Battery Control Circuit Shipment Power Reduction
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Solution Overview
Problem
Conventional charge/discharge control circuits in battery devices experience power consumption issues during shipment, as a discharge current flows via parasitic diodes when a load is connected between external terminals, and the charge/discharge control circuit itself consumes power, leading to reduced battery life.
Innovation Solution
A charge/discharge control circuit with a switch circuit and control circuit that turns off the discharge transistor to interrupt discharge current to an external load, powering down the circuit to reduce current consumption, thereby preventing secondary battery power consumption during shipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge/discharge control circuit remains active to control charge and discharge operations, then the circuit can respond to charge inhibition signals and prevent overcharge/overdischarge, but the circuit consumes power continuously and causes power consumption of the secondary battery during shipment
Solution Approach 1:
The charge/discharge control circuit dynamically changes its operational state based on external conditions. When a signal is detected at the external terminal, the circuit transitions to a power-down state where the discharge control transistor is turned off and discharge current is interrupted. This dynamic state change allows the circuit to maintain reliability during normal operation while reducing power consumption during shipment periods, resolving the contradiction between continuous control functionality and continuous power consumption.
2Ease of operation
If the discharge control transistor remains on to allow discharge current flow, then the load can be powered, but discharge current flows via parasitic diodes during shipment causing power consumption of the secondary battery
Solution Approach 1:
An external terminal is introduced as an intermediary to detect shipment conditions. When a signal is applied to this terminal, it triggers the control circuit to turn off the discharge control transistor, thereby interrupting discharge current through the parasitic diode path. This intermediary mechanism allows the system to distinguish between operational mode (where load power supply is needed) and shipment mode (where power consumption must be prevented), resolving the contradiction between load power supply capability and energy loss during shipment.
3Measurement precision
If the charge/discharge control circuit operates continuously to monitor battery status, then battery voltage and abnormalities can be detected, but the circuit itself consumes power during shipment
Solution Approach 1:
The charge/discharge control circuit implements periodic or conditional operation rather than continuous operation. During shipment (detected via signal at external terminal), the circuit enters a power-down state with minimal power consumption. When a signal is not present (normal operational mode), the circuit becomes active and performs voltage monitoring and abnormality detection. This periodic activation pattern resolves the contradiction between maintaining measurement precision and reducing power consumption during stationary storage periods.
Data Source
AI summary
To solve a problem in that, even after a charge inhibition signal is input from an input terminal and a charge control transistor is turned OFF, if a load is connected between external terminals (EB+, EB−), a discharge current flows, and to solve another problem of power consumption of a charge/discharge control circuit (22), provided is a charge/discharge control circuit for controlling charge/discharge of a secondary battery, the charge/discharge control circuit including: a switch circuit for controlling a current that flows through the charge/discharge control circuit; a control circuit for controlling an operation of the switch circuit; and an input terminal to which a signal for controlling an operation of the charge/discharge control circuit is input from outside. In this way, when a signal is input to the input terminal from outside, the discharge current is interrupted, thereby reducing current consumption of the charge/discharge control circuit.