Switching Power Supply Brown-In Detection Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control ICs for switching power supplies face challenges in accurately detecting brown-in voltage due to capacitive coupling and stray capacitance, leading to erroneous brown-in operations and increased electric power loss.
Innovation Solution
A control device incorporating a voltage dividing circuit, detection circuit, brown-in timer, latch circuit, and logical element that performs a logical AND operation with the pulse width modulation signal to prevent erroneous brown-in operations by latching the output after a predetermined time, thus accurately detecting the brown-in voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brown-in/out detection resistor is always connected to the input voltage terminal to detect brown-in and brown-out, then the detection function is available, but electric power loss increases
Solution Approach 1:
The patent applies periodic action by using the switching operation of the power supply to periodically generate a mask signal that prevents erroneous detection during switching periods. The detection resistor is activated only when needed (during switching periods) rather than continuously, reducing power loss while maintaining detection reliability
2Area of stationary object
If the detection resistor is placed at the vicinity of circuit elements to reduce chip size, then the chip size is reduced, but capacitive coupling generates voltage fluctuations
Solution Approach 1:
The patent introduces a mask signal as an intermediary that mediates between the detection circuit and the voltage fluctuations caused by capacitive coupling. The mask signal blocks erroneous detection during switching periods, allowing the resistor to be placed close to circuit elements without compromising detection accuracy
3Reliability
If a mask signal is generated from the pulse control signal to prevent erroneous switching operation, then erroneous brown-in operation is reduced, but the complexity of the control circuit increases
Solution Approach 1:
The patent applies universality by making the pulse control signal serve multiple functions: it controls the switching operation and simultaneously generates the mask signal for preventing erroneous detection. This multi-functionality reduces the need for separate circuit elements, thereby limiting the increase in circuit complexity
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 effectively prevents erroneous brown-in operations by accurately detecting the brown-in voltage, reducing electric power loss, and ensuring stable switching operations even with stray capacitance present.
Implementation Method 1
a voltage dividing circuit configured to generate a divided voltage by dividing an input voltage
Implementation Method 2
a detection circuit configured to compare the divided voltage with a brown-in detection threshold value
Implementation Method 3
capacitive coupling is generated between the brown-in/out detection resistor and the circuit elements around the brown-in/out detection resistor
Data Source
AI summary
A voltage dividing circuit includes a first register that is supplied with an input voltage and a second resistor, and divides the input voltage to generate a divided voltage. A detection circuit compares the divided voltage with a brown-in detection threshold value, and outputs a first detection signal of H level when the divided voltage is equal to or higher than the threshold value, and outputs the first detection signal of L level when the divided voltage is lower than the threshold value. A brown-in timer outputs a second detection signal after a first predetermined time has elapsed since the time point of the first detection signal. A latch circuit latches an output from the detection circuit in response to the second detection signal. A logical element at least performs logical AND operation of an output of the latch circuit and a PWM signal.