Protection IC Back Gate Voltage Control for Parasitic Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing protection circuits for secondary batteries suffer from increased electric current consumption due to parasitic transistor activation when voltage fluctuations occur, leading to inefficiencies and higher power consumption.
Innovation Solution
A protection integrated circuit that controls a metal-oxide-semiconductor transistor in the power supply path between a secondary battery and a load, utilizing a bias output terminal connected to the back gate of the transistor, a load side terminal, and a load side switch formed on an N-type silicon substrate with two n-channel metal-oxide-semiconductor transistors, which are simultaneously turned on or off based on the battery state to manage voltage and prevent parasitic transistor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional protection circuits use switching elements with back gate voltage control, then the battery can be protected from overcharge and over-discharge, but parasitic transistors are activated during voltage fluctuations causing increased electric current consumption
Solution Approach 1:
The invention changes the voltage parameter applied to the back gate of the switching element. By controlling the back gate voltage to be equal to the source voltage (rather than the conventional drain voltage), the invention prevents parasitic transistor activation while maintaining battery protection functionality. This parameter change eliminates the harmful leakage current path through the parasitic transistor.
2Adaptability or versatility
If the back gate voltage is switched between drain voltage and source voltage to control charging and discharging, then the protection circuit can manage current direction, but voltage fluctuations activate parasitic transistors causing circuit inefficiency
Solution Approach 1:
The invention modifies the back gate voltage parameter to remain equal to the source voltage during both charging and discharging operations. This eliminates the voltage fluctuation between drain and source that activates parasitic transistors, thereby reducing energy loss and improving circuit efficiency while maintaining adaptability in current direction control.
3Ease of operation
If conventional circuits allow voltage fluctuations at the back gate terminal, then the circuit can respond to battery state changes, but this causes parasitic transistor activation and increased power consumption
Solution Approach 1:
The invention changes the back gate voltage parameter from fluctuating between drain and source voltages to maintaining a constant source voltage level. This parameter stabilization prevents parasitic transistor activation while the control circuit continues to respond to battery state changes by adjusting the main switching element's gate voltage, thus maintaining ease of operation without the energy penalty.
Data Source
AI summary
A protection IC includes a bias output terminal connected to a back gate of a MOS transistor, a load side terminal connected to a power supply path between a load and the MOS transistor, a load side switch inserted in an electric current path connecting the bias output terminal and the load side terminal, and a control circuit configured to control the load side switch based on a state of a secondary battery and thereby cause a back gate control signal for controlling a voltage of the back gate to be output from the bias output terminal. The load side switch is formed on an N-type silicon substrate and includes at least two NMOS transistors whose drains are connected to each other, and the control circuit is configured to simultaneously turn on or turn off the two NMOS transistors based on the state of the secondary battery.