Battery Protection IC Mode Control Circuit
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Solution Overview
Problem
Conventional lithium ion battery protection ICs require additional test mode terminals to reduce delay times during testing, increasing costs and preventing effective testing of overcharge voltage detection functions.
Innovation Solution
A charge and discharge control circuit with a mode control part that manages normal, time-shortening, and protection modes, allowing transitions based on voltage and current detection, enabling testing without additional terminals by shortening delay times for detection functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a test mode terminal is added to reduce delay time during testing, then testing efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The power terminal is designed to serve multiple functions: it acts as both the normal power supply terminal and the test mode input terminal. By applying a voltage higher than the overcharge detection threshold to the power terminal, the system automatically enters test mode, eliminating the need for a separate test mode terminal while maintaining all detection functions.
Solution Approach 2:
The system changes its operational parameters based on the voltage level applied to the power terminal. When the voltage exceeds a predetermined threshold (higher than the overcharge detection threshold), the delay times in the detection circuits are automatically shortened, switching from normal operation mode to test mode without requiring additional hardware controls.
2Loss of time
If delay time is reduced for testing, then testing time is shortened, but detection accuracy may be compromised
Solution Approach 1:
The delay time parameter is made dynamic rather than fixed. The delay time adjustment circuit automatically adjusts the delay time based on the operating mode: using longer delay times during normal operation to ensure detection accuracy, and shorter delay times during test mode to reduce testing time. This dynamic adjustment resolves the contradiction between speed and accuracy.
Solution Approach 2:
The system performs preliminary setup by applying a specific voltage level to the power terminal before actual testing begins. This preliminary voltage application configures the detection circuits with appropriate delay times for testing, ensuring that when tests are conducted, the circuits are already optimized for fast yet accurate detection.
3Speed
If voltage threshold for time-shortening mode is set higher, then delay time is reduced, but overcharge detection function cannot be tested
Solution Approach 1:
The voltage threshold is segmented into two distinct levels: the overcharge detection threshold for normal operation and a higher test mode activation threshold. This segmentation allows the system to differentiate between normal overcharge conditions (which trigger at the lower threshold) and test mode activation (which requires the higher threshold), enabling both functions to coexist without interference.
Data Source
AI summary
In a charge and discharge control circuit, a mode control part manages a normal mode in which voltages at a power terminal and an overcurrent detection terminal are monitored, a time-shortening mode in which predetermined delay times for detecting an overcharge, an overdischarge, and an overcurrent are shortened, and a protection mode in which a signal to stop a charge current or a discharge current is output when an abnormality is detected in the normal mode. A transition is made from the normal mode to the time-shortening mode when the voltage at the power terminal exceeds a predetermined value, and a transition is made from the time-shortening mode to the protection mode when one of the overcharge, overdischarge, and overcurrent is detected.