Safety Timer Circuit Adjusting Timeout by Charge Current
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Solution Overview
Problem
Existing battery charging systems face challenges in controlling the charging process effectively, particularly in preventing overcharging, as they often rely on fixed time-out mechanisms that do not account for varying charge currents, leading to potential damage to rechargeable batteries.
Innovation Solution
A circuit and method that adjust the safety time-out based on the charge current by using a signal derived from the charge current to control an oscillator, which regulates a voltage-current control loop, incorporating a digital current-set circuit and Digital-to-Analog Converter (DAC) to determine and limit the charge current, and employing a safety timer circuit with a time-out counter that adjusts the timeout period inversely proportional to the charging current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed time-out mechanism is used for battery charging safety, then the charging control is simple, but the battery may be overcharged or undercharged due to varying charge currents
Solution Approach 1:
The patent applies the dynamics principle by making the time-out value dynamic rather than fixed. The time-out counter is adjusted based on the charge current magnitude: higher currents result in shorter time-out periods, while lower currents result in longer time-out periods. This dynamic adjustment ensures accurate charging termination across different charging conditions without requiring complex external control circuits.
Solution Approach 2:
The patent implements feedback by using the charge current signal to control the time-out counter adjustment. The system continuously monitors the charge current and uses this information to modify the time-out period, creating a closed-loop control system that adapts to varying charging conditions and prevents both overcharging and undercharging.
2Measurement precision
If a dynamic time-out adjustment based on charge current is implemented, then the charging accuracy is improved, but the circuit complexity increases
Solution Approach 1:
The patent applies universality by designing the time-out counter to serve multiple functions: it acts as both a safety timer and a charge level detector. The same counter that provides safety time-out also accurately detects charge completion by adjusting its termination threshold based on charge current, eliminating the need for separate detection circuits and reducing overall system complexity.
Solution Approach 2:
The patent implements parameter changes by modifying the time-out counter's operational parameters (counting threshold and time constant) based on the charge current magnitude. This allows the system to achieve high measurement precision for charge level detection while using a single versatile component rather than multiple specialized circuits.
3Adaptability or versatility
If different charging modes (fast charge, quick charge, standard charge, trickle charge) are supported, then the battery charging flexibility is improved, but the charging control complexity increases
Solution Approach 1:
The patent applies dynamics by enabling the charging control system to dynamically adapt to different charging modes through automatic current-based time-out adjustment. Whether operating in fast charge, quick charge, standard charge, or trickle charge mode, the system automatically adjusts the time-out period according to the actual charge current, providing charging flexibility without requiring separate control logic for each mode.
Data Source
AI summary
A method and circuit for adjusting a safety time-out in charging devices based on a charge current. According to one embodiment, a signal that is based on the charge current is employed to control an output of an oscillator, which controls an operation of a safety timer circuit. The safety timer circuit activates or deactivates a voltage-current (V-I) control loop of the charging device providing the safety time-out based on the charge current. In another embodiment, where a digital current-set circuit may be employed to determine a value of the charge current, a Digital-to-Analog Converter (DAC) may provide the charge current limit to the V-I control loop, and another output of the digital current-set circuit may control the safety timer. In a further embodiment, a signal based on the charge current may be digitized and employed to control the safety timer comprising a time-out counter.