Driving Device Current Sense Circuit Logic Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional driving devices for light-emitting elements, such as LED flasher lamp drivers, face issues with indefinite initial lighting periods due to the lack of precise control over the output current supply, especially when the flasher switch is operated externally.

Innovation Solution

A driving device incorporating a transistor, logic circuit, and current sense circuit that enables on/off control of the output current at predetermined periods, with the logic circuit suspending control and resetting the period when the output current falls below a threshold, ensuring consistent blinking of flasher lamps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional driving devices are used without current monitoring, then the device complexity is reduced, but the reliability of intermittent driving control deteriorates due to indefinite initial lighting periods

Engineering Contradiction:

Improvereliability of intermittent driving controlVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The current sense circuit continuously monitors the output current and provides feedback to the logic circuit. When the output current drops below a threshold during the on-period, the logic circuit receives this feedback signal and responds by resetting the period counter, ensuring reliable intermittent driving control through closed-loop current monitoring

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The logic circuit performs multiple functions: it controls the on/off switching of the transistor, monitors the period timing, detects current threshold violations, and resets the period counter when needed. This multi-functionality improves reliability without proportionally increasing device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If the logic circuit continuously monitors output current during on-period, then the precision of timing control is improved, but the use of energy increases

Engineering Contradiction:

Improveprecision of timing controlVSAvoiduse of energy by logic circuit

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The current sense circuit is enabled only during the on-period of the transistor and disabled during the off-period. This periodic operation allows precise timing control and current monitoring when needed, while reducing energy consumption by halting monitoring during periods when the transistor is already off

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system applies monitoring and control actions only partially - specifically during the on-period when current flow occurs and timing reset may be needed. This partial action achieves sufficient measurement precision without the excessive energy cost of continuous monitoring throughout entire cycles

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11134548B2Driving device

Publication Date: 2021.09.28 ROHM CO LTD

AI summary

A driving device includes, for example: an output terminal; a transistor configured to generate an output current to the output terminal; a logic circuit configured to perform on/off control of the transistor at a predetermined period; and a current sense circuit configured to sense the output current. The current sense circuit is configured to be enabled during an on-period of the transistor. The logic circuit is configured to suspend the on/off control and reset the period when the output current becomes lower than a first threshold value during the on-period.