Level-Shift Circuit Single Switch Half-Bridge Control
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Solution Overview
Problem
Conventional high-voltage level-shift circuits using two pulse 'set' and 'reset' methods are prone to noise and voltage transients, leading to potential catastrophic failures due to incorrect state verification of the high-side gate driver, and do not guarantee the high-side switch remains OFF when the low-side switch is ON, causing faults in power circuits.
Innovation Solution
A level-shift circuit utilizing a single level-shift switch with an oscillator-generated timing signal to control both high and low side switches, eliminating the need for a latch and integrating dv/dt filter and dead-time functionality into a single circuit, ensuring the high-side switch remains OFF during low-side switch operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional two-pulse set and reset method with latch is used, then level-shifting control is achieved, but circuit complexity increases and reliability decreases due to noise and voltage transients affecting the latch state
Solution Approach 1:
The patent removes the latch component from the conventional set-reset circuit, extracting the problematic element that stores state information. Instead of using a latch that can be corrupted by noise and transients, the invention directly controls the high-side gate driver through level-shifted signals, eliminating the intermediate storage element that causes reliability issues while reducing circuit complexity.
Solution Approach 2:
The patent implements a feedback mechanism where the low-side circuitry receives signals to verify the state of the high-side gate driver. This closed-loop verification ensures that the high-side switch is in the correct state before allowing operation, preventing catastrophic failures due to noise or transients affecting an unlatched circuit.
2Reliability
If two high-voltage level-shift transistors are used for set and reset signals, then level-shifting functionality is provided, but component count and circuit complexity increase
Solution Approach 1:
The patent merges the functions of separate set and reset transistors into a single level-shift switch. By combining these components and using a unified control approach where the low-side circuitry verifies high-side state, the invention reduces component count while maintaining or improving reliability through direct state verification.
3Quantity of substance
If latch is used to store on/off state, then signal storage is achieved, but power losses increase and circuit complexity increases
Solution Approach 1:
The patent extracts and removes the latch component from the circuit, eliminating the source of unnecessary power consumption associated with maintaining latched states. By directly controlling switches through level-shifted signals without intermediate storage, the invention reduces both component count and power losses.
4Ease of operation
If conventional level-shift circuit is used, then high-side control is achieved, but false turn-ons may occur due to noise and voltage transients
Solution Approach 1:
The patent implements feedback verification where low-side circuitry receives and verifies the state of the high-side gate driver before operation. This feedback mechanism detects and prevents false turn-ons caused by noise or voltage transients, ensuring reliable switch state verification while maintaining control functionality.
Data Source
AI summary
A level-shift circuit for use with a half bridge in accordance with an embodiment of the present application includes an oscillator operable to provide a timing signal, a level-shift switch controlled by the timing signal of the oscillator, a high side control circuit operable to provide a high side control signal to a high side switch of the half bridge to control the high side switch and a low side control circuit operable to provide a low side control signal to a low side switch of the half bridge to control the low side switch. The level-shift switch is turned ON when the timing signal is high such that the level-shift switch connects the high side control circuit to ground and the high side control signal stays low to keep the high side switch OFF when the timing signal is high. The low side control circuit provides the low side control signal to turn the low side switch ON a predetermined period of time after the timing signal goes high.