Power-Down Detection Circuit With Temperature-Stable Trimmed Threshold
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Solution Overview
Problem
Existing power down detection circuits in semiconductor storage devices, such as NAND flash memory, face instability due to temperature dependence when adjusting the power down detection level, leading to incorrect detection of supply voltage drops, causing repeated resets or missed detections.
Innovation Solution
A power down detection circuit that generates a temperature-compensated reference voltage, adjusts it to produce a lower reference voltage for power down detection, and uses a comparator to detect when the internal voltage falls below this adjusted level, thereby suppressing temperature dependence and stabilizing the detection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power down detection level is adjusted in existing circuits, then the detection threshold can be changed, but temperature dependence causes detection instability and incorrect readings
Solution Approach 1:
The patent changes the temperature parameter by introducing a temperature compensation circuit that generates a compensation voltage varying with temperature. This compensation voltage is added to the reference voltage to offset temperature-induced drift in the detection threshold, allowing the circuit to maintain stable detection levels across different temperatures while preserving adjustability through the trimming circuit.
Solution Approach 2:
The patent introduces a temperature compensation circuit as an intermediary element between the reference voltage source and the comparator. This intermediary generates a temperature-dependent compensation voltage that mediates the temperature effects, allowing the detection circuit to remain stable across temperature variations while maintaining its adjustment capability through the trimming circuit.
2Use of energy by moving object
If a simple comparator circuit is used for power down detection, then current consumption in standby mode is reduced, but temperature dependence reduces measurement precision
Solution Approach 1:
The patent modifies the reference voltage parameter by adding a temperature compensation component. The compensation voltage changes with temperature to counteract drift in the detection threshold, thereby maintaining measurement precision without requiring additional active circuits that would increase standby current consumption.
Solution Approach 2:
The temperature compensation circuit acts as an intermediary that subtly adjusts the reference voltage based on temperature conditions. This intermediary function improves measurement precision by offsetting temperature effects while keeping the overall circuit structure simple and power consumption low in standby mode.
3Device complexity
If the reference voltage is directly used for power down detection, then the circuit structure remains simple, but temperature variations cause detection level drift
Solution Approach 1:
The patent changes the reference voltage parameter by superimposing a temperature compensation voltage on it. This modification allows the detection level to remain consistent across temperature variations while adding only a moderate amount of circuit complexity through the temperature compensation network and trimming circuit.
Solution Approach 2:
The temperature compensation circuit serves as an intermediary between the simple reference voltage source and the detection comparator. It introduces minimal complexity by generating a small compensation voltage that stabilizes the detection level against temperature drift, thereby improving stability without significantly increasing device complexity.
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 effectively adjusts the power down detection level while minimizing temperature dependence, ensuring accurate detection of supply voltage drops and preventing both false resets and missed detections, thus enhancing the operational stability of the semiconductor storage device.
Implementation Method 1
a band gap reference (BGR) circuit 30, which generates a reference voltage VREFI based on the supply voltage VCC
Implementation Method 2
a comparator 60, which compares the reference voltage VREFI with the internal voltage VCC_DIV, and outputs the reset signal PDDRST
Data Source
AI summary
A power down detection circuit and a semiconductor storage apparatus, which can adjust a power down detection level while suppressing temperature dependence, are provided. The power down detection circuit includes a BGR circuit, a trimming circuit, a resistance division circuit, and a comparator. The BGR circuit generates a reference voltage based on a supply voltage. The trimming circuit adjusts the reference voltage based on a trimming signal to generate a reference voltage for power down detection. The resistance division circuit generates an internal voltage lower than the supply voltage. The comparator detects that the internal voltage is lower than the reference voltage for power down detection and outputs a reset signal.