Two-Stage Level Shifter for Power-Sequence Fault Protection

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Solution Overview

Problem

Existing level shifters in multi power supply systems face issues with inconsistent output voltage levels due to incorrect power-on sequences, leading to potential physical damage from short-circuit currents when MOS transistors are improperly activated.

Innovation Solution

A multi power supply type level shifter with a detecting unit that ensures constant output voltage levels by monitoring and adjusting node voltages based on the application sequence of power supplies, preventing short-circuit currents by maintaining nodes at predetermined levels even when the power-on sequence is altered.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If power supply voltages are applied in a predetermined sequence (VDDL->VSSH->VDDH), then the level shifter operates reliably with constant output voltage levels, but the system becomes vulnerable to short-circuit currents and physical damage when the sequence is altered due to faults or external noise

Engineering Contradiction:

Improveoperation reliabilityVSAvoidshort-circuit current damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The detecting unit proactively monitors the power-on sequence before the level shifter operates, detecting whether VDDL, VSSH, and VDDH are applied in the correct order. When an incorrect sequence is detected, the system preemptively adjusts the operation of MOS transistors to prevent short-circuit currents, rather than waiting for damage to occur

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The detecting unit continuously monitors the power supply sequence and provides feedback to control the level shifter's operation. When the monitoring unit detects an incorrect power-on sequence, it signals the level shifter to adjust its transistor operation accordingly, creating a closed-loop control system that adapts to power supply conditions

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If the level shifter uses multiple power supplies (VDDL, VDDH, VSSH) to handle different voltage levels, then it can interface between circuit blocks with different voltages, but it becomes susceptible to improper MOS transistor activation when power sequences are incorrect

Engineering Contradiction:

Improvevoltage level adaptationVSAvoidcircuit device safety

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The detecting unit acts as an intermediary between the power supply system and the level shifter. It monitors the power-on sequence and mediates the operation of MOS transistors based on the detected sequence, preventing improper activation that would occur with multiple power supplies under incorrect sequencing conditions

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9024675B2Multi power supply type level shifter

Publication Date: 2015.05.05 MAGNACHIP SEMICON LTD

AI summary

There is provided a multi power supply type level shifter. The provided multi power supply type level shifter includes a first level shifter and a second level shifter in a two-stage architecture so as to selectively receive first to third power supplies and change a signal level, even when the first to third power supplies are applied in a different sequence from a normal power-on sequence. Output voltages are output without a change in level, and short-circuit currents are not generated in the first and second level shifters.