Flash Memory Bleeder Circuit for Residual Voltage Discharge
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Solution Overview
Problem
Electronic devices, such as Flash memory modules, experience unpredictable behavior due to residual voltages on supply lines after power removal, leading to undefined states, especially when voltages near or below the transistor threshold voltage, causing persistent undefined states and potential failures during restart.
Innovation Solution
A charge bleeder circuit is introduced, comprising a resistor, transistors, and a control circuit with a coupling capacitor, which automatically detects and manages voltage levels to bleed off residual charges when the voltage falls below the transistor threshold, ensuring a defined state by allowing or inhibiting current flow between the supply line and ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power is removed from the supply line, then energy consumption is reduced, but residual voltage remains on the supply line causing unpredictable device states
Solution Approach 1:
The circuit performs preliminary action by automatically discharging residual voltage from the supply line before the device enters an undefined state. The control circuit detects when voltage drops to threshold levels and activates the discharge path through the second transistor, ensuring the supply line is fully discharged before the device could potentially wake up in an undefined state.
Solution Approach 2:
The circuit implements self-service by using the device's own internal components (control circuit, transistors, and coupling capacitor) to monitor and discharge its own supply line voltage. The control circuit continuously monitors the supply line voltage and automatically activates the discharge path when needed, without requiring external intervention.
2Reliability
If an off-chip controller is used to connect the supply line to ground, then residual voltage can be discharged, but device complexity and external dependencies increase
Solution Approach 1:
The circuit merges the voltage discharge function with the existing on-chip control circuitry. The control circuit that already exists for other device functions is utilized to also control the discharge transistor, combining multiple functions into a single integrated circuit rather than adding separate external components.
Solution Approach 2:
The coupling capacitor acts as an intermediary element that transmits the control signal from the control circuit to the gate of the second transistor. This capacitor enables the control signal to pass through while blocking DC components, facilitating the activation of the discharge path without direct electrical connection between the control circuit and transistor gate.
3Reliability
If the discharge circuit operates continuously, then supply line voltage is maintained below threshold, but device functionality is inhibited during normal operation
Solution Approach 1:
The discharge circuit operates periodically rather than continuously. The control circuit monitors the supply line voltage and only activates the discharge transistor when the voltage drops to or below the threshold voltage. During normal operation when voltage is above threshold, the discharge path remains inactive, allowing the device to function normally.
Solution Approach 2:
The control circuit uses feedback from the supply line voltage level to control the discharge transistor. The control circuit continuously monitors the voltage on the supply line and adjusts the discharge path activation accordingly - activating when voltage is low and deactivating when voltage is sufficient, creating a closed-loop control system.
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
The solution effectively manages voltage levels to maintain a valid state in electronic devices by automatically bleeding off residual charges, preventing undefined states and ensuring reliable device operation upon restart.
Implementation Method 1
a gate coupled to an output of a control circuit via a coupling capacitor
Implementation Method 2
output a voltage that causes a channel to open in the second transistor allowing current to flow between the voltage supply line and ground
Data Source
AI summary
Embodiments of the present disclosure include an apparatus. The apparatus includes a flash memory with a device threshold voltage for an on/off state, a sense circuit, a decoupling capacitor, and a bleeder circuit. The sense circuit is configured to sense a voltage level of a voltage supply line. The bleeder circuit is configured to bleed a remaining charge available on the decoupling capacitor. The sense circuit is configured to determine a state of the flash memory based on the voltage level of the voltage supply line. The bleeder circuit is configured to bleed the decoupling capacitor in an off state and to preserve the remaining charge available in an on state.