Level Shifter Circuit for Negative-Potential LED Dimming
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Solution Overview
Problem
Conventional semiconductor devices operating with negative potentials, such as LED drivers and switching power supplies, face challenges in efficiently managing the level shifting and analog dimming of output signals due to the need for precise control over negative potential references.
Innovation Solution
A level shifter is integrated into the semiconductor device, which includes a current output amplifier and resistors to perform accurate level shifting from a ground potential to a negative potential, enabling precise control of analog dimming signals and ensuring stable operation of the switching power supply and LED load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional level shifter is used in semiconductor devices operating with negative potentials, then the device can interface between ground potential and negative potential circuits, but the analog dimming control precision deteriorates due to difficulty in accurately controlling the current setting signal
Solution Approach 1:
The patent introduces an operational amplifier as an intermediary component in the level shifter circuit. The operational amplifier accurately controls the current setting signal by amplifying the difference between the analog dimming signal and the feedback signal, thereby achieving precise analog dimming control while interfacing between ground potential and negative potential circuits.
Solution Approach 2:
The patent changes the electrical potential reference parameter by shifting from ground potential to negative potential reference. The level shifter circuit uses the operational amplifier to adjust and stabilize the current setting signal at the negative potential level, enabling accurate analog dimming control in the negative potential domain.
2Manufacturing precision
If the level shifter uses complex circuitry to achieve accurate level shifting, then the analog dimming control improves, but the manufacturing cost and device complexity increase
Solution Approach 1:
The operational amplifier in the level shifter circuit serves multiple functions: it performs level shifting between ground and negative potentials, provides voltage amplification, and enables precise current control. This multi-functionality achieves high level shifting accuracy while avoiding the need for additional dedicated components, thereby simplifying manufacturing.
3Stability of the object's composition
If the current setting signal is not accurately controlled, then the circuit design is simpler, but the LED dimming linearity and stability deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the output current is sensed and fed back to the operational amplifier. The operational amplifier compares the feedback signal with the analog dimming signal and adjusts the current setting signal accordingly, ensuring stable and linear LED dimming control while maintaining a relatively simple circuit structure.
Data Source
AI summary
A level shifter includes a current output amplifier configured to output a first output current and a second output current through first and second output terminals thereof, respectively, a first resistor configured to be connected between each of an inverted input terminal and the first output terminal of the current output amplifier and an application terminal of a ground potential, and a second resistor configured to be connected between the second output terminal of the current output amplifier and an application terminal of a negative potential lower than the ground potential. A first analog signal referenced to the ground potential is accepted at a non-inverted input terminal of the current output amplifier, and a second analog signal referenced to the negative potential is outputted through one terminal of the second resistor.