Field Instrument Current Control for CPU Power Management
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Solution Overview
Problem
Conventional two-wire field instruments face power insufficiency when attempting to use high-performance CPUs due to the requirement of a drive current for alarm driving circuits, leading to either abandoning the alarm circuit or degrading primary processing functions.
Innovation Solution
A current value adjustment mechanism that branches current from a first power supply to a second power supply unit only when secondary functions are needed, using a current control element to manage the flow and ensure sufficient power for both primary and secondary functions without performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high-performance CPU is used for primary processing functions, then processing capability is improved, but power consumption increases causing insufficient power for alarm driving circuit
Solution Approach 1:
The patent applies dynamics by making the current allocation flexible and adjustable rather than fixed. A current control element (transistor) dynamically switches current flow between the CPU and alarm driving circuit based on operational needs. The system transitions between different power distribution states: normal operation (CPU receives full current), alarm state (current redirected to alarm circuit), and startup state (both circuits receive current), thereby resolving the contradiction between providing sufficient power to high-performance CPU and maintaining power availability for secondary functions.
2Reliability
If alarm driving circuit is constantly operated, then secondary function reliability is improved, but primary measurement and control functions are obstructed due to current insufficiency
Solution Approach 1:
The patent implements periodic action by operating the alarm driving circuit only when necessary rather than continuously. The system monitors alarm conditions and activates the alarm driving circuit selectively based on detected abnormal states. During normal operation, the alarm circuit remains inactive and current is fully allocated to the CPU for primary functions. When an alarm condition occurs, current is dynamically redirected to activate the alarm circuit temporarily, then returned to normal distribution after the alarm condition resolves, thus ensuring both primary function productivity and secondary function reliability.
Solution Approach 2:
The patent applies local quality by providing different current allocation states to different parts of the system based on their immediate needs. Instead of uniform continuous power distribution, the system creates localized current pathways: during alarm events, the alarm driving circuit receives concentrated current supply through the controlled current path, while the CPU maintains its operational current. This localized quality approach ensures that each subsystem receives adequate power only when required, resolving the contradiction between alarm reliability and primary function productivity.
3Adaptability or versatility
If current is allocated to alarm driving circuit, then secondary function operation is enabled, but power for primary processing functions is reduced
Solution Approach 1:
The patent resolves this contradiction through dynamic current management using a current control element that adjusts power distribution in real-time based on system state. The transistor acts as a dynamic switch that can rapidly alter current flow paths: during normal operation, the CPU receives full current allocation for optimal processing performance; when alarm functions are needed, the control element dynamically redirects a portion of current to the alarm driving circuit. This dynamic adaptability allows the system to maintain CPU power supply adequacy while enabling secondary function operation when required, achieving both adaptability and power sufficiency.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A current control element (variable resistance element) (12) is provided on a supply path (LA) of the current from a voltage regulator (6) to another voltage regulator (7). An alarm driving circuit (8) is provided on a branch flow path (LB) of the current from the voltage regulator (6) to the voltage regulator (7). When the alarm driving circuit (8) needs to be operated, a current control element controlling unit (3-3) controls the resistance value of the current control element (12) to branch the current (IA) flowing through the supply path (LA) to the branch flow path (LB). In this case, the current (IB) branched to the branch flow path (LB) is set to the amount required to operate the alarm driving circuit (8). Since the sum of the currents (IA, IB) is supplied to the voltage regulator (7) and is the same as the current flowing before the alarm driving circuit (8) is activated, there is no shortage of supplied power to a CPU (3).