Dual-Input Charger Driver Circuit for Safe Capacitor Balancing
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Solution Overview
Problem
In dual input charger apparatuses, the balancing of input capacitors can cause excessive current to flow through high-side switches, potentially damaging them due to shared channels and common nodes, especially in compact device footprints where space for power management technologies is limited.
Innovation Solution
A low-impedance bridge and driver circuit is introduced to provide a safe path for current balancing, using enable switches controlled by a logic circuit to prevent excessive current from flowing through high-side switches by routing it through a controlled path when voltage imbalances occur between input capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple high-side switches share channels with input capacitors connected to a common low-side switch node, then the device footprint is reduced and power management is integrated, but excessive current flows through the high-side switches during capacitor balancing causing potential damage
Solution Approach 1:
A dedicated balancing switch is introduced as an intermediary component between the input capacitors and the common low-side switch node. This balancing switch provides a controlled path for current flow during capacitor balancing operations, preventing excessive current from damaging the high-side switches while maintaining the integrated power management architecture.
Solution Approach 2:
The system dynamically controls the switching states of the high-side switches and balancing switch based on real-time capacitor voltage conditions. During capacitor balancing, the balancing switch is activated to provide a safe current path, while during normal operation, the high-side switches function as intended. This dynamic switching strategy resolves the contradiction between integrated design and component protection.
2Adaptability or versatility
If high-side switches are used to regulate power from multiple charging devices, then charging versatility is improved, but the switches cannot withstand large balancing currents that occur when input capacitors are charged at different rates
Solution Approach 1:
The current path is segmented into separate controlled pathways: one for normal power regulation through high-side switches and another for capacitor balancing through dedicated balancing switches. This segmentation allows each component to operate within its safe current limits while maintaining overall system versatility for multiple charging devices.
Solution Approach 2:
Balancing switches serve as intermediary components that handle the large balancing currents between input capacitors, shielding the high-side switches from exposure to these damaging currents. This intermediary mechanism preserves the current withstanding capability of high-side switches while enabling versatile multi-device charging functionality.
Data Source
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AI summary
A driver circuit includes two high-side switches (111, 112) and a single low-side switch (113), an output inductor (114), and an output capacitor (115). By having multiple high-side switches (111, 112), the driver circuit can regulate power from multiple charging devices. The high-side switches (111, 112) share a channel with an input capacitor (105, 106) for that channel, and the channels are connected to the low-side switch (113) at a common node (1 17). When the capacitor (105, 106) for one of the channels becomes charged quickly, the capacitor (105, 106) of the other channel will balance itself with the charged capacitor. To avoid damaging the high-side switches (111, 112), a low-impedance bridge (118) and driver circuit is connected between the channels.