Multifunction Pin for Switched Mode Power Supply Brownout Detection

Solution Overview

Problem

Conventional switched mode power supplies require an extra pin for brownin and brownout detection, increasing the pin count and cost of integrated circuits.

Innovation Solution

A multifunction pin (pin COMP) is used to perform both brownin and brownout detection, eliminating the need for an additional pin by configuring it as an output node of an error amplifier during normal operation and utilizing path switches and resistors to manage compensation capacitor charging and discharging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an extra pin is added for brownin and brownout detection, then detection functionality is improved, but pin count and cost increase

Engineering Contradiction:

Improvebrownin and brownout detectionVSAvoidpin count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The COMP pin is configured to serve multiple functions: during normal operation it acts as the output node of the error amplifier for voltage regulation, and during startup or fault conditions it can detect brownin and brownout conditions through the detection circuit. This multi-functionality eliminates the need for separate dedicated detection pins while maintaining all required functionalities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the brownin/brownout detection function with the existing COMP pin and error amplifier circuitry. The detection circuit is integrated into the same pin structure, combining what would traditionally be separate functions into a unified design that reduces pin count.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If an extra pin is added for brownin and brownout detection, then detection functionality is improved, but manufacturing cost increases

Engineering Contradiction:

Improvebrownin and brownout detectionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The COMP pin is configured to serve multiple functions: during normal operation it acts as the output node of the error amplifier for voltage regulation, and during startup or fault conditions it can detect brownin and brownout conditions through the detection circuit. This multi-functionality eliminates the need for separate dedicated detection pins while maintaining all required functionalities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the brownin/brownout detection function with the existing COMP pin and error amplifier circuitry. The detection circuit is integrated into the same pin structure, combining what would traditionally be separate functions into a unified design that reduces pin count.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9112418B2Controller for a switched mode power supply having an integrated circuit with multifunction pin

Publication Date: 2015.08.18 NANJING GREENCHIP SEMICON CO LTD

AI summary

Disclosure includes a controller in an integrated circuit and a related switched mode power supply. The switched mode power supply has an input power line and a ground line. An inductive device and a power switch are connected in series between the input power line and the ground line. The controller has a multifunction pin and is configured for controlling the power switch. A resistor connects the multifunction pin to the input power line. During a startup procedure, the controller provides a first conduction path conducting from the multifunction pin to the ground line. During normal operation, the controller disconnects the first conduction path, and makes the multifunction pin an output node of an error amplifier comparing a regulated output with a target value, to generate a PWM signal for controlling the power switch.