Load Driving Device Overcurrent Protection During Reset
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Solution Overview
Problem
Conventional load driving devices lack an overcurrent protection function during the reset period immediately after power is turned on, which can lead to safety issues when the switch element needs to remain in an on state.
Innovation Solution
A load driving device is designed with a logic portion that includes a switch signal generation circuit to maintain the switch element in an on state by default until an external reset is released, an overcurrent protection circuit to forcibly turn off the switch element upon detecting overcurrent, and a latch circuit to restrict the switch signal using the overcurrent detection signal as a trigger during the reset period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switch element is maintained in an on state during the reset period, then the device can operate immediately after power is turned on, but overcurrent protection becomes inactive creating safety risks
Solution Approach 1:
The latch circuit is configured to be active during the reset period (when reset signal is low) to provide overcurrent protection before the main control system is fully operational. This preliminary action ensures safety is established in advance, allowing the switch element to be turned on immediately after power is applied while maintaining protection against overcurrent conditions.
2Reliability
If overcurrent protection is activated during the reset period, then safety is improved, but the device complexity increases due to additional latch circuit requirements
Solution Approach 1:
The latch circuit is integrated into the existing logic portion that controls the switch element, rather than being a completely separate protection system. The latch circuit shares the same control signals and output pathways as the main control logic, allowing overcurrent protection to be combined with the existing control architecture during the reset period.
Solution Approach 2:
The latch circuit serves multiple functions: it provides overcurrent protection during the reset period, works in conjunction with the main control system after reset, and can interface with both the switch element control and overcurrent detection circuits. This multi-functionality reduces the need for entirely separate protection systems.
3Speed
If the switch element remains in on state by default, then operational responsiveness is improved, but the risk of overcurrent damage increases without protection
Solution Approach 1:
The latch circuit is configured to detect overcurrent conditions and immediately restrict the switch signal to turn off the switch element, providing preliminary counter-action against overcurrent damage. This anti-action is prepared in advance during the reset period and activates automatically when overcurrent is detected, preventing damage before it can occur.
Data Source
AI summary
A load driving device, wherein a logic portion for switching on/off a switch element connected to a load includes: a switch signal generation circuit for generating a switch signal so that the switch element is left on by default in a time duration from when power is turned on until an external reset release is performed by a microcomputer; an overcurrent protection circuit for performing, after the external reset release, an output restriction of the switch signal so as to forcibly switch the switch element off in response to an overcurrent detection signal; and a latch circuit for performing, in the time duration from when power is turned on until the external reset release is performed by the microcomputer, an output restriction of the switch signal so as to forcibly switch the switch element off with the overcurrent detection signal serving as a latch trigger.