Power Gating with Current Limiter for Standby Data Retention
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Solution Overview
Problem
Conventional power gating devices in mobile electric devices face challenges in reducing power consumption during stand-by mode while retaining data, as they often require additional devices to prevent data loss when power is blocked to function blocks.
Innovation Solution
A power gating device with a control unit that generates interrupt signals for mode changes, a memory unit for data storage and restoration, and a power source unit that manages power states to reduce consumption and retain data without additional devices like MTCMOS or retention flip-flops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power is blocked to function blocks in stand-by mode to reduce power consumption, then power consumption is reduced, but data of the function blocks is lost
Solution Approach 1:
The system segments power supply into two distinct paths: a main power path through the regulator for normal operation, and a standby power path through the current limiter for data retention. This segmentation allows different power management strategies for different operational states without requiring additional retention devices.
Solution Approach 2:
The system changes the power supply parameter from full power (through regulator) to reduced power (through current limiter) when transitioning to standby mode. The current limiter provides just enough power to maintain data in memory blocks while consuming significantly less power than the regulator would provide, thus resolving the contradiction between power reduction and data retention.
2Use of energy by moving object
If conventional power gating is used to reduce power consumption, then power consumption is reduced, but additional devices are required to prevent data loss
Solution Approach 1:
The current limiter serves multiple functions: it acts as a power reduction element during standby mode, a data retention power source, and implicitly replaces the need for separate retention flip-flops or MTCMOS circuits. This multi-functionality reduces overall device complexity while achieving both power reduction and data retention.
Solution Approach 2:
The invention extracts the data retention function from the main power gating mechanism. Instead of using complex retention circuits, the system extracts and utilizes the natural data retention capability of memory blocks by providing them with minimal power through the current limiter during standby mode, thereby eliminating the need for additional retention devices.
3Use of energy by moving object
If power is completely cut off to function blocks, then power consumption is minimized, but power/ground bouncing occurs during mode changes
Solution Approach 1:
The system provides beforehand cushioning by maintaining a minimal power path through the current limiter even during standby mode. This residual power path acts as a cushion that prevents abrupt power transitions and associated bouncing effects when transitioning between normal and standby modes, while still achieving significant power reduction compared to full operation.
Data Source
AI summary
A power gating device may include a control unit that generates a first interrupt signal based on a mode change signal when a mode of a system is changed from a normal operation mode to a stand-by mode, and generates a second interrupt signal based on the mode change signal when the mode is changed from the stand-by mode to the normal operation mode, a memory unit that stores data of a function block based on the first interrupt signal, and restores the stored data to the function block based on the second interrupt signal, and a power source unit that provides a normal operation power to the function block and the memory unit based on a power down signal in the normal operation mode, and provides a stand-by power to the memory unit based on the power down signal in the stand-by mode.