voltage provided to the SIMO power supply and the first voltage is lower than the supply voltage. In one or more embodiments, the method further comprises providing the supply voltage from a battery. In one or more embodiments, operating the SIMO power supply in the PWM mode further includes providing a clock in PWM mode. According to a second aspect of the present invention there is provided a method for soft start Single Inductor Multiple Output (SIMO) power supply, the method comprising: Selecting a Pulse Width Modulation (PWM) mode; charging a single inductor in a first Pulse Frequency Modulation (PFM) mode; discharging the single inductor through a first load in the first PFM mode; Recharging the single inductor in the first PFM mode; Discharging the single inductor in the first PFM mode by a second load; disabling the first PFM mode; enabling the PWM mode after disabling the first PFM mode, and The SIMO power supply is operated in the PWM mode. In one or more embodiments, the method further includes controlling the SIMO power supply using a finite state machine. In one or more embodiments, operating the SIMO power supply in the PWM mode further comprises: Charging the single inductor to a first voltage in the PWM mode, and The single inductor is sequentially discharged from the first voltage to a second voltage by the first load and then by the second load. In one or more embodiments, the method further comprises enabling a second PFM mode prior to selecting the first PFM mode during a soft sta