Constant Current LED Drive Circuit With Zero Standby Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing constant current driving circuits for photoelectric smoke alarms face challenges in maintaining a constant current and luminous intensity over varying power supply voltage and temperature ranges, with existing solutions either consuming high power, occupying large areas, or requiring additional components that increase costs and electromagnetic interference.
Innovation Solution
A compact constant current driving circuit integrated into a chip, comprising a reference voltage source module, linear voltage regulator module, level conversion module, and current mirror module, with a first NMOS transistor, which ensures a constant current and luminous intensity by eliminating voltage coefficients and reducing standby power consumption, while allowing separate control of the linear voltage regulator for reduced energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If built-out linear voltage regulators are used to maintain stable voltage, then voltage stability is improved, but static power consumption increases and cost increases
Solution Approach 1:
The linear voltage regulator is controlled to operate periodically rather than continuously. The control circuit enables the voltage regulator to work only when needed (when voltage drops below a threshold) and disables it during normal operation, thereby reducing static power consumption while maintaining voltage stability when required
Solution Approach 2:
A feedback control mechanism is implemented where the output voltage is monitored and compared against a reference voltage. The control circuit adjusts the linear voltage regulator's operation based on this feedback, enabling it to activate only when voltage stabilization is needed, thus reducing unnecessary power consumption
2Adaptability or versatility
If built-in DC-DC boost voltage modules are used, then voltage conversion capability is improved, but chip area increases and EMI increases
Solution Approach 1:
The voltage regulation function is merged with the existing linear voltage regulator architecture rather than using a separate DC-DC boost module. The control circuit integrates with the regulator to provide adaptive voltage stabilization, achieving voltage conversion capability while occupying minimal chip area and avoiding EMI issues associated with switching circuits
3Device complexity
If single chip machine with discrete devices is used, then integration is improved, but PCB area increases
Solution Approach 1:
Multiple functional blocks including the reference voltage source, control circuit, and linear voltage regulator are merged into a single integrated chip. This consolidation eliminates the need for discrete components and PCB mounting, thereby reducing PCB area while maintaining functional integration
Solution Approach 2:
The integrated chip provides multiple functions including voltage reference generation, voltage regulation control, and actual voltage stabilization in a single device. This multi-functionality reduces the overall system complexity and PCB space requirements compared to using separate discrete components for each function
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution maintains a constant current and consistent luminous intensity over a wide temperature range without voltage coefficients, reduces power consumption, and occupies less PCB area, meeting timing sequence requirements and reducing unnecessary energy usage.
Implementation Method 1
a reference voltage source module (1), a linear voltage regulator module (3)
Implementation Method 2
A constant current I1 that does not vary with the power supply voltage, temperature and time is provided to the infrared light emitting diode D1
Implementation Method 3
generating infrared light with constant luminous efficiency
Implementation Method 4
When smoke enters into the optical labyrinth, the photodiode D2 receives the infrared light by refraction and reflection, thereby generating a photocurrent I0
Implementation Method 5
a voltage of the chip and an anode of the infrared light emitting diode are maintained stable
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A constant current driving circuit and a corresponding photoelectric smoke alarm circuit are provided. The constant current driving circuit includes a reference voltage source module (1), a linear voltage regulator module (3), a level conversion module (2), a current mirror module (4) and a first NMOS transistor. The linear voltage regulator module (3) may control turning on and turning off thereof according to actual requirements, thus electrical energy loss may effectively be reduced for some periodically used devices. The constant current driving circuit and the corresponding photoelectric smoke alarm circuit may provide a constant current source, so that auxiliary output performance remains stable within a full temperature range, a certain timing sequence requirement is met, no standby power is consumed when not working, performance is stable, power consumption is low, and application range is wide.