Charge Control Circuit Diode OR Feedback Loop Transition
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Solution Overview
Problem
Existing charge control devices face issues with sudden changes in system current, leading to overcurrent flow in secondary batteries due to restrictions in adaptor and charge currents, requiring a circuit to prevent overshoot during transitions between constant current control loops.
Innovation Solution
A charge control device with a charge control circuit incorporating first and second error amplifiers, a control signal generator, and a PWM comparator to manage feedback voltages and currents, ensuring stable transitions and preventing overcurrent by generating appropriate control signals for the output stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant current control restricts the adaptor current to a predetermined value, then over supply of current from the adaptor is prevented, but the charge current is restricted to a value smaller than the value set by the feedback loop
Solution Approach 1:
The patent introduces a diode OR circuit as an intermediary component that selectively passes the higher voltage signal between the first feedback loop (adaptor current control) and the second feedback loop (charge current control). This mediator allows the system to automatically switch between control modes based on which loop requires greater current restriction, resolving the contradiction by enabling both protection functions to operate without mutual interference.
2Productivity
If the constant current control on the adaptor current is finished and the charge current is increased, then the charge current can reach the set value, but there is a risk of current larger than predetermined value flowing due to restart from over range state
Solution Approach 1:
The patent applies preliminary action by maintaining the output of the second error amplifier in a controlled state through the diode OR circuit even when the first feedback loop is inactive. The diode ensures that the second feedback loop is pre-positioned to accept control signals properly, preventing the amplifier from operating in an over-range state that would cause current overshoot when the loop is reactivated.
3Adaptability or versatility
If multiple feedback loops are connected in parallel for constant current and voltage control, then comprehensive control functions are achieved, but the system becomes complex and requires additional circuits like soft start
Solution Approach 1:
The patent merges the control functions of multiple feedback loops by connecting them through a diode OR circuit configuration. This combining approach allows the first feedback loop (adaptor current control) and the second feedback loop (charge current control) to share a common control path, eliminating the need for separate control circuits and reducing overall system complexity while maintaining comprehensive control capabilities.
Data Source
AI summary
A charge control device includes a charge control circuit to control a charge of a secondary battery by controlling an output stage connected between a power supply and the secondary battery. The charge control circuit includes a first error amplifier to generate a first error voltage in response to a difference between a predetermined first reference voltage and a first feedback voltage. The value of the first feedback voltage is determined in accordance with a primary current supplied from the power supply to the output stage. The charge control circuit also includes a second error amplifier to generate a second error voltage in response to a difference between either one of a predetermined second reference voltage and the first error voltage, and a second feedback voltage. The value of the second feedback voltage is determined in accordance with a charge current supplied from the output stage to the secondary battery. The charge control circuit also includes a control signal generator to generate the control signal of the output stage in response to the second error voltage.