Semiconductor Device Dynamic Clamp Voltage Control
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Solution Overview
Problem
Existing semiconductor devices with dynamic clamp circuits cannot sufficiently lower junction temperature regardless of power supply voltage variations due to constant clamp voltage settings.
Innovation Solution
A semiconductor device with an overvoltage protection circuit that dynamically sets the clamp voltage proportional to the power supply voltage, using a current comparator to control the output transistor and maintain optimal junction temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a constant clamp voltage is set using a diode connected between gate and drain of the n-channel power MOS transistor, then the circuit structure is simple, but the junction temperature cannot be sufficiently lowered regardless of power supply voltage variations
Solution Approach 1:
The clamp voltage is changed from a constant value to a dynamic value that varies in proportion to the power supply voltage. This is achieved by using a buffer amplifier to generate a clamp voltage signal that is proportional to the power supply voltage, allowing the clamp voltage to adapt dynamically to different operating conditions and sufficiently lower the junction temperature across all power supply voltage levels.
Solution Approach 2:
The clamp voltage parameter is changed from a fixed constant value to a variable value that scales with the power supply voltage. By making the clamp voltage proportional to the power supply voltage through the buffer amplifier circuit, the system can maintain optimal temperature control across varying operating conditions.
2Temperature
If the clamp voltage is set to a constant value, then the circuit design is straightforward, but it is not possible to reduce the junction temperature to a sufficiently low level under varying power supply conditions
Solution Approach 1:
The overvoltage protection circuit uses a buffer amplifier to dynamically generate a clamp voltage that is proportional to the power supply voltage. This dynamic approach allows the circuit to maintain effective temperature control while adding only moderate complexity through the buffer amplifier stage.
Solution Approach 2:
The buffer amplifier circuit provides feedback control by continuously monitoring the power supply voltage and adjusting the clamp voltage accordingly. This feedback mechanism ensures that the clamp voltage remains proportional to the power supply voltage, enabling effective junction temperature control without requiring complex external adjustment circuits.
3Loss of time
If a constant clamp voltage is used, then the protection circuit is simple to implement, but the clamp operation time increases and chip area is not optimized
Solution Approach 1:
The dynamic clamp voltage that varies in proportion to the power supply voltage enables faster and more efficient clamp operations. By adapting the clamp voltage to the actual operating conditions, the circuit can quickly respond to overvoltage events and return to normal operation, reducing clamp operation time and optimizing chip area utilization.
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 lowers junction temperature by varying the clamp voltage in proportion to the power supply voltage, reducing heat generation and preventing transistor breakdown during power surges, while optimizing chip area and reducing clamp operation time.
Implementation Method 1
an overvoltage protection circuit that controls a conductive state of the output transistor when an output voltage reaches a clamp voltage
Implementation Method 2
a high-side switch or a low-side switch that switches between supply and cutoff of a current to a load circuit
Implementation Method 3
when a current supplied to the load circuit is cut off by the IPD, an output voltage that is generated at a node that connects the IPD and the load circuit becomes higher than a power supply voltage
Data Source
AI summary
A semiconductor device according to related art has a problem that a clamp voltage that clamps an output voltage cannot adaptively vary in accordance with a power supply voltage, and it is thus not possible to reduce heating of a semiconductor chip to a sufficiently low level. According to one embodiment, a semiconductor device includes a drive circuit (10) that controls on and off of an output transistor (13) and an overvoltage protection circuit (12) that controls a conductive state of the output transistor (13) when an output voltage Vout reaches a clamp voltage, and the overvoltage protection circuit (12) has a circuit structure that sets the clamp voltage to vary in proportion to a power supply voltage VDD.