# US 9,882,475 B2 · PWM calculation after light load to high load transition

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- Number: US 9,882,475 B2
- Document ID: US9882475B2
- Status: Granted
- Kind: B2
- Application number: 14/890,835
- Filed: 2014-05-23
- Published: 2016-04-28
- Granted: 2018-01-30
- Earliest claimed: 2013-05-24
- Assignees: IDT Europe GmbH
- Applicants: IDT Europe GmbH
- Inventors: Richard Maria Schmitz; Eric Marschalkowski; Chris Young
- Web page: https://patentgrep.com/patent/US9882475B2

## CPC

- H02M 3/157: with digital control
- H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators
- H02M 3/158: including plural semiconductor devices as final control devices for a single load
- H02M 1/0032: {Control circuits allowing low power mode operation, e.g. in standby mode}
- H02M 1/32: Means for protecting converters other than automatic disconnection
- H02M 3/1588: {comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence)}
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A switchable power converter includes a switchable power stage comprising an inductor and a capacitor for generating an output voltage according to a switching signal and an input voltage via a switching element comprising a high-side switch and a low-side switch driven by a driver according to the switching signal generated either in a digital control path or a constant-on-time control path. A multi-mode controller is configured to toggle between a light load mode in which the constant-on-time control path is activated and a high load mode in which the digital control path is activated. The multi-mode controller is further configured to generate a control signal for turning on the high-side switch for an additional time when transitioning from the light load mode to the high load mode.

## Claims

### Claim 1

A switchable power converter, comprising:
a switchable power stage comprising an inductor and a capacitor for generating an output voltage according to a switching signal and an input voltage by a dual switching element comprising a high-side switch and a low-side switch, wherein the switching signal is generated either in a digital control path or a constant on-time control path;
a multi-mode controller configured to toggle between a light load mode in which the constant-on-time control path is activated and a high load mode in which the digital control path is activated,
wherein the multi-mode controller is further configured to generate the switching signal for turning on the high-side switch for an additional time triggered by and added to an end of a transition interval from the light load mode to the high load mode, wherein the multi-mode controller is further configured to generate the switching signal for turning on the high-side switch by extending duration of an on-time of a control signal generated in the constant on-time control path, and wherein the multi-mode controller is configures to extend the duration of the on-time of the control signal generated in the constant on-time control path when an equality of a load current and an inductor current is determined, wherein the multi-mode controller is configured to extend the duration of the on-time of the control signal generated in the constant on-time control path by half of a normal on-time period of the control signal in high load mode, and wherein the multi-mode controller is configured to extend the duration of the on-time of the control signal generated in the constant on-time control path by the additional time Ton-additional=Vout/Vin*TPWM*0.5, wherein Vout is the output voltage of the switchable power stage, Vin is the input voltage, and TPWM is a duty cycle of a pulse width modulation signal controlling the dual switching element.

### Claim 2 (depends on 1)

The switchable power converter according to claim 1, wherein the digital control path comprises an error amplifier to amplify a difference between the output voltage and a reference voltage for generating an error signal; an analog to digital converter to convert the error signal to a digitized error signal; a PID compensator to process the digitized error signal for calculating a pulse width modulation duty cycle provided to a digital pulse width modulator to generate a digital pulse width modulation switching signal.

### Claim 3 (depends on 2)

The switchable power converter according to claim 2, wherein the constant-on-time control path comprises a comparator configured to compare the output voltage generated in the switchable power stage and the reference voltage; a constant-on-time circuit connected to the comparator and a minimum-off-time circuit connected between a constant-on-time circuit and the multimode controller to guarantee that a sum of the constant on-time and a minimum off-time is greater than a normal period of the digital pulse width modulation signal.

### Claim 4 (depends on 3)

The switchable power converter according to claim 3, wherein the multimode controller is configured to activate the digital control path when the sum of the constant on-time and the minimum off-time is not greater than the normal period of the digital pulse width modulation signal.

### Claim 5 (depends on 1)

The switchable power converter according to claim 1, further comprising a driver with zero current detection to drive the dual switching element according to the switching signal; and a multiplexer controlled by the multimode controller to forward the control signal either generated in the constant on-time control path or the digital control path to the driver.

### Claim 6 (depends on 1)

The switchable power converter according to claim 1, wherein the switchable power stage further comprises a third switching element to short-circuit the inductor for draining an excessive inductor current.

### Claim 7

A method for controlling a multi-mode switchable power converter comprising a switchable power stage with a dual switching element comprising a high-side switch and a low-side switch, an inductor and a capacitor, the method comprising:
generating a switching-a signal for turning on the high-side switch for an additional time triggered by and added to an end of a transition interval between a light load mode in which a constant on-time control path is activated and a high load mode in which a digital control path is activated, wherein generating the switching signal for turning on the high side switch comprises extending duration of an on-time of a switching signal generated in the constant on-time control path; and extending the duration of the on-time of the switching signal generated in the constant on-time control path when an equality of a load current and an inductor current is determined, wherein generating the switching signal for turning on the high side switch comprises extending duration of the on-time of the switching signal generated in the constant on-time control path by half of a normal on-time period of a control signal in high load mode, and wherein generating the switching signal for turning on the high side switch comprises extending the duration of the on-time of the switching signal generated in the constant on-time control path by the additional time Ton-additional=Vout/Vin*TPWM*0.5, wherein Vout is an output voltage of the switchable power stage, Vin an input voltage and TPWM is a duty cycle of a pulse width modulation signal controlling the dual switching element.