Discharge Control Circuit Using Two-Stage Gate Drive for Capacitive Loads
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Solution Overview
Problem
Existing methods for suppressing inrush currents in capacitive loads require multiple transistors, increasing cost and complexity, while existing voltage stabilizing circuits do not effectively manage inrush currents during power supply to capacitive loads.
Innovation Solution
A discharge control circuit with a first gate voltage output circuit to maintain constant current, a second gate voltage output circuit to provide a constant voltage, and a switching control circuit to switch between these voltages, reducing the number of transistors needed and effectively managing inrush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first discharge path with a current limiting resistor and a second discharge path without a current limiting resistor are provided with transistors to switch connection/disconnection with the capacitive load, then inrush current can be suppressed during pre-discharge and low resistance power supply during subsequent discharge, but the number of transistors increases leading to higher cost
Solution Approach 1:
The patent merges the functions of two separate transistors (one for pre-discharge path, one for power supply path) into a single transistor. The gate voltage control circuit switches between first gate voltage (for pre-discharge with current limiting) and second gate voltage (for power supply with low resistance), allowing one transistor to perform both discharge path functions, thereby reducing component count and cost while maintaining inrush current suppression capability
Solution Approach 2:
The patent dynamically changes the gate voltage applied to the transistor between two distinct voltage levels: first gate voltage during pre-discharge period to limit current, and second gate voltage during power supply period to reduce resistance. This dynamic voltage switching enables the single transistor to adapt its resistance characteristics to match different operational requirements, effectively replacing multiple static transistor configurations
2Reliability
If multiple transistors are used to provide different discharge paths, then inrush current suppression and low resistance power supply are achieved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple transistor functions into a single transistor device, reducing the bill of materials and assembly complexity. The gate voltage control circuit uses voltage switching to provide different discharge characteristics, eliminating the need for multiple expensive transistor components while maintaining reliable discharge control throughout different operational phases
Data Source
AI summary
The disclosure suppresses an inrush current generated due to discharge of a capacitive load at low cost. A discharge control circuit includes: a first gate voltage output circuit that outputs a first gate voltage supplied to a transistor connected to a capacitive load; a second gate voltage output circuit that outputs a second gate voltage supplied to the transistor; and a switching control circuit that switches supply of the first gate voltage and the second gate voltage to the transistor. The first gate voltage output circuit controls the first gate voltage so that a current flowing through the transistor is constant. The second gate voltage output circuit outputs a voltage at a constant level as the second gate voltage. The switching control circuit performs control to supply the second gate voltage after supplying the first gate voltage to the transistor.