Semiconductor High-Side Drive Circuit Noise Immunity
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Solution Overview
Problem
In semiconductor devices with totem-pole-connected power devices, external noise can cause the high-side power device to fail to turn off at the correct time, leading to potential short circuits and overcurrents, which existing solutions do not completely prevent, especially when dead time is short or high-side potential changes are significant.
Innovation Solution
A semiconductor device with a high-side drive circuit, high-side potential detection circuit, low-side drive circuit, overcurrent detection circuit, and overcurrent detection determination circuit that detects changes in high-side potential and current, and invalidates the overcurrent detection signal to prevent premature low-side power device turn-on, ensuring reliable high-side power device turn-off and preventing overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a second off signal is outputted a determined time after a first off signal to ensure high-side power device turn-off, then the high-side power device can be turned off reliably, but new external noise may be generated during the determined time interval causing malfunction
Solution Approach 1:
The high-side potential determination circuit monitors the high-side potential in advance before the reset signal transmission, and outputs an event signal when potential changes are detected that would impede reset signal transmission. This preliminary detection allows the pulse generation circuit to proactively regenerate the reset signal before the original reset timing, preventing the malfunction before it occurs.
Solution Approach 2:
The high-side potential determination circuit provides feedback about the high-side potential status to the pulse generation circuit. When the feedback indicates that potential changes are impeding reset signal transmission, the pulse generation circuit adjusts its operation to regenerate the reset signal, creating a closed-loop control system that adapts to changing conditions.
2Productivity
If dead time is set short to improve switching speed and productivity, then switching efficiency increases, but external noise more easily causes the high-side power device to fail turning off, leading to overcurrent
Solution Approach 1:
The high-side potential determination circuit performs preliminary monitoring of the high-side potential during the dead time interval. When potential changes indicating noise interference are detected, the circuit outputs an event signal that triggers reset signal regeneration, ensuring the high-side power device turns off reliably even when dead time is short and the system is more vulnerable to noise.
3Reliability
If overcurrent detection is activated to protect against overcurrent, then device protection is improved, but false overcurrent detection occurs when high-side power device fails to turn off due to noise, causing unintentional operation cessation
Solution Approach 1:
The high-side potential determination circuit performs preliminary detection of potential changes that would prevent proper high-side power device turn-off. By outputting an event signal in advance, it enables the pulse generation circuit to regenerate the reset signal before overcurrent can occur, preventing false overcurrent detection and unnecessary operation cessation.
Solution Approach 2:
The system takes preliminary anti-action by detecting and correcting the root cause (failure to turn off due to noise) before it leads to the harmful effect (overcurrent). The event signal mechanism prevents the conditions that would trigger false overcurrent detection, rather than merely responding to overcurrent after it occurs.
4Ease of operation
If level shift circuit is used to drive high-side power device, then high-side drive capability is improved, but external noise causes potential changes that impede reset signal transmission, preventing proper turn-off
Solution Approach 1:
The high-side potential determination circuit provides feedback about the high-side potential status to the pulse generation circuit. When potential changes are detected that would impede reset signal transmission through the level shift circuit, the feedback triggers regeneration of the reset signal, ensuring reliable high-side power device turn-off despite noise interference.
Solution Approach 2:
The high-side potential determination circuit acts as an intermediary between the noisy high-side potential environment and the pulse generation circuit. It translates potential changes into event signals that trigger appropriate reset signal regeneration, mediating the interaction between the level shift circuit and control logic.
Data Source
AI summary
In a semiconductor device, a high-side potential determination circuit outputs an event signal when a high-side reference potential detected by a high-side potential detection circuit rises. If at that time an input logic signal for controlling a high side is at a low (L) level, a pulse generation circuit regenerates a reset signal for a high-side drive circuit. When the input logic signal for controlling the high side is at the L level and the event signal is inputted, an overcurrent detection determination circuit makes an overcurrent detection signal from an overcurrent detection circuit invalid. When the event signal is not inputted, the overcurrent detection determination circuit makes the overcurrent detection signal valid.