Flash Driver Current Limiting via Voltage Drop Feedback
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Solution Overview
Problem
Current flash drivers in mobile devices face challenges in regulating load current effectively under changing temperature conditions, leading to reduced efficiency and potential system collapse due to battery limitations.
Innovation Solution
A flash driver system comprising a DC/DC converter and an adjustable current source, controlled by multiple units to maintain constant output current through temperature compensation, using detected voltage drops to adjust the conversion and compliance voltage, ensuring consistent flash performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flash driver operates during main flash phase after diagnostic flash, then the device heats up and efficiency reduces, but the output current must be reduced due to battery limitation
Solution Approach 1:
The patent performs a diagnostic flash before the main flash to pre-evaluate battery conditions and predict temperature rise effects. Based on this preliminary assessment, the system determines appropriate current parameters for the subsequent main flash, allowing it to maintain optimal current levels without causing system collapse.
Solution Approach 2:
The system measures the actual temperature rise during operation and uses this feedback to adjust the flash current dynamically. The control unit monitors temperature conditions and modifies the current output accordingly, ensuring stable operation while maintaining flash performance within battery safety limits.
2Measurement precision
If the system uses a diagnostic flash to evaluate battery conditions, then parameters can be set for main flash, but accurate prediction of temperature rise influence is difficult
Solution Approach 1:
The patent changes the approach from attempting to predict temperature rise to directly measuring it. The system uses temperature sensors to obtain actual temperature data during operation, converting an unpredictable parameter into a measurable one, thereby achieving accurate current adjustment without complex prediction algorithms.
3Productivity
If the flash current is increased to maintain output during main flash, then flash quality improves, but the battery may enter critical state and cause system collapse
Solution Approach 1:
Before executing the main flash, the system performs a diagnostic flash to assess the battery's current capacity and temperature conditions. Based on this preliminary evaluation, the control unit determines the maximum safe current that can be drawn during the main flash without causing battery critical state or system collapse.
Solution Approach 2:
The system continuously monitors battery voltage and temperature during flash operation and uses this feedback to dynamically adjust the flash current. When temperature rise or voltage drop indicates approaching battery limits, the system automatically reduces current to maintain safety margins while preserving flash functionality.
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 constant load current under varying temperatures, improving flash quality and preventing system resets by accurately evaluating battery conditions and adjusting power delivery.
Implementation Method 1
a dc/dc converter (100) having a first input to receive an input voltage and an output to supply an output voltage
Implementation Method 2
an adjustable current source (102) connected between the output and a load terminal
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A flash driver to limit a load current for a flash comprises a dc/dc converter (DCDC) having a first input (IN1) to re ceive an input voltage (Vin) and an output (OUT) to supply an output voltage (Vout). The dc/dc converter is designed to convert the input voltage (Vin) to the output voltage (Vout). Furthermore the flash driver has an adjustable current source (Iadj) connected between the output (OUT) and a load terminal (LT). A first control unit (CTRL_1) is connected to the first input (IN1) and coupled to the adjustable current source (Iadj), and is designed to compare the input voltage (Vin) to a threshold (Vth) and, if the comparison indicates the input voltage (Vin) being smaller than the threshold value (Vth), adjust the adjustable current source (Iadj) such that the input voltage (Vin) is equal or greater than the threshold value (Vth). A second control unit (CTRL_2) is coupled to the adjustable current source (Iadj) and the dc/dc converter (DCDC) and is designed to detect a voltage drop over the adjustable current source (Iadj) and to set the dc/dc converter (DCDC) to control the conversion of input voltage (Vin) to the output voltage (Vout) depending on the detected voltage drop.