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Circuit and Method of Providing A Permanent Pull-Down for Reducing Power Consumption

IP.com Disclosure Number: IPCOM000011801D
Publication Date: 2003-Mar-17
Document File: 7 page(s) / 272K

Publishing Venue

The IP.com Prior Art Database

Abstract

A problem for many circuits has been the difficulty in which to provide continued functionality after a polarization current has been removed. Traditional pull down structures do not recover without other intervention (such as manual reset). This is both costly and undesirable as customers demand hands off operation. Furthermore, it has been difficult to draw an input pin down to low level (Ground voltage) when the latter is left floating (open circuit) to ensure power consumption is eliminating. Additionally, any node connected to an impedance sinking current must meet industry standard electro-static discharge (ESD) requirements, and yet avoid inducing oscillation when switching. In order to draw charges to a ground voltage, a high impedance is desirable, at least until a low voltage level is reached. High impedance is an important factor in reducing power consumption when an input voltage level is continuously varied. Prior art forces this voltage to high voltage level for a period of time, enabling the system to continue operation. It is also desirable to have this sinking impedance occur during an operating mode for a period required, and it must keep on drawing the input node to a lowest voltage level even in when in a shutdown configuration. While prior art includes a pull-down resistor, this solution requires an unacceptable utilization of die space. Furthermore, other means such as using polysilicon or a well layer to make the resistance introduces large errors induced from temperature, voltage and process variations. Alternatively, use of transistors with input pins connected to high voltage when an input pin is disconnected from the power supply (or even worse, left open) results in the corresponding impedance cancelled or unknown. Thus for at least the reasons above, it is desirable to provide a new method and circuit for Providing a permanent pull-down for reducing power consumption during stand-by.

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Circuit and Method of Providing A Permanent Pull-Down for Reducing Power Consumption

Background

A problem for many circuits has been the difficulty in which to provide continued functionality after a polarization current has been removed.� Traditional pull down structures do not recover without other intervention (such as manual reset).� This is both costly and undesirable as customers demand hands off operation.� � � Furthermore, it has been difficult to draw an input pin down to low level (Ground voltage) when the latter is left floating (open circuit) to ensure power consumption is eliminating. � Additionally, any node connected to an impedance sinking current must meet industry standard electro-static discharge (ESD) requirements, and yet avoid inducing oscillation when switching.� In order to draw charges to a ground voltage, a high impedance is desirable, at least until a low voltage level is reached. � High impedance is an important factor in reducing power consumption when an input voltage level is continuously varied. � Prior art forces this voltage to high voltage level for a period of time, enabling the system to continue operation. � It is also desirable to have this sinking impedance occur during an operating mode for a period required, and it must keep on drawing the input node to a lowest voltage level even in when in a shutdown configuration.

While prior art includes a pull-down resistor, this solution requires an unacceptable utilization of die space. Furthermore, other means such as using polysilicon or a well layer to make the resistance introduces large errors induced from temperature, voltage and process variations. � Alternatively, use of transistors with input pins connected to high voltage when an input pin is disconnected from the power supply (or even worse, left open) results in the corresponding impedance cancelled or unknown. �

� Thus for at least the reasons above, it is desirable to provide a new method and circuit for Providing a permanent pull-down for reducing power consumption during stand-by.

FIG.1

Detailed Description

One solution to the aforementioned problems includes the use of a novel method and circuit for reduced polarization current.� This enables obtaining a high impedance (for example, 10 Mega Ohms) without requiring a large transistor length. Referring to the schematic, this current is generated from M19 current source. The cu...