MCU Wake-Up Circuit for Battery Management System Sleep Mode
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Solution Overview
Problem
The existing methods for waking up a microcontroller unit (MCU) in a battery management system (BMS) sleep mode require user intervention and can lead to over-discharging of batteries since the MCU remains awake even when the battery state of charge is low, as conventional techniques fail to automatically return the MCU to sleep mode after waking up.
Innovation Solution
A device and method that automatically wake up the MCU of a BMS using a wake-up signal generated only once when an external power source is connected, employing a circuit with a first switching unit and a second switching unit, including field effect transistors (FETs), resistors, and capacitors, to control the power supply to the MCU, ensuring the MCU returns to sleep mode after a predetermined time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an external power source is connected to wake up the BMS, then the BMS can be automatically woken up without user intervention, but the BMS may remain awake continuously causing battery over-discharging
Solution Approach 1:
The patent implements periodic action by using a timing circuit (comparator 220, capacitor 230, resistor 220) to generate a pulse signal that activates the wake-up function for a predetermined time period only. When the external power source is detected, the circuit generates a wake-up pulse that turns on the first FET 110, but automatically turns it off after the timing period expires, preventing continuous wake-up and battery over-discharge.
Solution Approach 2:
The patent uses an intermediary timing circuit between the external power source detection and the wake-up signal generation. The comparator 220, capacitor 230, and resistor 220 form an intermediate timing mechanism that processes the external power source signal and converts it into a controlled pulse-width wake-up signal, preventing direct continuous activation.
2Reliability
If the MCU operates continuously to monitor battery state, then accurate battery management is achieved, but battery power is consumed continuously
Solution Approach 1:
The patent implements dynamics by making the MCU operational state changeable between sleep mode and active monitoring mode based on external conditions. The system dynamically transitions from low-power sleep mode to active monitoring only when an external power source is detected, and returns to sleep mode after the predetermined time period, optimizing power consumption while maintaining monitoring capability when needed.
Solution Approach 2:
The patent changes the operational parameter of the MCU from continuous operation to intermittent operation based on external power source detection. The system modifies its working state parameter by entering sleep mode when no external power is present and activating only when external power is detected, reducing power consumption while maintaining functional reliability.
3Device complexity
If a simple wake-up circuit is used, then device complexity is reduced, but the ability to control wake-up duration and prevent over-discharging is limited
Solution Approach 1:
The patent introduces an intermediary timing circuit (comparator 220, capacitor 230, resistor 220) that acts as a mediator between the simple external power source detection and the wake-up control. This intermediary component adds minimal complexity but provides the necessary pulse width control to prevent over-discharging, achieving a balance between simplicity and functionality.
Solution Approach 2:
The timing circuit is designed to be self-regulating, where the capacitor 230 and resistor 220 automatically determine the pulse duration based on their time constant (RC circuit). The circuit serves itself by using the external power source voltage to charge the capacitor, which then naturally discharges through the resistor to generate the timing signal, eliminating the need for additional complex control logic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables automatic waking of the MCU without user intervention and prevents over-discharging by ensuring the MCU returns to sleep mode even when an external power source is connected, optimizing battery management.
Implementation Method 1
a first field effect transistor (FET) wherein a drain terminal of the first FET may be connected to an output terminal of the external power source, a source terminal may be connected to the MCU power generation unit, and a gate terminal may be connected to an output terminal of the external power source
Implementation Method 2
a capacitor having a predetermined capacitance, and a drain terminal of the second FET may be connected to a gate terminal of the first FET, a gate terminal may be connected to an output terminal of the external power source, a resistor having the predetermined resistance value, and a capacitor having the predetermined capacitance
Data Source
AI summary
The present invention provides a device and method for waking up an MCU of a BMS operating in a sleep mode.More specifically, the present invention provides a device and method for waking up an MCU of a BMS that is in a sleep mode automatically by generating a wake-up signal only once, when an external power source is connected, without user's operation.