Modulated Power Supply Inductor Decoupling for ToF Sensors
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Solution Overview
Problem
Conventional modulated power supplies for light sources, such as those used in Time-of-Flight sensors, face inefficiencies due to large area requirements and low power efficiency, as well as high turn-off times, particularly when using DC/DC converters and current limiting resistors, and high power losses when employing modulation switches.
Innovation Solution
A modulated power supply system utilizing a DC/DC converter with an inductor and a controller that couples the inductor's terminals via a path outside the inductor during power-off phases to conserve energy and eliminate the need for output capacitors, employing redundant switches for safety and efficient energy reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blocking capacitor is used for decoupling during switching, then the switching function is achieved, but the area required for the capacitor becomes comparatively large
Solution Approach 1:
The patent extracts and eliminates the blocking capacitor from the circuit by using a different switching topology. The modulation switch is moved to the input side of the DC/DC converter, and the inductor is used to perform the decoupling function during switching, thereby removing the need for a large blocking capacitor at the output.
Solution Approach 2:
The inductor in the DC/DC converter is made to serve multiple functions: it performs both energy storage and decoupling during switching operations. This multi-functionality eliminates the need for a separate blocking capacitor, reducing the overall component area.
2Ease of operation
If a current limiting resistor is used, then the current is limited, but the power efficiency becomes comparatively low
Solution Approach 1:
The patent replaces the passive current limiting resistor with an active switching mechanism. The modulation switch on the input side of the DC/DC converter actively controls current flow, eliminating the continuous power dissipation associated with resistive current limiting.
3Loss of time
If a modulation switch is provided between the light source and ground to shunt current, then the turn-off time is reduced, but comparatively high power losses result
Solution Approach 1:
The patent uses the DC/DC converter circuit topology to copy and transfer the energy stored in the inductor to the load during the on-phase, and then efficiently dissipates or recovers the energy during the off-phase through the switching action at the input side, avoiding the high power losses of direct shunting.
4Loss of time
If a modulation switch is provided between the light source and ground, then the turn-off time is reduced, but the power efficiency decreases
Solution Approach 1:
The patent replaces the direct shunting approach with a controlled switching mechanism at the input side of the DC/DC converter. This active control allows for fast turn-off of the light source while managing power losses through the efficient operation of the DC/DC converter during both on and off phases.
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
This approach reduces power consumption and maintains efficient energy storage during off-states, even at high modulation frequencies, thereby enhancing power efficiency and reducing the area required for the power supply.
Implementation Method 1
a first terminal of the inductor to a second terminal of the inductor via a path outside the inductor
Data Source
AI summary
Devices and methods are provided related to modulated power supplies. The device includes an inductor. When a load is to be supplied with power, a terminal of the inductor is coupled to the load. When the load is not to be supplied with power, terminals of the inductor may be coupled with each other.