IMON Generation Circuit Auto-Inductance Detection

Solution Overview

Problem

Existing power stage systems face challenges in accurately monitoring current due to variations in inductance with operating current and temperature, requiring complex trimming processes and external pin settings for inductance value adjustment.

Innovation Solution

An auto-inductance-detection architecture is implemented in the IMON generation circuit, which includes a variable resistor and close-loop control to automatically adjust resistance and perform auto-inductance detection, simplifying the trimming process and providing temperature and PVCC compensation for improved accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual trimming process and external pin settings are used for inductance value adjustment, then current monitoring accuracy can be improved, but device complexity and ease of operation deteriorate

Engineering Contradiction:

Improvecurrent monitoring accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs self-calibration by automatically detecting inductance values and adjusting compensation parameters without external intervention. The microcontroller executes calibration routines that measure actual inductor characteristics and configure compensation circuitry accordingly, eliminating manual trimming processes and external pin settings while maintaining high measurement precision

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system dynamically changes compensation parameters based on detected inductance variations. By measuring actual inductor parameters and adjusting compensation values in real-time, the system adapts to different operating conditions and inductance values without requiring complex manual configuration or external adjustment pins

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If manual trimming process and external pin settings are used for inductance value adjustment, then current monitoring accuracy can be improved, but ease of operation deteriorates

Engineering Contradiction:

Improvecurrent monitoring accuracyVSAvoidease of operation

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The system performs self-calibration by automatically detecting inductance values and adjusting compensation parameters without external intervention. The microcontroller executes calibration routines that measure actual inductor characteristics and configure compensation circuitry accordingly, eliminating manual trimming processes and external pin settings while maintaining high measurement precision

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system performs automatic calibration during initialization or startup phase, detecting inductance values and configuring compensation parameters before normal operation begins. This preliminary automatic configuration eliminates the need for manual trimming during operation and simplifies the user experience while ensuring accurate current monitoring from the start

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If inductance variations with operating current and temperature are not considered, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improvecircuit complexityVSAvoidIMON accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system dynamically changes compensation parameters based on detected inductance variations. By measuring actual inductor parameters and adjusting compensation values in real-time, the system adapts to different operating conditions and inductance values without requiring complex manual configuration or external adjustment pins

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system implements feedback mechanisms that continuously monitor operating conditions and adjust compensation parameters accordingly. By measuring actual current and comparing with expected values, the system detects inductance variations due to temperature or current effects and automatically compensates, maintaining high measurement precision without excessive complexity

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11233454B2Power stages and current monitor output signal (IMON) generation circuit

Publication Date: 2022.01.25 ALPHA & OMEGA SEMICON INT LP

AI summary

Apparatus and associated methods relate to implementing an auto-inductance-detection architecture to reconstruct current monitor output (IMON) when a low-side switch in a power stage is on. In an illustrative example, an IMON generation circuit may include a variable resistor. A close loop control (e.g., OTA, switches, and variable resistor) may be configured to adjust a resistance value of the variable resistor automatically. The IMON generation circuit may also include a low pass filter coupled to a switching node of the power stage to receive a corresponding signal and provide a DC value. The difference between the corresponding signal and the DC value may be configured to enable or disable the close loop control. By providing the close loop control, the IMON generation circuit may advantageously perform auto-inductance detection (AID) and provide a more accurate IMON reconstruction method.