Low consumption voltage boost device

Claim 2

A voltage boost device comprising: a supply line supplying a supply voltage; an input terminal receiving an operating condition signal having a first logic level, representing a standby operation state, and a second logic level, representing an active operation state; an output terminal supplying an output voltage higher than said supply voltage; a first voltage boost stage connected to said supply line; a second voltage boost stage connected to said supply line; and a switch circuit connected between the first and second voltage boost stages and said output terminal, the switch circuit coupled to receive the first and second logic levels to selectively connect the first voltage boost stage to the output terminal, or alternatively, the second voltage boost stage to the output terminal; said first voltage boost stage being enabled in the presence of said second logic level of said operating condition signal and being disabled in the presence of said first logic level of said operating condition signal, and said second voltage boost stage being controlled in a first operating condition in the presence of said first logic level of said operating condition signal, and being controlled in a second operating condition in the presence of said second logic level of said operating condition signal.

Claim 3

The voltage boost device according to claim 1 , wherein the switch circuit includes a first switch that is coupled between said first voltage boost stage and said output terminal, and a second switch that is coupled between said second voltage boost stage and said output terminal, said first switch being closed in the presence of said second logic level and being open in the presence of said first logic level of said operating condition signal, and said second switch being open in the presence of said second logic level and being closed in the presence of said first logic level of said operating condition signal.

Claim 4

The voltage boost device according to claim 2 , wherein said second voltage boost stage comprises: a charge pump device having a control input and a high voltage output which is connected to said output terminal via said second switch means and generates a boosted voltage; self-activation means having an input connected to said output terminal, an activation input receiving said operating condition signal, and a phase output connected to said control input of said charge pump circuit; said self-activation means generating a standby timing signal supplied on said phase output when said output voltage is lower than a first preset threshold value and in presence of said first logic level of said operating condition signal.

Claim 5

The voltage boost device according to claim 3 , wherein said self-activation means comprises: a divider set between said output terminal and a reference potential line and having an intermediate node at an intermediate voltage: comparator means having a first input connected to said intermediate node, a second input receiving a constant reference voltage, and an output supplying a control signal; and phase generating means controlled by said control signal and generating said standby timing signal.

Claim 6

The voltage boost device according to claim 4 , wherein said second switch means comprises high voltage switches, and wherein a voltage boost circuit having a supply input connected to said high voltage output of said charge pump circuit and an output generating a closing signal for said high voltage switches when the value of said output voltage is lower than said first preset threshold value.

Claim 7

The voltage boost device according to claim 5 , wherein said voltage boost circuit comprises an enabling input receiving said operating condition signal and controlling opening of said switch means in presence of said first level of said operating condition signal.

Claim 8

The voltage boost device according to claim 4 , wherein said phase generating means comprises: an oscillator circuit generating said standby timing signal; a selector stage having a first input connected to said oscillator circuit, a second input receiving an active operation timing signal, a third input receiving a selection signal having a first and a second logic levels, and an output selectively supplying said standby timing signal and said active operation timing signal according to said logic levels of said selection signal, said selection signal having said first logic level in presence of said second level of said operating condition signal and having said second logic level in presence of said first level of said operating condition signal, when said boosted voltage is lower than a second preset threshold value.

Claim 9

The voltage boost device according to claim 4 , wherein said divider has a variable dividing ratio.

Claim 10

The voltage boost device according to claim 8 , wherein said divider comprises a first resistive element including a first transistor having its gate and drain terminals connected to said reference potential line, and its source terminal connected to said intermediate node; and a second resistive element comprising a plurality of second transistors and a plurality of selectable branches.

Claim 11

The voltage boost device according to claim 9 , wherein each of said selectable branches comprises a respective selectable transistor having its gate and drain terminals connected to a node, and its source terminal connected to said output terminal through a respective selection switch.

Claim 12

The voltage boost device according to claim 10 , wherein said selectable transistors have respective form factors that are different from one another.

Claim 13

The voltage boost device according to claim 9 , wherein said second transistors have respective form factors that are identical to that of said first transistor.

Claim 16

Method according to claim 13 , wherein an output voltage of said secondary voltage boost device exceeds said selected value.

Claim 17

Method according to claim 13 , wherein an output terminal of said secondary voltage boost device is connected to said input terminal of said load device.

Claim 18

A voltage boost device comprising: a load device having an input terminal coupled to receive a boosted voltage; a primary voltage boost stage that is enabled while said load device is in an active operating mode, said primary boost stage providing sufficient power for active operation of said load device; a secondary voltage boost stage that is enabled while said load device is in a standby mode, said secondary voltage boost device providing sufficient power to maintain a desired voltage level at said input terminal while said load device is in a standby mode; and a switching circuit coupled between the primary voltage boost stage and the secondary voltage boost stage, to couple the primary voltage boost stage to the input of the load device while in the active operating mode, or alternatively, to couple the secondary voltage boost stage to the input of the load device while in the standby mode.

