Digitally Controlled Current-Mode Power Supply Architecture

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Solution Overview

Problem

Existing switched power supplies face challenges with analog components, including variability with manufacturing, temperature, and noise sensitivity, as well as limitations in digital control systems like DPWM, which require high-frequency clocks and increase power consumption and die area, while also introducing EMI and area inefficiencies.

Innovation Solution

A digitally controlled current-mode power supply architecture that uses a switching element, digital control circuit with a difference circuit, converter, and comparator to produce an error voltage and compare peak current threshold values, eliminating the need for high-speed clocks and analog components, and allowing for programmable duty cycles and overcurrent protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If digital pulse width modulator (DPWM) architecture is used to increase switching frequency, then power stage size is reduced, but power consumption increases and die area increases

Engineering Contradiction:

Improvepower stage sizeVSAvoidpower consumption

Core Design Contradiction:

Volume of moving objectVSUse of energy by stationary object

Solution Approach 1:

The patent replaces the mechanical/clock-based DPWM system with a current-mode digital control system. Instead of using high-frequency clocks and counters to generate PWM signals, the system uses digital control of current modes directly, eliminating the need for high-speed clock circuits and reducing power consumption while maintaining small power stage size

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from duty cycle (in DPWM) to current mode parameters. By controlling the power supply through current modes rather than pulse width modulation, the system achieves high switching frequency benefits without requiring high-frequency clock signals, thus reducing power consumption

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If digital pulse width modulator (DPWM) architecture is used to increase switching frequency, then power stage size is reduced, but die area increases

Engineering Contradiction:

Improvepower stage sizeVSAvoiddie area

Core Design Contradiction:

Volume of moving objectVSArea of stationary object

Solution Approach 1:

The patent replaces the clock-based DPWM architecture with a current-mode digital control system, eliminating high-speed clock circuits, counters, and comparators that occupy significant die area. The current-mode approach uses simpler digital logic that requires less silicon real estate while enabling high switching frequency operation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The current-mode digital control circuit performs multiple functions (control, timing, and regulation) that in DPWM architecture required separate dedicated circuits. This multi-functionality reduces the overall die area by consolidating control functions into a more integrated current-mode system

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If analog control circuits are used, then continuous resolution is achieved, but noise sensitivity increases and manufacturing variability affects performance

Engineering Contradiction:

Improvecontrol resolutionVSAvoidnoise sensitivity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent substitutes analog control circuits with digital control circuits. Instead of using analog voltage or current signals that are susceptible to noise and manufacturing variations, the system uses digital signals and digital control logic, which are inherently more immune to noise and less sensitive to process variations while maintaining continuous resolution through digital precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses digital representation of control parameters instead of direct analog signals. By copying the control information into digital form, the system preserves the continuous resolution information while protecting it from noise and manufacturing variability that affect analog circuits

Inventive Principle:

Principle #26Copying

4Measurement precision

If high-frequency clocks are used in DPWM to achieve sufficient resolution, then resolution is improved, but power consumption increases

Engineering Contradiction:

ImprovePWM resolutionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

The patent changes the resolution achievement mechanism from time-based (high-frequency clock cycles) to current-mode digital precision. By using digital current mode control with precise digital-to-current conversion, the system achieves high resolution without requiring high-frequency clock signals, thus eliminating the associated power consumption

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7907428B2Digitally controlled current-mode switched power supply

Publication Date: 2011.03.15 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

Disclosed is a current mode switched power supply. The current mode switched power supply includes a switching element and a power stage coupled to the switching element and configured to provide, in response to the switching of the switching element, an output voltage and a feedback voltage related to the output voltage. The current mode switched power supply also includes a digital control circuit connected to the switching element to digitally control the switching of the switching element.