Dual Linear Voltage Regulator for Hearing Aid Power Stability
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Solution Overview
Problem
Hearing aids require a stable power supply to maintain proper operation, but existing voltage regulators struggle to provide immediate and precise voltage after battery power is applied, especially when using rechargeable batteries with limited voltage, leading to potential noise, distortion, and system crashes.
Innovation Solution
A dual linear voltage regulator system is implemented, where a first voltage regulator provides immediate power and a second, more precise regulator takes over after a predetermined time or voltage condition is met, with a discharging circuit to manage the transition and prevent power surges, ensuring a stable output voltage within 2% of the nominal supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single linear voltage regulator is used, then the circuit is simple, but the voltage stability and precision cannot be maintained within 2-5% of nominal supply voltage
Solution Approach 1:
The voltage regulator system is divided into two separate linear voltage regulators instead of using a single regulator. The first regulator provides immediate power with acceptable precision, while the second regulator takes over after startup to provide high-precision voltage regulation. This segmentation allows each regulator to be optimized for its specific function, resolving the contradiction between reliability and complexity.
2Measurement precision
If a band-gap voltage reference is used, then voltage precision is improved, but the reference voltage (1.25V) exceeds the battery voltage (1.1-1.3V) and cannot be directly powered
Solution Approach 1:
The system performs preliminary action by using the first linear voltage regulator to establish a stable power supply before the band-gap voltage reference and second regulator can be activated. The first regulator operates during the startup phase to provide sufficient voltage headroom, enabling the band-gap reference to eventually reach its operating voltage. This preliminary power establishment resolves the power supply compatibility issue.
Solution Approach 2:
The system dynamically switches between two voltage regulator configurations based on the startup phase. During initial startup, the first regulator is active with the band-gap reference disabled. After a predetermined time or voltage condition is met, the system transitions to the second regulator with the band-gap reference active. This dynamic adaptation allows the system to overcome the voltage mismatch constraint.
3Use of energy by moving object
If the first voltage regulator is disconnected immediately when the second regulator is activated, then power consumption is reduced, but voltage drops and noise may occur
Solution Approach 1:
The discharging circuit provides beforehand cushioning by gradually discharging the capacitor connected to the first voltage regulator's output. This gradual discharge prevents sudden voltage drops when the first regulator is disconnected. The capacitor acts as a buffer that maintains voltage stability during the transition period, allowing the first regulator to be safely deactivated without causing noise or instability in the hearing aid circuitry.
4Use of energy by moving object
If a voltage doubler circuit with clock generator is used to provide higher supply voltage, then the band-gap reference can be powered, but the oscillator requires 2-3 milliseconds to start up and draws large power
Solution Approach 1:
Instead of using a complex voltage doubler circuit with clock generator, the system segments the power supply function into two simple linear voltage regulators. The first regulator provides immediate power during startup without requiring oscillators or complex circuits. This segmentation eliminates the 2-3 millisecond startup delay and large power consumption associated with voltage doubler circuits, while still enabling the band-gap reference to operate through the second regulator after startup.
Data Source
AI summary
An apparatus for a hearing device includes a first voltage regulator with an output terminal; a first voltage reference; a second voltage regulator with an output terminal; a switching element; and a decoupling element; wherein the switching element and the decoupling element are operatively between the first voltage reference and the first voltage regulator; wherein the output terminal of the first voltage regulator shares a same electrical node as the output terminal of the second voltage regulator; and wherein the first voltage regulator is configured to provide a first output voltage in response to applied battery power, the second voltage regulator is configured to provide a second output voltage if a certain condition is fulfilled, and the switching element is configured to disconnect the first voltage reference from the decoupling element if the condition is fulfilled.