Dual-Range Charging Circuit With Safe Current Mode Switching
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Solution Overview
Problem
Existing circuit devices face challenges in handling large charging currents to low currents efficiently, particularly in constant-current battery charging, where increasing the maximum charging current reduces current setting resolution or requires an increased circuit scale, and there are issues with unintended large currents during mode switching due to signal delay differences.
Innovation Solution
A circuit device with a current source circuit, a first charging circuit, a second charging circuit, and a control circuit that switches between two current modes based on a current setting value, using a backflow prevention circuit to manage charging currents and reduce unintended large currents by setting the output current of the current source circuit to zero or reducing it during switching periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum charging current is increased, then the charging speed is improved, but the current setting resolution decreases
Solution Approach 1:
The patent divides the charging circuit into multiple charging circuits with different current amplification factors. Each charging circuit handles a specific current range, allowing the system to achieve both high maximum current and fine resolution by selecting the appropriate charging circuit based on the required current level.
Solution Approach 2:
The patent introduces a new dimension of current amplification factors to resolve the contradiction. By adding the amplification factor as an additional parameter, the system can achieve both high current output and fine resolution without being constrained by a single-dimensional current control approach.
2Productivity
If the maximum charging current is increased, then the charging speed is improved, but the circuit scale is increased
Solution Approach 1:
The patent designs multiple charging circuits that share common components such as the current source circuit and control circuit. This multi-functional design allows the system to achieve high charging currents without proportionally increasing the overall circuit scale, as the same control infrastructure serves multiple current levels.
Solution Approach 2:
The patent merges the control functions for multiple charging circuits into a single control circuit that manages all charging circuits. This consolidation reduces the overall circuit complexity while maintaining the capability to deliver high charging currents through multiple parallel paths.
3Adaptability or versatility
If the current mode is switched between two charging circuits, then the current setting flexibility is improved, but unintended large currents may occur during switching
Solution Approach 1:
The patent implements a switching period during mode transitions where the current source circuit output is temporarily set to zero or reduced. This preliminary action prevents unintended large currents from occurring during the switching process by ensuring a safe transition state before the new current mode is fully established.
Solution Approach 2:
The patent introduces a switching period as an intermediary state between two current modes. During this intermediate period, the current source circuit output is controlled to zero or reduced, acting as a mediator that safely transitions the system from one current level to another without causing harmful current spikes.
Data Source
AI summary
A circuit device includes: a current source circuit; a first charging circuit; a second charging circuit; and a control circuit. The control circuit controls, when a current setting value is in a first current range, supply of a first charging current from the first charging circuit to a charging node. The control circuit controls, when the current setting value is in a second current range on a current side higher than the first current range, supply of a second charging current from the second charging circuit to the charging node. The control circuit sets the current source control value such that the output current of the current source circuit is zero or is reduced during a switching period of the current source control value.