Mid-Range LDO Regulator for SOA Protection in Power-Down

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Solution Overview

Problem

Semiconductor devices require different voltage levels for core and input/output devices, and maintaining a Safe Operating Area (SOA) is challenging, especially during power-down modes without external reference inputs.

Innovation Solution

A middle-range LDO voltage regulator with sinking and sourcing capability, comprising an amplifier, VREFGEN, PDCTRL, and decoupling capacitor, dynamically tracks IO and core power, maintaining a stable voltage reference and high ground signal to ensure SOA across active and power-down modes, with high decoupling capacitor density for area efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional voltage regulator is used, then voltage levels can be shifted for different devices, but the Safe Operating Area (SOA) cannot be maintained during power-down modes without external reference inputs

Engineering Contradiction:

ImproveSafe Operating Area maintenanceVSAvoidPower-down mode operation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The LDO voltage regulator uses an internal voltage reference generator that autonomously maintains a stable reference voltage without requiring external reference inputs during power-down modes. The regulator serves itself by generating the necessary reference voltage internally, ensuring continuous SOA protection across all operating modes including power-down.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The LDO dynamically adapts its operation between active and power-down modes while maintaining SOA protection. The regulator adjusts its internal circuitry operation based on the operating mode, enabling versatile power management while preserving the critical function of voltage reference stability and SOA maintenance throughout the transition.

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If decoupling capacitor area is increased, then voltage stability improves, but layout area increases

Engineering Contradiction:

ImproveVoltage stabilityVSAvoidDecoupling capacitor area

Core Design Contradiction:

Stability of the object's compositionVSArea of stationary object

Solution Approach 1:

The LDO employs high-density decoupling capacitor structures that achieve superior voltage stability with reduced physical area. By optimizing the capacitor density parameter and using advanced capacitor design techniques, the regulator attains enhanced voltage stability without proportionally increasing the layout area, thus resolving the trade-off between stability and area.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250244784A1Low-dropout (LDO) voltage regulator

Publication Date: 2025.07.31 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A middle-range (mid) low dropout (LDO) voltage has both sinking and sourcing current capability. The mid LDO can provide a voltage reference in active mode and power mode for core only design to work in a Safe Operating Area (SOA). The output of mid LDO can track IO power and/or core power dynamically. The mid LDO can comprise a voltage reference generator and a power-down controller connected to an amplifier, which output is connected to a decoupling capacitor. The provision of a high ground signal allows the mid LDO provide the sinking and sourcing currents.