RTC CMOS Power Management via Protection IC
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Solution Overview
Problem
In portable information handling systems, the direct power draw from the battery to the real time clock (RTC)/CMOS can lead to unmanaged power draws, resulting in undervoltage and overtemperature conditions due to the battery being discharged too deeply.
Innovation Solution
A power module supplies power to the RTC circuit through a switch controlled by a protection integrated circuit, which monitors battery conditions and disconnects power if predetermined limits are exceeded, ensuring voltage, current, and temperature constraints are maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RTC/CMOS draws power directly from the battery cell, then the RTC can operate independently during system power down, but the battery can be discharged too deeply causing undervoltage and overtemperature conditions
Solution Approach 1:
A protection integrated circuit is introduced as an intermediary between the battery and RTC/CMOS power draw. This protection circuit monitors battery conditions and controls a switch to disconnect power when undervoltage or overtemperature conditions are detected, preventing direct unmanaged power draws from damaging the battery while still allowing RTC operation during system power down.
2Adaptability or versatility
If the RTC/CMOS draws power from the integrated battery, then the system can maintain time tracking during portable operation, but the power management becomes complex requiring additional monitoring circuits
Solution Approach 1:
The protection integrated circuit serves multiple functions: it monitors battery voltage, monitors battery temperature, controls the power switch to the RTC/CMOS, and provides undervoltage protection. By consolidating these multiple protection and monitoring functions into a single circuit, the patent achieves portable operation capability without proportionally increasing system complexity.
Data Source
AI summary
An information handling system real time clock (RTC)/CMOS circuit is powered from a battery that powers the information handling system. The battery power is supplied through a power management circuit that manages power constraints to the real time clock and that protects the battery from exceeding current and voltage thresholds. A protection integrated circuit selectively cuts off power supply from a power module to the RTC/CMOS circuit if predetermined conditions are detected. The protection circuit may also cutoff all power from battery with a permanent failure option or may itself directly supply power to the real time clock/CMOS circuit.