PWM Latch Mode Control Circuit Using Discharge Current

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Solution Overview

Problem

Existing pulse width modulation circuits face challenges with latch mode protection, including increased chip area due to stabilizing diodes, vulnerability to external environmental temperature, and ±5% voltage level errors.

Innovation Solution

A circuit comprising a D flip-flop, voltage generation unit, and comparator that generates a switch control signal to equalize discharge and charge currents, allowing precise control of a predetermined pin voltage and calculation of time for voltage decrease using a capacitor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a stabilizing diode is used to set the voltage level after latch mode protection is removed, then the voltage level can be controlled, but the chip area increases

Engineering Contradiction:

Improvevoltage level controlVSAvoidchip area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent extracts and removes the stabilizing diode from the circuit, replacing it with a voltage generation unit that uses a discharge current to achieve the same voltage level control function without occupying additional chip area

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the physical stabilizing diode component with an electrical current-based voltage generation mechanism, substituting a hardware component with a controllable electrical process that achieves the same functional outcome

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a stabilizing diode is used to set the voltage level, then voltage control is achieved, but the voltage level is easily influenced by external environmental temperature

Engineering Contradiction:

Improvevoltage level stabilityVSAvoidtemperature influence

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the temperature-sensitive stabilizing diode with a voltage generation unit that produces a discharge current, substituting a component affected by thermal environment with a controllable electrical current source that is not easily influenced by external temperature

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from using a passive diode's fixed voltage drop characteristic to an active current generation approach where the discharge current can be controlled to maintain stable voltage levels regardless of temperature variations

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a stabilizing diode is used to set the voltage level, then voltage control is provided, but a ±5% error is introduced

Engineering Contradiction:

Improvevoltage level accuracyVSAvoidvoltage level error

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent removes the stabilizing diode that introduces manufacturing tolerance errors, replacing it with a voltage generation unit that produces a discharge current with better precision and controllability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the imprecise diode voltage drop mechanism with a controllable current-based voltage generation system that eliminates the ±5% manufacturing error inherent in diode components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 provides accurate, environment-independent unlatched voltage control, reducing chip area requirements and eliminating voltage level errors, enabling users to adjust and time the voltage decrease accurately.

Implementation Method 1

the voltage divider resistor group generates a first voltage according to the discharge current and a charge current generated by a primary side of an alternating current/direct current converter

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

The comparator is used for comparing a reference voltage with the first voltage to generate a comparison signal

Methodology Applied

Scientific EffectElectrical potential difference comparison:

Data Source

PatentUS9197054B2Circuit for controlling a latch mode of a pulse width modulation circuit and method thereof

Publication Date: 2015.11.24 LEADTREND TECH

AI summary

A circuit for controlling a latch mode of a pulse width modulation circuit includes a D flip-flop, a voltage generation unit, a comparator, and a logic unit. The D flip-flop generates a switch control signal according to a latch enable signal. The voltage generation unit generates a discharge current, and a voltage divider resistor group included in the voltage generation unit generates a first voltage when the voltage generation unit is turned on according to the switch control signal. A voltage of a predetermined pin of the pulse width modulation circuit is equal to a predetermined voltage when the discharge current is equal to the charge current. The comparator compares a reference voltage with the first voltage to generate a comparison signal. The logic unit generates a clear signal according to the comparison signal. The D flip-flop clears the switch control signal according to the clear signal.