Driver Circuit Slew Rate Control for Switching Regulator Noise Reduction

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Solution Overview

Problem

Existing driver circuits for switching regulators face challenges in reducing ringing noise and complexity, particularly in controlling slew rate, which is often digital and requires a communication unit, increasing circuit scale and complexity.

Innovation Solution

A driver circuit with a pull-up and pull-down circuit configuration that shares an output node, allowing for slew rate adjustment using threshold voltage, enabling two-step responses to input signals, thereby simplifying the circuit structure and reducing ringing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If variable slew rate control is implemented using a setting table and communication unit, then ringing noise can be reduced, but circuit scale and complexity increase

Engineering Contradiction:

Improveringing noiseVSAvoidcircuit scale

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention extracts the communication unit and setting table from the driver circuit, eliminating the complexity and scale increase while maintaining the ability to control slew rate for reducing ringing noise

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The driver circuit automatically determines the slew rate control based on the switching state of the power transistor without requiring external communication or setting tables, making the circuit self-sufficient and simpler

Inventive Principle:

Principle #25Self-service

2Object-affected harmful factors

If digital slew rate control is implemented, then ringing noise can be reduced, but circuit structure becomes complicated

Engineering Contradiction:

Improveringing noiseVSAvoidcircuit structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention replaces complex digital control mechanisms with a simpler circuit-based approach that uses the inherent switching states to control slew rate, reducing structural complexity while maintaining effectiveness in reducing ringing noise

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If gate resistor is used to control switching, then power consumption increases, but switching control is achieved

Engineering Contradiction:

Improveswitching controlVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The invention changes the control parameter from gate resistor value to slew rate control based on switching states, achieving effective switching control while reducing power consumption by eliminating the need for gate resistors

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10651846B2Driver circuit and switching regulator

Publication Date: 2020.05.12 ROHM CO LTD

AI summary

A driver circuit (DRV1) includes a pull-up circuit (PU1) and a pull-down circuit (PD1) that share an output node (external terminal (T3)). A signal (DI1 (DI2)) input to the pull-up circuit (PU1) and a signal (DI3) input to the pull-down circuit (PD1) are selected in a complementary manner, and the output node outputs an output signal in which rising time and falling time of the signals (DI1 (DI2) and DI3) are adjusted in accordance with on-off operation of the signals. The rising time is adjusted by transistors (M1 and M2) and a resistor (R1), while the falling time is adjusted by transistors (M3, M4 and M5) and a resistor (R2).