Charge Discharge Control Circuit Overcurrent Cancel Terminal
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Solution Overview
Problem
Battery devices with small load impedance fail to resume discharging after discharge overcurrent detection due to the voltage at the overcurrent detection terminal not falling below the discharge overcurrent detection voltage, preventing the discharge overcurrent cancel circuit from switching to a second voltage value and thus not canceling the discharge overcurrent state effectively.
Innovation Solution
A charge/discharge control circuit configuration with a separate overcurrent cancel terminal allows the discharge overcurrent cancel circuit to switch to a second voltage value when the voltage at the overcurrent cancel terminal falls below the discharge overcurrent cancel voltage, ensuring discharging resumes even with small load impedance by providing a dedicated path for the overcurrent cancel terminal to the external terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage at the overcurrent detection terminal is used to detect discharge overcurrent, then discharge overcurrent can be detected, but when the load impedance is small, the voltage does not fall below the discharge overcurrent detection voltage after the abnormal event, preventing discharging from resuming
Solution Approach 1:
The patent introduces an overcurrent cancel terminal as an intermediary element that allows external voltage application to force the discharge overcurrent cancel circuit to switch to the second voltage value. This mediator bypasses the stuck voltage comparison at the overcurrent detection terminal, enabling the discharge control FET to be turned on and discharging to resume even when the load impedance remains small.
2Ease of operation
If a discharge overcurrent cancel circuit is added to resume discharging, then discharging can be canceled, but the circuit complexity increases
Solution Approach 1:
The overcurrent cancel terminal is designed with multi-functionality: it serves as an external control interface for forcing the discharge overcurrent cancel circuit to switch, while also being connectable to external terminals for automated control. This universal design allows the same terminal to serve multiple purposes without requiring additional dedicated terminals or circuits.
3Reliability
If two charge/discharge control devices are used to enhance safety, then safety is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the functionality of multiple charge/discharge control devices by allowing the overcurrent cancel terminal of the secondary cell-side control circuit to be controlled by external voltage from the first control circuit's output. This merging approach enables coordinated operation between multiple control devices, achieving enhanced safety through inter-circuit communication and shared control functions, thereby reducing overall system complexity.
Data Source
AI summary
Provided is a charge/discharge control circuit for controlling charging and discharging of a secondary cell. The charge/discharge control circuit includes a positive power supply terminal and a negative power supply terminal configured to monitor a voltage of the secondary cell, a charge control signal output terminal from which a charge control signal is output, the charge control signal controlling stopping and allowing charging of the secondary cell, a discharge control signal output terminal, an overcurrent detection terminal, an overcurrent cancel terminal, an external voltage input terminal provided separately from the overcurrent cancel terminal, a discharge overcurrent detection circuit connected to the overcurrent detection terminal, to which a discharge overcurrent detection voltage is set, and a discharge overcurrent cancel circuit connected to the overcurrent cancel terminal, to which a discharge overcurrent cancel voltage is set.