Switching Control Circuit for Sense Resistor Short Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switching control devices lack protection against sense resistor short circuits, which can lead to damage or destruction of switching elements due to missed turn-off opportunities and excessive current flow.
Innovation Solution
A switching control device with a control circuit that generates a drive control signal to turn on and off a switching element based on a sense voltage, incorporating a protection mechanism to turn off the element if the sense voltage does not reach a predetermined threshold within a predetermined time, preventing damage from sense resistor short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current control method is used to determine turn-off time based on sense voltage, then switching element can be controlled efficiently, but if sense resistor is short-circuited the control fails and switching element is damaged
Solution Approach 1:
The control circuit performs preliminary actions by setting a predetermined time period and threshold voltage before the actual switching operation. During current control, if the sense voltage does not reach the threshold within the predetermined time, the control circuit proactively turns off the switching element, preventing potential damage from sense resistor short circuits while maintaining efficient normal operation.
2Ease of operation
If output terminal is short-circuited to supplied power or ground, then excessive current flows through transistors, but no protection mechanism exists to prevent device destruction
Solution Approach 1:
The control circuit continuously monitors the voltage at the output terminal during switching operations. When the output terminal is short-circuited to supplied power or ground, the feedback mechanism detects the abnormal voltage condition and triggers protective action by turning off the switching element, preventing excessive current from destroying the transistors while allowing full driving capability during normal operation.
Data Source
AI summary
A direct-current voltage is applied to a series circuit composed of a switching transistor, a sense resistor, and a coil. A control circuit is configured to be capable of performing current control in which the control circuit, after turning on the switching transistor, determines a turn-off time point of the switching transistor based on a sense voltage appearing across the sense resistor, and to turn off the switching transistor during the current control if, despite a predetermined time having passed after the switching transistor being turned on, the sense voltage does not reach a predetermined threshold voltage.