Claim 19

A voltage boost device comprising: a load device having an input terminal coupled to receive a boosted voltage; a primary voltage boost stage that is enabled while said load device is in an active operating mode, said primary boost stage providing sufficient power for active operation of said load device; a secondary voltage boost stage that is enabled while said load device is in a standby mode, said secondary voltage boost device providing sufficient power to maintain a desired voltage level at said input terminal while said load device is in a standby mode; and a switching circuit coupled between the primary voltage boost stage and the secondary voltage boost stage, to couple the primary voltage boost stage to the input of the load device while in the active operating mode, or alternatively, to couple the secondary voltage boost stage to the input of the load device while in the standby mode.

Claim 20

Voltage boost device according to claim 16 , wherein said primary voltage boost stage is disabled while said memory device is in standby mode.

Claim 21

Voltage boost device according to claim 16 , wherein said load device is a memory device.

Claim 22

Voltage boost device according to claim 16 , wherein said secondary boost device is enabled while said load device is in active operating mode.

Claim 23

Voltage boost device according to claim 19 , wherein operation of said secondary voltage boost device comprises: intermittent active operation as required to maintain voltage at said input terminal at said desired voltage level while said primary boost stage is disabled; intermittent active operation as required to maintain voltage at said input terminal at said desired voltage level while said primary boost stage transitions from disabled to enabled; intermittent active operation as required to maintain an internal charge at said desired value during active operation of said load device.

Claim 24

A voltage boost device comprising: a supply line supplying a supply voltage; an input terminal receiving an operating condition signal having a first logic level, representing a standby operation state, and a second logic level, representing an active operation state; an output terminal supplying an output voltage higher than said supply voltage; and a first voltage boost stage connected to said supply line, a second voltage boost stage connected to said supply line; and said first voltage boost stage being enabled in the presence of said second logic level of said operating condition signal and being disabled in the presence of said first logic level of said operating condition signal, and said second voltage boost stage being controlled in a first operating condition in the presence of said first logic level of said operating condition signal, and being controlled in a second operating condition in the presence of said second logic level of said operating condition signal, wherein a first switch is coupled between said first voltage boost stage and said output terminal, and a second switch is coupled between said second voltage boost stage and said output terminal, said first switch being closed in the presence of said second logic level and being open in the presence of said first logic level of said operating condition signal, and said second switch being open in the presence of said second logic level and being closed in the presence of said first logic level of said operating condition signal.

Claim 25

A voltage boost device comprising: a supply line supplying a supply voltage; an input terminal receiving an operating condition signal having a first logic level, representing a standby operation state, and a second logic level, representing an active operation state; an output terminal supplying an output voltage higher than said supply voltage; and a first voltage boost stage connected to said supply line, a second voltage boost stage connected to said supply line; and said first voltage boost stage being enabled in the presence of said second logic level of said operating condition signal and being disabled in the presence of said first logic level of said operating condition signal, and said second voltage boost stage being controlled in a first operating condition in the presence of said first logic level of said operating condition signal, and being controlled in a second operating condition in the presence of said second logic level of said operating condition signal, wherein a first switch is coupled between said first voltage boost stage and said output terminal, and a second switch is coupled between said second voltage boost stage and said output terminal, said first switch being closed in the presence of said second logic level and being open in the presence of said first logic level of said operating condition signal, and said second switch being open in the presence of said second logic level and being closed in the presence of said first logic level of said operating condition signal.

Claim 26

The voltage boost device according to claim 21 wherein said second voltage boost stage comprises: a charge pump circuit having a control input and a high voltage output which is connected to said output terminal via said second switch and generates a boosted voltage; self-activation circuit having an input connected to said output terminal, an activation input receiving said operating condition signal, and a phase output coupled to said control input of said charge pump circuit; said self-activation circuit generating a standby timing signal supplied on said phase output when said output voltage is lower than a first preset threshold value and in the presence of said first logic level of said operating condition signal.

Claim 27

The voltage boost device according to claim 22 wherein the said self-activation circuit comprises: a divider set between said output terminal and a reference potential line, and said divider having an intermediate node at an intermediate voltage: comparator circuit having a first input connected to said intermediate node, a second input receiving a constant reference voltage, and an output supplying a control signal; and phase generating circuit controlled by said control signal and generating said standby timing signal.

Claim 28

The voltage boost device according to claim 23 , wherein said second switch comprises high voltage switches, and wherein a voltage boost circuit having a supply input connected to said high voltage output of said charge pump circuit and an output generating a closing signal for said high voltage switches when the value of said output voltage is lower than said first preset threshold value.

Claim 29

The voltage boost device according to claim 24 , wherein said voltage boost circuit comprises an enabling input receiving said operating condition signal and controlling opening of said switch circuit in the presence of said first level of said operating condition signal.